For contact info, please see the Sci.Electronics.Repair FAQ Email Links Page.
Copyright © 1994-2022
Reproduction of this document in whole or in part is permitted if both of the
following conditions are satisfied:
1. This notice is included in its entirety at the beginning.
All Rights Reserved
2. There is no charge except to cover the costs of copying.
Although working on cameras is generally
less risky than dealing with microwave ovens, TVs, and computer
monitors, there is one component in every camera with an electronic
flash - even the least
expensive throw-away variety - that is potentially lethal. Specifically,
it is the energy storage capacito.
And of course even more so for separate electronic flash units
or "speed lights" with their higher energy.
This may charge up as soon as power is turned regardless
of whether flash is called for, and may retain a dangerous charge for hours or
days. If working inside a camera or flash unit, on one that has
had its case damaged exposing internal parts, it is essential that you
read, understand, and
follow all safety guidelines contained in this document and in the document:
Safety Guidelines for High Voltage and/or Line Powered
Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied:
1. This notice is included in its entirety at the beginning.
If there is no electronic flash, the greatest risk is torn flesh from sharp sheet metal or gear teeth. ;-)
We will not be responsible for damage to equipment, your ego, county wide power outages, spontaneously generated mini (or larger) black holes, planetary disruptions, or personal injury or worse that may result from the use of this material.
For the specific case of the (mostly older) flat head screws, fabricating a driver with an aluminum blade is recommended to prevent damage to the screw slots. These screws also tend to have long thin slots, which don't fit the typical screwdriver well at all. The special tool can be as simple as an aluminum roofing nail with its point filed down to a thin blade. Damage to the screw slots is almost unavoidable with a steel screwdriver, and at the very least, looks bad. ;( The softer blade will get chewed up after a while but that can be repaired.
Most in modern Nikon cameras and lenses are self-tapping plastic screws with a coarse thread. For the few metal parts, they are fine-thread machine screws. There are several sizes used and they are not interchangeable! So it's best to keep track of the specific screws at each step by storing them in plastic baggies. Pill organizers are also useful but an accidental whack can send the screws all over the place. ;-(
NEVER use excessive torque in tightening screws! It doesn't take much to strip threads in soft plastic, especially for the tiniest screws. And take care not to start the screw at an angle and cross-thread the hole. There will be definite resistance but should never be an indication of bottoming. That probably means the wrong screw length was used. If it seems more difficult to install than to remove, it's probably the wrong screw.
A very few screws in cameras have a left-hand thread. I've seen exactly one (1) case of this - in the Copal Square S shutter (used in the Nikkormat FT/FTN among others) - which secures the "Slow Speed Lever" or "Retard Drive Cam" depending on which manual is being referenced. But be on the lookout - if the screw seems to get tighter, try the other way. ;-) Being overzealous and breaking or stripping the screw shaft would likely be fatal to the camera both because finding a replacement screw would be impossible and the remains of the screw is solidly stuck in the hole. ;-(
Mirrorless cameras are essentially the professional versions of point-and-shoots with a high resolution LCD viewfinder instead of an optical viewfinder (in addition to the normal LCD display) both fed from the main sensor. And a price tag 10x to 100x higher. ;-)
Note: One would think that when shooting with a DSLR in "live view" mode (which uses the sensor with the mirror up) it would behave like a point-and-shoot and be silent if the simulated shutter sound is turned off. But this is usually not the case for technical reasons having to do with the way the sensor reads out data: The mirror flips down and the mechanical shutter closes, then it opens for the exposure and closes after the exposure, and then the mirror flips up, and the shutter opens. That's why the entire sequence of events when pushing the shutter button takes a lot longer and is noisier with live view. Try it! ;-(
In the end, the quality of your photos will depend more on care in composition, lighting, a steady hand, and other factors not part of the camera itself. Technology can help but it doesn't replace these. No matter the cost of the equipment, if the lighting is not balanced or the depth of field is too shallow, the photos will be poor.
40+ years ago I owned top-of-the-line Nikon film SLRs including the flagship Nikon Photomic FTN body with several Nikon fixed focal length lenses. Zoom lenses were a pricey extravagance back then. The FTN body alone was around $350 in 1970s dollars, which would be comparable to roughly $2,000 now accounting for inflation. In those days the only assistance was the built-in exposure meter. Focus and aperture were manual. I did my own darkroom work and ended up with a few good pictures and a lot of mediocre ones. Nowadays I have several low-mid level Nikon DSLRs purchased for either $500 new (D5600) or much much less than that on eBay (D70, D80, D3000, D5200, etc.) and several lenses, but what I had been using most before the development (no pun) of this document was a Canon SX710HS point-and-shoot, primarily for Website photos. It was around $100 on eBay several years ago. A Nikon D70 (one of two each for $10 on eBay excluding lens but including shipping) has been used for most of the DSLR and lens dissection photos later in this document, but it's not clear if the resulting photos are really any better on average than using the Canon.
So start out with your phone. If that proves to be too limiting, try an inexpensive point-and-shoot and explore its more advanced capabilities. After that, consider a low-end or older DSLR. One doesn't need to spend many hundreds or thousands of dollars to get started. As noted, most of the photos linked from this page were taken with a Nikon D70 picked up on eBay for $10, with various zoom lenses, typically around $25. Add a battery, charger, and neck strap, and the entire outfit was less than $50. Getting deals like that take some effort, patience, and luck. ;-) But a camera with a "standard" or "kit" autofocus zoom lens and other required accessories that provides many features of more expensive ones can be had for $150 or less on eBay. Use that for a while and see if its benefits outweigh the hassle of lugging around several pounds of photo gear. And like boating, serious photography can end up becoming a money pit. ;-( ;-)
Later on, semi-antique ;-) 75 watt genuine incandescent lamps were substituted for the LED bulbs with the camera's "White Balance" set to incandescent and no flash. This appears to have better color redition requiring less fiddling with corrections. The D70 was usually set to Manual at f/18 except for some extreme closeups where even greater depth of field was desired.
Sometimes there will be subtle blueish highlights in the photos. While that adds character, what it really means is I forgot to turn off the ceiling daylight or cool white T40 fluorescent replacement LED lamp when shooting. ;-)
A very few shots were taken with a Canon SX710HS, usually where the bulk of the D70 was a hindrance. They were mostly hand-held with flash. See if you tell which. ;-)
inPixio produces PNGs with transparency for the (removed) background by default which then appears black and there doesn't appear to be a way to change that in the on-line free version, so XnConvert Batch Converter was used to generate JPGs with a white background. The filename option should be blank so as not to add extraneous junk to it. For one at a time, MSPaint or something similar can do the conversion. But some will preserve the transparency which may be undesirable.
There is a D70 repair manual on-line. Search for "Nikon D70 Repair Manual PDF". It has many detailed photos with step-by-step disassembly and reassembly, some explanations, and parts identification.
I've actually come to like this camera despite having owned top-of-the-line Nikon F film SLRs many years ago as well as the newer D5600 and other D5xxx DSLRs. While the D70 is heavy and clunky (politely perhaps referred to as more "Solid") compared to newer Nikon DSLRs and has limitations, it is relatively simple to use with no excessive creeping featurism, excellent battery life since nothing is really running until the shutter button is pressed as there is no power hog live view mode, has a fast shutter response, and, uh, also takes decent pictures. ;-) This one has a shutter count of around 12K, so it's really only a teen as these things go. ;-) See my general comments on a "Selecting a Type of Digital Camera". You may be surprised at my conclusions.
The photos may be viewed at: Nikon D70 DSLR Dissection Web Album. (This opens in a single new tab or window depending on how your Browser is set up.) Some of the photos may be rather gory. So send the kids and pets to another room. ;-) These shots start with an intact camera similar to the one being discombobulated, and then the core, various covers (including the back one with the LCD), the microcontroller PCB - essentially almost everything that can be detached with only the use of a screwdriver and by unplugging cables. Reassembly would be straightforward, at least in principle with adequate notes, closeup photos, and some luck. Beyond this point, except for removing the CCD assembly, wires have to be unsoldered or cut. As can be seen, this has now commenced as the necessary chants and incantations to the gods of dead cameras have been issued and notarized. ;-) And yes, a close examination of the photos will reveal that a pair of buttons did disappear before they should have during the disassembly and I didn't notice. Live with it. ;-)
And as noted in the introduction, to complete the circle, the photos were taken with another D70. ;-)
Here are the descriptions:
First, the battery was removed since various pins on the connectors will be live even if the camera is OFF. The high voltage on the electronic flash components should not be anywhere near this area of the camera so that should not be a concern. The PCB on the bottom of the D70 has the main microprocessor, non-volatile memory, and RAM. The firmware is probably stored in the 29LV160TE 16M bit flash memory IC next to the chip with the Nikon label. So in principle, it could be swapped, but that's above my pay grade. ;-) Replacing the PCB is only a matter of screws and connectors. And the donor PCB had already been removed from its host during the dissection. Of course, nothing is ever quite so simple as there are at least a half dozen screws of several different lengths and their heads look identical, so either (1) care must be taken to arrange the screws in the correct relative positions after each is removed or (2) they can be compared to the unmodified D70. All the screws around the perimeter of the bottom cover must be removed along with the one on the bottom of the front lens housing, but not the inner ones that secure the metal base/shield inside the cover. Then cover can be angled up and slid off of the USB connector on the PCB.
There are 5 ribbon cables that need to be unplugged. For all except the large one at the end next to the Nikon chip, the black fasteners flip up; for the remaining one it slides out. If a wrong move is attempted something may break and it may not possible to assure the cables make good contact with the connector pins. Once the fasteners are released, the cables will slide out. The 4 large-head silver screws securing the PCB can be removed and the PCB will unplug from a white connector underneath and slide out of the USB housing.
Reassemble in reverse order. There are one or two cushy gray conductive pieces that technically should be replaced but they popped out when the PCB was removed and I could not determine where they went. So be it. ;( ;-) Taking the bottom plate off the other working D70 to check is not going to happen.
After reassembly, it was possible to upgrade the firmware so the 2 working D70 are now similar.
Then I was looking at the camera and realized that the reason the firmware would not upgrade was probably that it was actually a D70S, NOT a D70, though the V1.00 firmware may still have been out of date. There is no on-line way to upgrade the D70S firmware even though it appears as though the current revision may be something like V1.30. And some further digging revealed that the D70 V2.00 firmware is probably very close to the latest D70S firmware. So if that being totally confusing, it's staying the way it is until a reason appears to justify ripping the camera apart again. ;-) Since all functions I've tested seem to work with the D70 brain board (with V2.0 firmware) in the D70S camera, my conclusion is that there is no difference in the firmware.
The Franken-camera appears to work correctly and the photos look similar to the those from the other D70. However, what is not known includes whether there are actual physical differences between the D70 and D70s, and if there is a CCD defect map stored in a chip on the mainboard, which case it would not match. Nothing obvious has appeared but who knows? Most of the pics linked from here were taken with this camera so it appears to work well enough. ;-)
But a while later when attempting to set up a separate LCD monitor for viewing the photos after shooting, this camera does not recognize that a video cable is plugged in while an original D70 worked as described in the manual. It is not known whether this is a preexisting condition, damage caused by the transplant, or something else. Since the video plugs directly into the brain board, which is from a D70, it should behave like a D70. Lack of video is not a great loss though since the output from the camera is low resolution with mediocre quality and would be just barely useful anyhow - perhaps to confirm that the picture is framed correctly but not much else.
Don't panic as the previously recorded photos should still be present. But a suitable USB memory card reader may be required to recover them. Multi-format memory card readers are available for a few dollars on eBay and elsewhere if your PC doesn't have the capability built-in. Confirm that the model you select supports the memory card format! Many may not support the old CF format of the D70. Write capability is not necessary as it should be possible to format it in-camera, or in a Canon camera ;-) if that doesn't work. Formatting is recommended after the photos have been recovered to assure the card's file system is not corrupted.
There is a D80 repair manual on-line. Search for "Nikon D80 Repair Manual PDF". It has many detailed photos with step-by-step disassembly and reassembly, some explanations, and parts identification.
The $25 D80 selected for the tearup has problems with the gears driving the mirror and displays "Err" in the top LCD after valiant whirring attempts to reset it. This is repairable based on various Web videos, but requires an almost total teardown ;-) of the camera to be able to replace the motor assembly and/or large white gear. So while the tearup will reach that point, reassembly is probably not going to happen. ;-)
All photos were taken with the same D70 used for its portraits. ;-) I do have a working D80 but that may eventually be sold. Since its shutter count is over 66K, adding to that was not desirable. The shooting conditions are similar to those for the D70 with the same settings for Web Album Generator.
The photos so far may be viewed at: Nikon D80 DSLR Dissection Web Album. (This opens in a single new tab or window depending on how your Browser is set up.)
Here are the descriptions:
There may be more photos to come.
If what you want is entertainment with a bit of useful information, check out the YouTube video Prime Studios - Destroying a Nikon Camera or Web page with still shots PetaPixel - Step-by-Step Teardown of the Nikon D80 Shows You What's Inside a DSLR. Thankfully, both of these are the same D80 and it had already been fatally damaged before he got a hold of it, so the gore is tolerable. ;-)
For the specific problem this D80 has, namely the whirring gear error, there are a pair of more serious YouTube videos at Nikon D80 ERR Split Gear Part 1 which covers the disassembly to access the gear motor and Nikon D80 ERR Split Gear Part 2 which covers the installation of the replacement and then reassembly of the camera. And of course since there are a lot of shots of the camera in various stages of discombobulation nearly to the bare bones, it also serves as a decent dissection, though attempting to keep track of what screws were removed at each step may be rather challenging.
For this camera, the black gear attached to the motor shaft is indeed fractured so the motor spins with fully doing what it's supposed to do, but whether that happened on its own or was the result of excessive torque driving the mirror / shutter mechanism due to some other issue such as a faulty encoder position sensor is not known and I'm not really inclined to go to all the trouble of replacing the gear and reassembling the camera to find out. Sorry. ;-) Though the expense at least wouldn't be much as the gear in my dissected D70 is the same. Even if I didn't have that, there are over 100 listings on eBay for the gear, some under $3. It must be a common failure. And for someone with an attention to detail in keeping track of everything during disassembly (especially the locations of the solder joints for the dozen or so wires that need to be disconnected), repair should be straightforward if not cost effective. ;-)
And to top it off, I accidentally removed the motor mount (not just the motor and gearbox itself via the two large-head screws) and lost one of the rollers without even realizing it until the mirror would not come all the way down. Miraculously, I did find the roller later on the workbench and reinstalled it, but that's the reason why the mirror is in the fully up position in the Mirror Box photos rather than down as would have been preferred. ;( :-)
Coming soon. Photos of an intact D3000 may be viewed at: Nikon D3000 DSLR Dissection Web Album. (This opens in a single new tab or window depending on how your Browser is set up.) But that's so boring.
There is an internal flex cable running from near the center of the back panel assembly inside the rear cover of the camera to the LCD itself. It attaches to a "zero insertion force connector" - the ones with the thin lid that has to be flipped up to insert or remove the cable. In this case the cable is short and just barely reaches the connector. So even though additionally secured with a piece of tape, it apparently pulled out over time or more likely was never inserted quite correctly in the first place as that is a bit challenging. Voila, nothing on the LCD, only the back-light.
The rear cover of the camera is secured by 2 screws on either side, 2 screws near the viewfinder (partially hidden by the rubber eyepiece cup if present), 4 screws along the back edge of the bottom, 1 screw further in, and 1 screw under the rubber cover next to the battery compartment latch. There are several different size screws so make sure to set them aside labeled as to their origin. Once the screws have been removed, the rear cover can be popped off, perhaps with the aid of a thin blade. CAUTION: It is connected to the main board via another zero insertion force connector near the bottom so take care not to rip it.
With the rear cover separated from the body, the problem will be obvious. Remove what's left of the small piece of tape, flip up the latch, and carefully insert the cable so that it extends underneath the edge of the connector as far as it will go, and then flip the latch down. Then add a larger piece of Kapton or similar tape to help secure it. Or a bit of 5-Minute Epoxy. Camera operation can be carefully confirmed with the back in place but before installing the screws.
There are 4 sizes/types of screws and of course the same type of each needs to goback where it came from. ;-) These are: short, medium, long fine thread, and long coarse thread. But don't panic if the 2 types of long screws get mixed up, just try to get them back in their place. As with all camera and lens repairs, a high quality 00 or 000 Phillips screwdriver is a must. It may be possible to do the replacement without removing all the screws as specified below but it won't hurt. The bottom cover must be loosened at the very least to allow the back to be freed up to allow the SD door cover assembly to be removed.
It should now be possible to remove the bottom cover so the back cover can be lifted at the SD card-end freeing the SD card door assembly. The back cover does not need to be removed entirely, just 1/4 inch or so and in that case step 7 and possibly some others can be skipped), but if it is, take care not to tear the flex cable attaching it to the main PCB.
The SD card door assembly can now be pivoted up and removed.
Install the new one in reverse order. The screws should go back in easily, take care to avoid cross-threading any and do not over tighten - just snug.
There is a nice set of photos of the back removal process at iFixit Nikon D5200 Motherboard Or Camera Back Replacement.
The problem was immediately obvious: One half of the tiny black lever on flex cable connector going to the shutter button cluster was missing. This camera had obviously been opened by someone and they managed to snap it off. So, part of the connector was making somewhat reliable contact and the rest was making none at all. Pressing on the cable while simultaneously juggling the camera with three hands revealed that at least some of the missing functions had returned.
However, parts for these connectors aren't the sort of thing one can purchase at Radio Shack (even if Radio Shack still existed). I attempted to cannibalize one from a likely bad D5300 mainboard but either it wasn't the identical type or I messed up attempting to install it. which isn't surprising as these are barely visible even under manification. And it broke into 3 pieces when putting it back where it came from. Perhaps they are available on eBay for only $99+shipping. ;-)
Plan B was to fashion some sort of jig to apply the required pressure to the cable. The solution consists of a piece of resilient floor tile about 3/8 inches in length and 1/8 inch square, and a piece of stiff foam to press it against the connector using the back cover when it is in place. Can you say "Kludge"? ;-) But for the most part, it appears to have worked. Most of the missing functions have returned and appear to be reliable. There are still some funny things about the camera that may be related to why the original owner went inside. Or they could just be incorrect settings though everything was reset. One of these is that normal autofocus engaged by pressing the shutter release does not do anything, only by pressing AS/AF button can autofocus be initiated on demand. Continuous tracking AF does work. And the shutter button does work halfway because the flash pops up if needed. So a bit strange. More to come perhaps.
Notes on screw sizes and types:
The photos were taken with the second working D70 / D70s following its brain transplant. ;-)
The photos so far may be viewed at: Nikon D5300 DSLR Dissection Web Album. (This opens in a single new tab or window depending on how your Browser is set up.)
Here are the descriptions:
More to come, perhaps.
The following are more descriptive with only a few fairly simple repairs. On a scale of 0 to 10 modern lenses like this rank around -10 in ease of repair, at least for someone who hasn't dealt with them before. ;( Anything requiring more than the simplest disassembly is almost certain to make things worse and likely result in the thing turning into a high-tech paperweight - at least the first few times it's attempted. Where manual focus doesn't work on an autofocus lens, live with it. ;-) Even being able to lubricate the proper surfaces is likely to require extensive disassembly and the opportunity to tear a ribbon cable, break a connector, or lose itty-bitty screws or other almost invisible parts. For many Nikon lenses like this, there are (supposedly) original Nikon repair manuals on-line but don't expect there to be much in the way of real help. They make many assumptions, don't even go deep into some major assemblies, and suffer from poor English translation. In addition, depending on what was disturbed, some specialized test equipment and software may be required to tweak alignment. In fact it is hard to imagine that repair of a relatively low-end lens like these is ever really done by Nikon or an affiliate! And now with eBay, fully functional used specimens can be had for a fraction of the cost of the simplest professional repair.
Having said that, there are some repairs that can be tackled without a great deal of experience and a reasonble chance of success. These mostly relate to failures that can be dealt with by only disassembling the back and sometimes the front of the lens. But that covers a large percentage of common problems. And since the disassembly to that level tends to be very similar for most of these lenses, familiarity with one will be preparation for many others.
Level of difficulty: 2. Depending on the lens model, these parts may be available at reasonable cost since this is a common problem.
Level of difficulty: 1-2 depending on the specific lens. For some it is only a matter of unscrewing the lens group assembly.
Level of difficulty: 3. This is known to apply to lenses like the AF-S DX 18-55mm f/1:3.5-5.6G VR where the focus ring rotates and changes the focus directly. The required rollers also need to be available.
Level of difficulty: 3. Similar to above but some creativity in rebuilding some parts will be required.
Level of difficulty: 1. Most cable connectors are generally accessible after removal of the Bayonet Mount and Fixed Shell. However, some may be buried deep inside.
Level of difficulty: 3-5. In addition to access to the relevant PCB, some ability to test for basic component failures and skill in replacement of very small surface mount parts will likely be required. And identifying the part may prove challenging due to the SMT marking codes not being well documented.
Level of difficulty: 2 but see * note.
Level of difficulty: 0. Lenses that have been unused for a while but not in a sealed bag or container may experience buildup of a thin film of contamination on internal surfaces and contacts - specifically on the Focus and Zoom Encoder strips and switches. These lenses are not sealed at all. This may be particularly likely near or in a kitchen or machine shop but can happen almost anywhere. Working focus and zoom back and forth a dozen times may may be all that is required. If the lens will shoot at all, check the EXIF data on the resulting images to confirm at least that the zoom settings read back correctly. If this doesn't work, extensive disassembly may be required bumping the level of difficulty up significantly. Depending on the specific lens, one or both of these encoders may be buried deep inside, though sometimes access is provided by a window covered with a removable panel. For example, the AF-S DX 55-200mm f/1:4.0-5.6 VR lens has this for the Zoom Encoder (though not the Focus Encoder), accessible after the Rubber Grip is removed.
The same applies to Focus A/M or VR ON/OFF switches that don't have any effect. For many lenses, a single screw releases the switch plate providing access to test the switches and use some contact cleaner sparingly if needed. But take care not to rip the flex cable.
This is best done removed from the lens. It is generally possible to use something thin (but not sharp) to lift the front edge of the rubber grip and then go around and work it off the lens. Note that not all are symmetric so take note of front and back if that is the case. There is usually little or no adhesive securing it. Then it can be cleaned with soap and water and an old toothbrush. Dry thoroughly and replace. The only gotcha is that on some lenses, the rubber is so flabby that it won't return to its original shape and may be slightly loose. But sometimes it just takes time get back in shape. Otherwise, a bit or rubber cement may be used to secure it.
* On many lenses replacing some of the lens groups - including just putting the same ones back in place - in theory require optical alignment which is not possible without the proper Nikon test equipment and training. How well the lens would perform without alignment is not known. Even the thickness of any shims under the front lens group or Bayonet Mount are unique to each sample of the same model lens. The rear / back lens group is often mounted with oversize holes so it can be adjusted laterally before tightening the screws. If removing one of those, take a closeup photo first so it can be replaced as close as possible to its original position.
Some parts like the Bayonet Mount may be available at reasonable cost from Amazon, eBay, or even Nikon (gasp!), but anything else is likely to have to be cannibalized from a similar lens and the cost will be ridiculous if purchased by themselves. So what's the point other than for the challenge or excitement value. ;-) If you do decide to take the plunge on a more involved repair, shoot closeup photos at every step even if there is a repair manual available. The on-line repair manuals tend to be written in Japanish :( ;-) with many assumptions that are not documented. How the parts go back together may seem obvious as it's being taken apart, but may not be obvious an hour or day - or even a minute later. Label parts that fit together with "match marks" of some sort like coded scratches or white paint. Many assemblies may appear to have 3-fold symmetry, but that doesn't mean they will work correctly if the wrong choice made. In some cases it isn't quite 120 degrees; in others there are subtle differences preventing engagement of various parts. In short, adding match marks during disassembly is essential to retaining sanity when putting it all back together. Where a repair manual exists, it may references specific features but this is hit or miss. Segregate screws as well since not all the teeny-tiny screws are identical. Work on a surface where tiny parts won't go bouncing off to oblivion. There are unique screws for plastic and metal, and of different diameters and lengths. A padded surface may be useful as well as a magnetic pad to "store" screws and such. Or an egg carton or pill orgnaizer. Many of the threaded holes are into soft plastic so stripping them is always a risk. If a screw seems tight, it's probably the wrong diameter or length. A set of quality Jeweler's or miniature precision Philips screw drivers with magnetic or magnetizable tips is a must.
If a dozen of the identical model lenses need repair, then after the first 8 or so, this will become straightforward. ;-) But "identical" really means exactly the same model - the design of most of the half dozen 18-55mm lenses differs enough that becoming familiar with one doesn't help much much with any other if going deep inside. For example, even the AF-S 18-55mm VR and VR II lenses are not very similar with respect to disassembly and parts replacement since they are different design generations. Only the VR and non-VR versions of the AF-P 18-55mm may be close enough for government work but is not yet known for sure. This most likely applies to other lenses as well if going beyond removal of the parts at the back of the lens.
These aren't like your great uncle's SLR lenses - and even those were basically impossible to repair without proper precision tools, most excellent eyesight and/or a microscope, and a steady hand. There are serious high tech parts in Auto Focus (autofocus or AF) Vibration Reduction (VR) zoom lenses including a miniature motor and possibly a gear train, angle encoders and other sensors for zoom and focus, MEMS gyros and voice coil actuators, PCBs with highly integrated ICs including a microcomputer, and many fragile flex-cables and connectors. In short these are complex intricate electro-mechanical systems, not just a bunch of optics! Though even the basic "kit" AF-S DX Nikkor 18-55mm f/3.5-5.6G VR zoom lens has 11 individual optical elements including one that is aspherical, and others like the Nikon AF-S DX 18-200mm f/3.5-5.6G ED VR II may have 16 or more.
And while modern lenses in this class are amazing feats of mechanical design with sophisticated electronics, they do NOT have the look and feel of older "dumb" lenses with milled aluminum focus and aperture rings on well lubricated tracks. ;-) Rotating parts in these lenses are nearly all molded/formed plastic constructed with mostly sliding parts with minimal lubrication and a few rollers (but without frictionless bearings) in a few key places. There is no precision machine work to admire and forget silky smooth operation. Even on a brand new lens, this is obvious when rotating the Zoom Barrel. Having said that, they work remarkably well and provide features like autofocus and vibration reduction that one could only have dreamt about with older gear. I do not know whether high-end modern lenses are constructed any differently, but these are what most of us can afford. ;-) And even they typically have a cost if purchased new of several hundred to over a thousand dollars.
Where there is a Nikon repair and/or parts manual available on-line for the specific model lens, a set of search terms is provided to find it. Should they fail to return anything useful because of decayed links (which is unlikely), I have copies available for the asking. If there is no exact match, a repair manual for a slightly different model lens could prove useful even if the details are not same. But the "repair" manuals are really just disassembly and reassembly manuals with little to no diagnostic information, no explanations of principles of operation, and generally don't go down into the nitty-gritty where the real challenges are in putting things back together. Even the "parts" manuals do not break the lens down below the level of the core (where much of the optics and VR assembly is). They are partially in Japanese and make many assumptions about the user's level of expertise. And while theinfo on alignment - often required after replacing some parts or even just reinstalling them - is quite detailed, it assumes the use of Nikon proprietary jigs and software. But there are numerous diagrams and photos, though none provide the level of detail below with respect to AutoFocus (AF) and Vibration Reduction (VR) implementation. In fact, over half of the typical manual is devoted to the post-repair calibration.
The largest collections of on-line repair and parts manuals for Nikon equipment appears to be at Learn Camera Repair and possibly also at All About Photographic Lenses. That Web site can be searched which will probably be quickest and the manual downloads are all free. However, some others may have manuals not there. They may not be free so make sure that a free download site hasn't been overlooked. Even so, sometimes there are enough free "Preview" pages to be useful. Or the typical cost of under $10 may be worth it if you are really serious about tackling a dicey repair.
Most of the lenses discussed here have "Vibration Reduction" (VR) - a "Steadicam" of sorts inside the lens - which reduces the effects of camera shake especially for telephoto shots. Most popular lenses today have this feature. However, VR is not a cure-all for an unsteady hand. It can only do so much. If one comes to depend on VR and not pay attention to keeping the camera steady, the results can end up worse than without it.
One would think that the non-VR lenses with the same name will be mechanically similar and thus the descriptions, etc. will also be similar sans references to the VR components. Apparently, this is not so. For example, comparing the repair manuals for the AF-S DX Nikkor 18-55mm/F3.5-5.6G VR and AF-S DX Nikkor ED 18-55/3.5-5.6G show them to differ significantly, possibly because the non-VR version is an older design. (The ED II version may be somewhat similar though.) Perhaps for lenses sold today, they would be similar. But manuals for those are not available on-line yet.
Note 2: The names for the same lens may differ subtly in various locations in this document, and in the photos and Web Albums. In some instances this is because characters like "/" cannot be used in a filename. But most often it's that I was not consistent when originally assigning names and am too lazy to go back and correct the 75 places where they are screwed up. The differences are irrelevant and anyone with at least the intelligence of a carrot should be able to figure out to which lens they apply. Live with it. ;-)
However, before embarking on a construction project, there are indirect ways of determining that VR is at least active. On older lenses like the AF-S DX 18-55mm f/1:3.5:5.6G VR there will be a distinct click when the shutter button is pressed and another a second or or so after it is released. This is the mechanism that locks the VR lens group first disengaging and then reengaging. On newer lenses like the AF-S DX 18-55mm f/1:3.5:5.6G VR II or AF-P DX 18-55mm f/1:3.5:5.6G VR there is no lock mechanism but a very faint click may still be audible. Associated with either may be a just noticeable jump in the viewfineder or live view image as the VR engages and disengages. However, a significant shift in the image is probably bad. And for all VR lenses, a faint buzz or white noise will be audible with ones' ear pressed against the barrel of the lens after focus lock but before VR turns off. This is the VR servo doing its thing. These don't prove VR is actually working correctly but are a good indication that it is not dead. Of course check the position of the VR ON/OFF switch if any, move it back and forth a dozen times. If That doesn't do anything or if it is intermittent after excercise, clean it using an environmentally-friendly solvent by removing the switch plate if possible (typically one tiny screw) taking care not to stress the flex cable. If it's part of the Fixed Shell, it will be necessary to go inside. Do NOT just spray from the outside or dunk the lens in solvent. Some cameras may have a VR enable option in one of the menus. But VR works on other similar lenses, the problem is in the lens.
And on one lens, something inside made a loud grinding noise when the camera or VR switch was turned on as though VR was attempting to initialize but perhaps getting bogus data back from a gyro. VR did not work on that lens. ;(
Having said that, the VR lens exerciser is a simpler version of what Nikon uses to test and adjust VR lenses, It consists of a platform mounted on springs or rubber feet for the camera with lens and some means of introducing controlled pan and tilt vibration over a range of frequencies - perhaps a small motor with an off-center weight or a voice coil driver. A remote shutter button would enable the shutter to be half depressed without adding vibration of its own.
The prototype consists of an aluminum plate with soft rubber grommets near the corners to act as compliant feet and several 1/4 inch holes with which a camera can be attached to more or less put the platform's center of gravity in the center depending on the attached lens. A small DC hobby motor with an off-center weight generates the vibration. It can be mounted at various locations and orientations and these will determine how the rig moves. Which one is best is still being investigated. See Nikon Lens Vibration Reduction Tester 1. The location shown creates circular motion exercising VR in X and Y.
The platform wobbles nicely - too nicely as the amplitude can easily exceed the capabilities of the VR system. ;-) And it's almost impossible to determine anything definitive through the viewfinder or using Live View on the camera's LCD: Everything shakes which obscures the effect of vibration reduction. While it's possible to connect to a PC via USB, the update rate may not be adequate. So, an external monitor is required and this works quite well using either the A/V or HDMI output on those cameras that have Live View with real time video. The effect of VR is very obvious and the limits of its capabilities can be easily explored by adjusting the amplitude of the wobble. See AF-S DX 18 200mm f3.5-5.6G VRII VR Test1. This starts with the VR switch OFF and then approximately half way through it is turned ON. See the typical photos in Vibration Reduction Effectiveness for Long Exposure - Off and On Comparison 1. Since the amplitude of the vibration for these tests is near the limit of what VR can handle, the result is not perfect. But the improvement is still dramatic. And I figured that using an antique camera as the subject would be fitting. ;-)
What is strange though is that the behavior of VR on two different cameras (D5200 and D5600) and with multiple lenses does not agree with either the user manuals or the comments on various Web forums: For several lenses tested, the VR state is determined solely by the setting of the VR switch on the lens. Pressing the shutter button makes no difference and the expected "click" indicating that VR is being locked or unlocked occurs only when moving the switch on the lens back and forth. However, the D5200 has known issues with respect to the shutter button so this may be related. But on the D5600 which has a menu setting to turn VR on and off, the OFF option is grayed out for the AF-S DX 18-200mm f/1:3.5-5.6G VR II lens. I have read that some experienced photographers prefer VR to be off under certain conditions including when shooting on a tripod. Perhaps they are concerned about electrical noise causing random movement of the VR mechanism fuzzing up the photos even when VR shouldn't be doing anything. So the switch on the lens must be set to OFF.
Nikon Lens Vibration Reduction Tester 2 shows the complete setup which uses a D5200 with an ancient (pre-digital and otherwise mostly useless) LCD TV to display the real-time NTSC output. While there are many mini-LCD displays available with both A/V (RCA) and HDMI inputs, I have not found an inexpensive one that supports the ~4:3 aspect ratio of the camera's output. So the oldie but goodie here is being used for a noble purpose. ;-) The lens being tested is an AF-S DX 18-200mm f/1:3.5-5.6G VR II. The wired shutter release was thought to be useful to avoid vibration but for some reason, it won't engage autofocus. Perhaps it doesn't have the half-depressed contact. A wireless remote shutter release (IR for the D5200) does. The gizmo with the knob is a digitally adjustable DC-DC for the motor. The off-center weight can be seen to be spinning and indistinct in this several second exposure, yet the real-time display of the antique Nikkormat is fairly sharp.
Prototype #1 uses a 555 timer for the master clock, a two bit shift register to generate the two phases in quadrature with a reversing switch, and a discrete totem-pole driver and ferrite transformer with a 10:1 turn-ratio. for each phase dug up from the depths of a junk box. See the circuit at Sam's Nikon AF-S Lens SWM Tester 1 Schematic. The TTL phase generator was built on a prototyping board with the HV drivers on a solderless breadboard as shown at Sam's Nikon AF-S Lens SWM Tester 1 Prototype V1. The phase generator is at the upper left with the high voltage driver below it. The POW PCB from an AF-S DX f/1:3.5-5.6G VR zoom lens can be seen at the upper right. ;-) The extra space on the prototyping board is for the final driver circuit if that ever happens. In the meantime, the stuff on the solderless breadboard was moved to a smaller phototyping board and bolted to the large one as shown in Sam's Nikon AF-S Lens SWM Tester 1 Prototype V2 and Tyical Waveform. The shape of the waveform is quite similar to that of the Nikon driver. And yes, if one looks carefully, the physical driver circuits are not quite 100% identical to the schematic. ;-)
But think of this as a "simple" generic circuit and not something to copy directly since it is marginal in the voltage department, assumes the use of transformers that one can't buy at Digikey, and the transistors should probably be replaced with higher power devices as they do get hot especially toward the upper range of the test conditions. But V3 below would be worth considering though the transformer would still need to be custom wound.
Having said that, the frequency range is from 15 kHz to 300 kHz and the maximum output voltage is above 200 V p-p up to around 70 kHz and decreases above that. So this would probably not work for the SWM in lenses requiring a higher driver frequency unless their voltage requirement is much lower. And 200 V p-p is well below what has been measured for a sample lens (AF-S DX 55-200mm f/1:4.0-5.6G VR, see the info on the "Lens Test Rig", above) of ~240 V p-p. But even 150 V p-p is more than adequate to drive the SWM used for these tests (at low speed at least) if set close to the optimal frequency. For the test SWM from an AF-S DX 18-55mm f/1:3.5-5.6G VR "kit" lens, this turned out to be 73 kHz. Even as low as 100 V p-p more or less worked when the SWM was in a good mood. It's a minor miracle that these transformers even came close to being useful as they are left over from some sort of SMPS project (not even my own). And they are only about 125 times the volume of the transformers in the actual lens. ;-) An attempt was made to add turns to the secondaries to see if the voltage could be boosted, but that did not result in any uesful improvement and actually made things worse, eventually blowing the drive transistors when pushed too hard. This is complicated by the fact that the SWM is a largely capacitive load, measured at 1.3 nF for the one in the AF-S DX 18-55mm f/1:3.5-5.6G VR lens. The capacitance kills the output from and shorts the input to the typical ferrite transformer designed for use in inverter-based HeNe laser power supplies. To get higher voltage from the same circuit would probably need both better driver transistors and more copper (primary and secondary turns) in the transformers as they are saturating at the upper limit of the input voltage range. But the waveforms this circuit generates are remarkably similar to those shown in Example Nikkor AF-S SWM Drive Waveforms for Phases A and B. (In the interest of full disclosure, the blue trace was measured but the yellow one was just copied as the naked lens had only a single working phase.)
A slightly simplified version was also prototyped. See Sam's Nikon AF-S Lens SWM Tester 2 Schematic. However, its performance is similar. But never fear, help is on the way. ;-)
What never ceases to amaze me is that the tiny PCB, with dimensions of 1-1/4x3/4 inch and its 3/8th inch square ferrite components running off 5 V or less can drive the SWM at full speed without working up a sweat! And ohmmeter tests suggest that they do use simple transformers to generate the high voltage output. There are only two pairs of connections to them with resistances of around 0.1 and 12 ohms, respectively and they do not share any connections. One end of the output goes to the SWM; the other goes the center pin of an SO3 part with another lead going to GND. So it may not be magic after all. Also, photos of the PCB from an AF-S 24-70mm lens show E-E core magnetics with exposed windings that look like transformers. ;-)
Further, a patent search for "Nikon Silent Wave Motor" turns up in at least a half dozen with the following circuit: Driver Schematic for SWM from Nikon Patent. And this bears a remarkable resemblance to what is actually present in every AF-S lens model I've dissected, though the transformer turns ratio may be greater than 50:1 and not 1:1. Confirming that will be a PITA due to their small size.
Looking at the circuit closely, it would appear to be somewhat similar to a flyback driver. When the input phase is positive turning on the primary-side MOSFET, current builds up in the primary but secondary current is blocked because its MOSFET is off. When the input phase goes negative, current ceases in the primary, the magnetic field collapses and transfers its energy to the secondary which has its MOSFET turned on, so the current flows out to the SWM electrode (capacitor). The output voltage gets a boost both from this burst of current and the turns-ratio. I'm still stuck with the same transformers but found one where the core can be separated so a spacer can be added to increase the leakage inductance if necessary, as in a real flyback converter.
(An alternative that also shows up in an early Nikon patent (US5179311) is what may be described as a "resonant charge pump". But that requires the two coils to be joined and other parts that don't appear to be present on the POW PCB.)
A funny thing happened on the way to prototyping the quasi-flyback topology. See Sam's Nikon AF-S Lens SWM Tester 3 Schematic. With only the primary-side driver and adjustment of the core gap, the output almost doubled compared to V1 and V2. So with 15 VDC input, the output is 240 V p-p and at 20 VDC input, it is over 300 V p-p, both using the 1.3 nF simulated SWM load. This is roughly 16 times the DC input voltage. And this circuit is so dirt simple. The 2N5551 is a high voltage (160 V) bipolar transistor needed because when it shuts off, more than double Vss appears across its C-E. But if Vss is limited to 15 VDC, a 2N3904 would probably be just fine. The 2N5551 doesn't even get warm. The purpose of the capacitor and diode in the base circuit are to prevent the transistor from shorting the power supply if the input signal get stuck high. A current limiting circuit using an LM340 could also be added for overall protection. The transformer core gap is somewhat critical for maximum output. However, it appears as though Murphy was on vacation so pieces of 1.6 mm (1/16") PCB material turned out to be near optimal to generate the maximum p-p output for a give Vss at the 69 kHz drive frequency. But the core gap is probably at least somewhat sensitive to frequency as well as load. AND the waveform looks even more like that of the Nikon driver! ;-)
However, I did not anticipate the following when constructing the dual phase driver on a single board:
Sam's Nikon AF-S Lens SWM Tester 3 Output Phase and Shape versus Drive Frequency is an animated GIF showing what happens over a relatively narrow range of frequencies below and above the optimal 69 kHz. No, I'm not doing an actual video! ;-) Below 69 kHz, the shape "snaps" between the top two scope traces as the frequency is changed; Above 69 kHz, the transition is gradual but there is an unstable region as shown where it oscillates between them. Over the full ~9 kHz range, the relation between the drive and output phase changes by at least 90 degrees. Within the range where the shape has the double lump, the output voltage is near maximum and relatively constant, but declines on either side. These tests were done with a single driver without a second transformer in the vicinity so there are no coupling effects.
(1) can be dealt with most easily by separating the transformers and mounting them so their fringe fields are at right angles to each-other (or perhaps with a shield). (2) requires careful tuning of the core gaps. Both of these can be achieved at the same time but it is a bit annoying. However, coupling could be reduced to manageable levels by simply rotating one of the transformers by 90 degrees to separate the core gaps. The exciting exploration of all this is left as an exercise for the bored student. But with care, at least 300 V p-p is possible before one or both waveforms gets corrupted. However, to achieve that p-p output voltage, the input voltage must be increased from 0, not switched on suddenly, and if the thing switches to weird mode, the input voltage will probably need to be reduced to 0 V to recover. Got that? ;-)
Given that this is only for testing and would never fit inside a lens anyhow, there is little point in adding the secondary-side components and thus there isn't likely to be a V4. ;-) For anyone handy at winding simple transformers, V3 would be recommended even with the fiddly adjustments. The only additional construction that was undertaken is a single copy of the boost circuit just to have something more "compact" to demonstrate without strange behavior using an external clock and scope. ;-)
CAUTION: If these steps are not performed in the exact order shown, the Camera Contact flex cable may be torn rendering the lens useless.
CAUTION: On some lenses, the zoom range is restricted by the presence of the back shell. Bad things can potentially happen if zoom is changed and it goes beyond the lower or upper limit. Namely parts of the lens will fall to bits making reassembly trickier. ;-(
Here is an implementation summary of known DX 18-55mm f/3.5-5.6G zoom lenses. There may be others:
Gener- (1) Auto- Focus Focus Manual Year Model ation Optics Focus Encoder Tachometer Focus Introduced -------------------------------------------------------------------------------- AF-S ED 1 2C/5G/7E SWM Yes Magnetic Mechanical 2005 AF-S ED II 1.5 2C/5G/7E SWM Yes Optical Mechanical 2007? (2) AF-S VR 2 3C/8G/11E SWM Yes Optical Mechanical 2007 AF-S VR II 3 3C/8G/11E SwM Yes Magnetic Mechanical 2014 AF-P 4 3C/9G/12E Pulse No None Electronic 2016? (3) AF-P VR 4 3C/9G/12E Pulse No None Electronic 2016? (3)
The AF-S ED is probably the original AF-S 18-55mm zoom lens. The ED II may be more similar to the AF-S VR without VR than the ED. The non-VR version of the AF-P 18-55mm lens is identical in appearance to the VR version except for the labels and based on a Nikon brochure appears to have the same optics as the VR version.
A montage showing stock photos of all known versions of the 18-55mm kit lenses as of 2022 may be seen at: Nikon AF DX 18-55mm f/3.5-5.6 "Kit" Zoom Lenses. These are from Nikon lens product or review pages (copyright © Nikon Corporation) scaled so the relative sizes are close to correct. Photos of actual specimens coming soon.
Note that the AF-S ED, ED II, and VR lenses have a filter mount that rotates with focus. This can be a pain if desiring to use a linear polarizer to enhance contrast or even an asymmetric lens hood since its orientation should remain fixed. What were they thinking? ;( It is fixed on the AF-S VR II and AF-P lenses.
Diagrams showing the physical appearance and optical architecture of the 3 VR lenses may be found at: Comparison of Nikon DX 18-55mm 1:3.5-5.6G VR "Kit" Zoom Lenses.
AF-S DX 18-55mm VR Zoom Lens Zoom Control:
The following applies specifically to the AF-S DX 18 55mm VR Zoom Lens but others are generally similar. Although the design of the mechanism that moves the internal parts of the lens when zoom is changed may seem daunting, it is really quite straightforward. But putting the pieces back together can be a challenge.
Another challenge has been locating truly broken specimens of these lenses that I'm willing to use for dissection. Lenses listed on eBay as "For Parts or Not Working", "Untested", or even "Manual Focus Only" have turned out to be fully functional or easily repaired without going deep inside. In some cases it's because the lenses are not compatible an older camera the seller used for testing and so appear not to work. For others it's simply because the seller had no camera body to use for testing and they didn't want to risk a return. But overall, the reputation for poor reliability of AF-S lenses appears to be exaggerated. In fact I've yet to acquire an intact sample of a "Parts" AF-S where the SWM (Silent Wave Motor) or driver electroncs were faulty.
More to come.
The ED may be the first of the AF-S DX 18-55mm zoom lenses and not much is known about it other than what is in the repair manual showing significant differences compared to even the ED II version. That version appears to be closer to the AF-S VR lens, below.
The AF-S DX ED has fewer lens elements, uses a magnetic instead of an optical tachometer for autofocus, and the construction is more complex and somewhat clunkier.
I acquired one but since it is in good condition post cosmetically and functionally, it will be for external inspection only, not for dissection. There are no current plans to investigate this lens in greater detail unless someone would like to donate a sacrificial specimen for analysis. The asking prices on eBay are above may curiosity quotient for a lens to take apart and likely never put back together so it functions. ;-) Appropriate chants and incantations will be issued to the gods of dead camera lenses upon request but it will not likely survive the experience. :( ;-)
See the Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G ED Zoom Lens Dissection Web Album. There is no dissection yet but it shows some stock photos, the optical architecture, how the lens groups move with zoom, an engineering diagram of the lens derived from one in the repair manual, and photos of the exterior in various poses. Most of these photos were taken with either a Nikkor 18-55mm ED II lens or the repaired 18-55mm ED lens - ID #2.
Here is a summary of the Nikkor 18-55mm AF-S DX f/3.5-5.6G ED lenses I've acquired so far:
However, there is a hint of how this may have happened on a working specimen of this lens: Pushing on the flare shield from the back can cause its guide post to pop out of the straight channel in which it moves. And it didn't take much for this to happen. The entire assembly then becomes jammed and if forced could conceivable result in the damage that was present. Fortunately, gently coaxing the post back in the channel with a thin tool returned the lens to full functionality with no hint of any trauma.
With all the parts installed but still in the unzoomable state, it was reassembled to see what it would do. The results of that test were mixed. It did attempt to focus and would take pictures of sorts, but they were out of focus and strangely colored. At that point the aperture was not operating and the back lens cluster may have fallen out the bottom again. Aside from those issues, everything was perfect. ;( ;-) But it's likely that the electronics are fine. For all the good that does.
So there are two mysteries here:
If it weren't for (2), perhaps the lack of lubrication would make sense. There must be an obvious cause common to both of these but so far identifying it has proven elusive. This may call for another acrificial lens to compare! ;-) A simple possility is that the destruction resulted in the channels and guides becoming damaged and without the perfect fit, just would not work together.
Additional photos have been added to the dissection Web Album reflecting the extent to which it has been disassembled, and more info should be forthcoming. Stay tuned.
The Filter Ring is in mint condition, so it could be swapped into ID #2. But since that would also swap the front lens groups, it is not known whether there might be collateral image quality issues without the Nikon-certified alignment. And since ID #2 is no longer broken, why fix it? ;-)
Autofocus on this lens as well as the AF-S VR (and probably the AF-S ED II), and other lenses use the SWM to rotate a plastic ring with two prongs (tips of a fork) that slip into slots in the Filter Ring, which serves to adjust focus by moving in and out via internal helical grooves. On this sample of the AF-S ED lens, two of the raised bits of plastic that are the stops on one side of the slots were sheared off. While they aren't that large, it still isn't clear how this could happen. Possibly a gorilla attempted to change focus using the Filter Ring while in autofocus mode. Or perhaps there was a control problem resulting in the fork bashing against one end repeatedly. However, testing after the repair (below) did not indicate any such issue.
The broken protrusions are only about 1/16" on a side. But a replacement can be long since there is nothing in the way around the periphery of the Filter Ring. However, gluing plastic is always dicey so I opted to install a pair of 0-80 x 1/16" cap head screws in place of the broken-off plastic bits.
Since the repair manual is fairly detailed for this lens, it may come in handy here to clarify the disassembly/reassembly process.
Nikon AF-S DX Nikkor 18-55mm 1:3.5-5.6G ED Zoom Lens Filter Ring Focus Repair shows the normal appearance and after the repair. Sorry, I forgot to take a pic of the original condition. :( ;-)
If they are correctly engaged, the problem is elsewhere.
CAUTION: Do the testing over a padded surface in case the orientation of the Filter ring is not correct as it may pop off during auto or manual focusing and fall out. That has happened to me a couple of times fortunately resulting in only minor cosmetic damage but it could have been much worse. ;-(
There was some free play when this lens was reassembled because the 0-80 screws weren't quite positioned perfectly. Can you believe that? Geez, they are at least as large a grain of rice. ;-) Also, the heads of the only suitable screws available were ridged, not smooth and after 10,000 years of continuous shooting that could conceivably result in excessive wear of the Focus Fork tines. Of course as a practical matter, neither would likely make the slightest difference in anything including the longevity of the Universe, but being somewhat OCD about such things, a layer of Epoxy was added around the screw heads to to smooth and fatten them up a bit. ;-)
After around the fiftieth time removing and replacing the Filter Ring, it becomes almost trivial. ;-)
The ED II is the successor to the ED. Originally I though it may be closer in mechanical design to the AF-S DX 18-55G VR that followed. However, that turns out NOT to be the case. In fact, while the shape of the outer housings (Zoom Ring and Fixed Shell resemble those of the VR, internally, the core optics assembly appears to be identical to that of the ED physically at least and it is swappable between them. Whether the actual lens elements there and in the front lens cluster are any different is not known. The major change is that a single PCB replaces the 3 PCBs in the ED lens. Both the ED and ED II have only 2 lens clusters and for that reason, changing zoom requires noticeably less effort than for the lenses that followed. At least for the functional samples I have (which excludes ID #4, below). In fact, these may barely hold zoom if oriented vertically.
Investigation of this lens in greater detail can now proceed as a suitable sacrificial specimen has been acquired. ID #4 is in dreadful enough shape mechanically with parts missing that only low cost chants and incantations to the gods of dead camera lenses have been required.
See the Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G ED II Zoom Lens Dissection Web Album. There is no dissection yet but it shows some stock photos, the optical architecture, how the lens groups move with zoom, and photos of the exterior and with it partially unclothed in various poses.
There is a repair manual on-line for this lens. Search for "Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6 VR Zoom Lens Repair Manual" (without the quotes). It's the first hit using Google.
This was the "standard" lens on older D3xxx, D5xxx, and other low to mid range Nikon DSLRs using the DX format (~1x0.6 inch) sensor But there seems to be little standardization among lenses that may appear to be very similar like the AF-S 18-55mm and 18-70mm, which have very little in common in terms of construction. The AF-S 18-55mm has now been replaced with the AF-P version which uses a different type of autofocus motor which simplifies the construction, and is slightly more compact. A description and dissection of that lens is later in this document. But while larger lenses like the 18-200mm are generally similar in construction, the details will differ substantially. A section on those may be forthcoming but even totally broken ones tend to have a cost on eBay above my curiosity quotient. ;-) And there is a Nikon repair manual on-line for the older version of that lens (non-VR-II).
Further, many lenses like the one in this section are made largely of plastic. The only major structural part made of metal is the cylinder with tracks to guide the extension of the focus and zoom lens groups. (Right of center in the photo above.) And the more recent lenses (AF-S VR II and AF-P VR) have even replaced that with plastic. So it's easy to break parts or strip threads for tiny screws. In fact, the guide rollers which control the extension of the focus and zoom lens groups are plastic, and at least one was found to be fractured in the discombobulated lens used for the photos. It can be seen among the pile of teeny hardware bits.
But these are very high tech devices.
Most of the photos referenced below are also available as a Web Album (though possibly at slightly lower resolution) at Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Parts Web Album.
There are a pair of Epson MEMS-based "XV-3500CB High-Performance Low-Power Yaw Rate Gyro Sensors" to provide the signals for pitch and yaw from which the feedback electronics can drive the VR actuators. The two 8 pin chips can be seen attached to the large cylinder physically 90 degrees apart, near the right-side in the photo above.
Angle encoders for focus and zoom consist of gold-plated patterns with spring contacts to tell the micro-brain what the approximate settings are. These would be used by the control system to know which direction to be able to move and to adjust feedback parameters like loop gain. They can be seen attached to the same assembly as the MEMS sensors are on. The patterns are designed so that no more than one transition can occur simultaneously to avoid ambiguity, though they do not use the common Gray code. This was probably done to minimize the number of patterns or stripes and thus conductive brushes. Those in the Nikkor AF-S DX 18-55mm VR or VR II lenses have 6 data bits but only 2 or 3 conductive stripes (plus a common stripe) providing fewer than half the possible states. More on this below.
For reference, here is the standard Gray code for six bits:
Dec Binary Gray Dec Binary Gray Dec Binary Gray Dec Binary Gray -------------------------------------------------------------------------------- 0 000000 000000 16 010000 011000 32 100000 110000 48 110000 101000 1 000001 000001 17 010001 011001 33 100001 110001 49 110001 101001 2 000010 000011 18 010010 011011 34 100010 110011 50 110010 101011 3 000011 000010 19 010011 011010 35 100011 110010 51 110011 101010 4 000100 000110 20 010100 011110 36 100100 110110 52 110100 101110 5 000101 000111 21 010101 011111 37 100101 110111 53 110101 101111 6 000110 000101 22 010110 011101 38 100110 110101 54 110110 101101 7 000111 000100 23 010111 011100 39 100111 110100 55 110111 101100 8 001000 001100 24 011000 010100 40 101000 111100 56 111000 100100 9 001001 001101 25 011001 010101 41 101001 111101 57 111001 100101 10 001010 001111 26 011010 010111 42 101010 111111 58 111010 100111 11 001011 001110 27 011011 010110 43 101011 111110 59 111011 100110 12 001100 001010 28 011100 010010 44 101100 111010 60 111100 100010 13 001101 001011 29 011101 010011 45 101101 111011 61 111101 100011 14 001110 001001 30 011110 010001 46 101110 111001 62 111110 100001 15 001111 001000 31 011111 010000 47 101111 111000 63 111111 100000
Here is a closeup of the actual focus encoder color coded and labeled with the binary value at each position: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Focus Encoder Coding. While it has 6 bits, there are only 29 states. Interestingly, the codes for the near and far end-zones are complements of each-other, which is probably a coincidence but perhaps not. ;-)
The Zoom encoder is longer because the Zoom Barrel moves over a larger angle than the Focus Ring, but it's also wider. Here is a closeup of the actual zoom encoder color coded and labeled with the binary value at each position: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Zoom Encoder Coding. Like the focus encoder, it is a distance-1 code (but not the same one) with 6 bits but only 31 states. The common contact is on the opposite side of the coding strips for some unfathomable reason, the relative lengths of each code segment along its length may also differ, the code sequence is not the same (even accounting for the strip position swap), and there is a larger number of states. Aside from all the differences, everything is identical. ;-) Note that since the photo of the zoom encoder strip was taken in situ and it covers a large angle, the areas near the ends are squashed by perspective - the codes should be more spread out than they appear there.
What isn't clear is why the patterns are non-uniform. It would make sense for them to not have a relative spacing based on the sensitivity to change depending on the focus or zoom position. But all the encoders so far analyzed have seemingly arbitrary variable spacing. Further, in comparing the patterns for several AF-S lenses, no two are the same (even accounting for the required length and available space). Since the code is almost certainly mapped through a lookup table, the absolute values should not be relevant. Go figure. ;-)
Movement of the lens elements for autofocus in these AF-S lenses doesn't use a conventional motor with magnets and coils like in the good old days. ;-) Rather it uses a motor based on the piezo-electric effect, which is property of some types of crystals to deform when a voltage is applied. The most commonly used crystal is lead zirconate titanate (Pb[Zr(x)Ti(1-x)]O3), usually abbreviated "PZT". This is the same stuff used for the obnoxious beeper elements found in all sorts of electronics. PZT may also be used as an abbreviation for PieZo Transducer, the device itself, which is convenient. ;-) The focus motor is driven at a frequency beyond the range of human hearing and thus similar technology is called "Ultrasonic" by other manufacturers based on the name for the actual motor technology. (Some are called "Hypersonic" which makes no sense at all.....) So focusing should be very quiet - except perhaps for the bats you're attempting to film. ;-) (The "S" in AF-S supposedly stands for "Silent", so all AF-S lenses should use similar technology. However, even if the motor itself is silent, the gears still makes a sound and other parts of the lens may not be quite silent. Nikon calls them: "Compact SWM","Gear SWM", or "Micromotor SWM" where "SWM" stands for "Silent Wave Motor". Much more on this below. Upon first examination, the motor in the AF-S lens appeared to be very strange without any detectable magnetic field and with the rotor almost locked in position, held in place against a plate by a strong spring, more like a clutch than a motor. Furthermore, all combinations of the red/yellow/black wires tested open and applying low voltages to them resulted in absolutely nothing, not even smoke. ;-)
There are two types of ultrasonic piezo motors used in Nikon lenses: Gear motors and Ring Motors. Piezo motors have advantages and deficiencies. For a brief description with photos (but little explanation), see Two types of motors 'Nikon SWM' (RADOJUVA). In this document, the acronym "SWM" will usually refer to the gear motor variety.
CAUTION: If disassembled for cleaning, take care using a solvent in the area of the conductive adhesive bridge. Even isopropyl alcohol may remove it. A suitable conductive adhesive is expensive for the tiny amount needed. ;( ;-) Perhaps a couple loops of fine bare wire wrapped around the stator and tensioned would be a suitable substitute.
Gears are still needed to provide adequate torque to rotate the focus ring reliably, around 3:1 down from the motor to the white pinion gear. The ratio is around 1:3 up from the motor to the slotted tachometer disk. Count the number of teeth on each gear for precise values. ;-)
The capacitance of each of the two phases was measured to be approximately 1.3 nF. Attempting to drive the motor with a function generator and 1 nF capacitor in series with one of the inputs to shift its phase resulted in absolutely nothing happening at the ~20 V p-p maximum output of the function generator over a range of less than 1 kHz to greater than 100 kHz. So actual high voltage is needed. Measuring the voltage on this lens is regrettably not viable since it's in bits now and was never in a usable state even before it was disassembled. More later.
However, guessing that there would be enough leakage from the high voltage components, a sense coil was constructed using a 3 turns of hookup wire and connected to an oscilloscope probe. It was then possible to easily measure the PZT drive frequency for a similar lens. The coil was simply placed under the lens - which turns out to be approximately where the piezo motor and POW PCB are located. A distorted triangle wave with a constant frequency of around 77 kHz and amplitude of over 80 mV p-p appeared on the scope only when the focus ring was moving. The waveform shape changed slightly based on direction, but who knows how the coupling (which is probably mostly from the ferrite transformers) affects it. So 77 kHz does indeed qualify as ultrasonic. ;-)
(In fact during inspection of the innards of the AF-S 55-200mm VR lens described along with a dissection in a later section, the two signals were brought out so they could be measured with the lens on a camera. The voltage turns out to be approximately 240 V p-p at around 70 kHz so it's not surprising that 20 V p-p from the function generator did squat. This lens uses the same or a very similar SWM so the amplitude should be similar. The slight difference in frequency is probably of no significance. The Nikon lens designers like to play with the SWM frequency even among lenses that are physically similar.) One Phase of AF-S SWM Drive Waveforms. shows the actual measured waveform for one of the phases. Since only one of those signals was working, here are Example Nikkor AF-S SWM Drive Waveforms for Phases A and B with both present. The direction of rotation is determined by the relative phase of the two signals where A leads by 90 degrees or lags by 90 degrees. One waveform was actually measured while the other was MSPainted in. ;-) If and when this lens is repaired, actual waveforms for both phases will replace these. Nah. ;-)
Using a sense coil and scope may be a decent diagnostic test to determine if AF-S autofocus failure is due to a mechanical problem or lack of the PZT drive signals. If no signal can be detected, or if there is only one phase, then it's probably an electronics or control problem. While what is sensed through the air will not be as clean as the directly measured waveforms and determining if both phases are present will be more challenging even if an identical sample of a working lens is available, the presence of a strong signal is indication that most of the circuitry is working.
Perhaps the key to understanding how this works lies in the "W" of SWM - Silent Wave Motor. This type appears to be what's called an "Ultrasonic Motor" operating at the resonant frequency of the structure, around 77 kHz as measured above. Each set of 4 segments connected to the same input lead if duplicated around the stator would result in a total of 8 more or less equally spaced equal length segments. The two sets appear to be physically offset by 90 degrees. Each set if driven by itself would create a standing wave around the stator. But if both sets are driven the result is a traveling wave whose direction depends on their relative phase with a net torque in that direction. Another way to think about it is with an analogy to those magnet and coil motors, specifically two-phase induction motors. These have two sets of coils that are offset from each-other physically by 90 degrees. The relative electrical phase of the power applied to the two coils then determines torque and direction of rotation. The reasons for the conclusion with respect to this piezo motor are (1) the diagrams and photos of ultrasonic motors from a Web search have a similar slotted architecture, (2) they also have only 3 connections, and (3) the explanation in Survey of the Various Operating Principles of Ultrasonic Piezomotors, K. Spanner seems to fit. But the details are still somewhat of a mystery. Nikon has a bazillion patents on autofocus using the SWM, mostly Japanese though Google does a half decent of translation. Two US patents are US8035906B2 and US20200350838A1 which seem to be close in appearance to this motor, even down to the number of segments on the slotted disk and precise pattern of the PZT elements. These come up or are referenced when searching Google Patents for: Nikon "Silent Wave Motor". Reading patents is always a treat though. :( ;-) If anyone can shed more light on the principles of this motor, please contact me via the Sci.Electronics.Repair FAQ Email Links Page.
Interestingly, the repair manuals for all the AF-S lenses found on-line make a specific note to not touch the area of the piezo motor. With high voltage involved, that may be good advice, but this in reference to disassembly and reassembly where the lens is un-powered. So, it probably really refers to avoiding contamination which may cause electrical leakage and a reduction in drive voltage as well as possible actual damage "gumming up of the works" after running a long time like what is seen here. Perhaps that is why AF-S lenses have a reputation for autofocus failure - with no sealing of any kind, dampness is getting in over time providing a leakage path so the motor eventually stops working reliably. This lens almost certainly had that failure.
One subsequent observation is that the drive frequency may need to be tuned to the specific SWM. Even identical lenses may have slightly different drive frequencies and the reason became obvious when constructing an Silent Wave Motor (SWM) Test Rig which provides a way to drive the SWM disconnected from the lens. The sensitivity to drive voltage is a strong function of frequency. What this means is that swapping the POW PCB (which generates the high voltage SWM drive) or even the CPU PCB between lenses may result in sub-optimal performance or no function at all.
As if that wasn't exciting enough, here is the good (VR) stuff. ;-)
Left photo: Solder globs for the fat traces to the two coils that move the lens are visible at the bottom and left. The set of 6 fine traces appear to be for a pair of Hall-effect sensors (stuck under the Kapton bumps at the top and right positions).
Right photo: Solder globs for the fat traces to the locking coil (see below) are visible at the top. The metal plate is one of the magnet pole pieces.
Left photo: The two coils that move the 3rd group lens element are readily visible. There is a rare earth magnet under each of the coils. A quick test with a 2 V power supply confirmed that the lens does indeed move from side-to-side in two axes as expected, but doesn't tilt. Two springs to keep the lens in place are also visible at the upper-right and lower left. The metal squares at the top and left are glued to rare earth magnets to bias the Hall-effect sensors which would be located directly behind them if the original flex-cable was still in place. But one of them fell off without any provocation. Gluing metal to plastic doesn't work well. ;( ;-)
Right photo: The large metal plate acts as a pole piece for both of the lens element positioning coils. A third coil using an additional pair of magnets hidden under the pole piece is used to rotate a collar to keep the movable lens centered and to prevent it from wobbling on its own due to vibration when VR is OFF. The leaf spring to keep it locked without power is visible at the right. The yellowish metal block at the upper-right is probably just a counterweight for this assembly and is probably made of brass to be non-magnetic.
There must be some pretty fancy footwork going on in the algorithms on that CPU board to actually implement the VR. And the lens element must be maintained centered electronically when VR is on using the Hall-effect sensors for feedback. There is no restoring force so it will tend to sit at the lowest point. When VR is off, it will be more or less centered using the locking collar. The springs only keep it against the surface of the front cover.
And you thought camera lenses were boring. ;-)
Here is a summary of the Nikkor 18-55mm AF-S DX f/3.5-5.6G VR lenses I've acquired so far:
Though I do not have an intact sacrificial lens at present, I will be hunting for one. Of if someone would like to donate one, it will be immortalized. ;-) So, there should be more to come soon.
It is best to set each subassembly aside along with its screws in a plastic bag or some other safe place. There are at least a half dozen different size/types of screws and using the wrong one can strip a threaded hole. Note: An attempt was made to use names from the repair manual, so some may seem strange. ;-)
CAUTION: Do NOT remove the back lens group (called the "4th lens-G unit" in the manual) if intending to reassemble the lens into a fully to-spec state unless closeup photos are taken so that can be replaced in exactly the same position. Else it may require Nikon to align it for only 5 times the cost of a replacement lens. It is secured with 3 screws and washers, sealed with something like Loctite™.
Back of lens
Front of lens
More to come.
The parts are shown in: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Focus/Zoom Guide. The stud with the rollers is secured through the Fixed Barrel of the lens with the screw on the left with the offending roller missing as will likely be the case with this failure. Both are present next to it, and only a roller on the right. I'm calling them "rollers" though it's not clear if they are intended to actually rotate or just slide within the focus and zoom tracks. When fractured, it's likely that some pieces will break free and float around in the lens interior or perhaps fall out through the back.
This is among the simplest lens repairs not even requiring any precision tools. That is, assuming replacements for the broken plastic pieces are available - most likely only from a sacrificial AF-S 18-55mm VR lens or other similar small lens (though that is probably not very likely given Nikon's tendency to reinvent everything with each new model). In principle, it is possible to fabricate replacements but they probably won't be found on eBay or anywhere else at affordable prices or at all. Also note that there are 2 sizes of these roller thingies on the same shafts in this lens - the larger ones control movement of the Inner Barrel with Lens Groups 4-8 while the smaller size (relevant here) is for Focus. They are not interchangeable. The smaller size is the one needed here unless both are broken. But the procedure for replacing the larger ones may be considerably more involved as they will be captive by the Focus Barrel and likely requires much more extensive and tricky disassembly.
The broken pieces are at the front of the lens and the disassembly is relatively low risk. For some of this, the repair manual (above) provides help with photographs, but it goes much deeper than needed for this repair, and getting carried away removing stuff can ruin your entire day. It is also NOT even necessary to remove the lens cap, which should be left in place to protect the front glass.
Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Missing Guide Rollers shows a view inside the Zoom Barrel where 2 of the rollers are missing from the ridged studs.
CAUTION: Do the initial testing over a padded surface in case the orientation of the Filter ring is not correct as it may pop off during autofocusing and fall out. That has happened a couple of times fortunately resulting in only minor cosmetic damage but it could be much worse. ;-(
One mystery with the lens (ID #3) used for this description is that there were no signs of broken roller bits inside and the lens does not appear to have been opened previously. So they may still be inside somewhere waiting to cause havoc or fell out the back. There was a fair amount of dust inside which says something about the lack of decent seals on these things. ;( ;-)
Out of curiosity, I puchased a supposedly defective sample of this lens where the trim ring had popped off as shown in: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens with Loose Trim Ring. It looked bad and for that reason the price was right, but was easily repaired. See the section: Repairing Loose Trim Ring on Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens.
While searching for another one to dissect, measurements of the SWM frequency provided a clue as to the design changes. A 6 turn sense coil was placed under the lens, which as before was determined to be the optimal location for a strong signal, probably in close proximity to the ferrite HV transformer(s). Rather than 77 kHz as in the original AF-S lens, the frequency for the AF-S II is around 290 kHz (!!) which was originally assumed to indicate a much smaller motor (though this turns out not to be the case, more below).
When the focus ring is moving, the pulse width may be up to around 700 ns. But there is still a detectable very stable ~100 ns spike at the same frequency with similar amplitude for several seconds after the camera has beeped indicating that optimal focus has been achieved, not only while the focus ring is moving. So it is likely from the same source and not just pickup from the logic, perhaps a sort of dither to minimize stiction in the mechanism between focus operations.
But it turns out that the SWM itself appears to be physically identical in both lenses. And the gear reduction is also similar. Then I thought perhaps the higher frequency was selected to be able to smaller magnetic components, but this also turns out not to be the case. So my conclusion now is that the higher frequency may have been selected primarily because it permits faster focusing or because of complaints from local bats. ;-)
The physical size reduction of the VR II lens is thus accomplished by mostly clever packaging. ;-)
Here is a summary of the Nikkor 18-55mm AF-S DX f/3.5-5.6G VR II lenses I've acquired so far:
Note that for the following, the Fixed Barrel, Fixed Shell, Metal Ring/Shims/Insulator/Spacer, and Bayonet Mount are all one structure secured from the back by the 3 larger screws. The Zoom Barrel rotates around the this and the lens clusters/groups move with respect to it.
Please refer to the Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Dissection Web Album and Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Parts Identification. Not everything is labeled but these should be a start.
Set aside each set of screws with their respective parts as there are several different size and length screws involved here.
This is from memory so some details may be a bit fuzzy. ;( ;-)
It is highly recommended that match marks be added at each step where a major piece is removed as the quasi-3-fold symmetry can greatly confuse things. The only part with true 3-fold symmetry may be the Trim Ring. ;-) All the others can be put together correctly or at all with only one specific orientation. And this is a lens so take photos at each step. ;-)
Note that this step isn't absolutely necessary unless replacing it or desiring access to the VR assembly.
CAUTION: The magnetic tachometer read head on the focus assembly is on a miniature metal spring suspension so that it is in contact with the magnetic strip - see the dissection photos. It is easily bent and damaged. Take note of its location and be careful when handling the focus assembly. It can usually be repaired if not deformed too badly. Also, magnetized tools in close proximity to the magnetic strip could erase the magnetic pattern rendering it and the lens useless. There are YouTube videos involving replacing that strip on other lenses but you really don't want to go there. :( ;-) A sufficiently powerful magnet (or tape head demagnetizer) near the lens could conceivably do it as well.
If match marks were made during disassembly, this will be a much more straightforward. If not, refer to the dissection photos.
Please refer to the Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Dissection Web Album and Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Parts Identification. Not everything is labeled but these should be a start.
In all the fussing, the plastic mounting post for the SWM Gear broke off at its base. ;-( Repairing that was a pain but appears to have been successful: A slightly under-size hole was drilled in the stump and then the post was press-fit back in place. For the OCD types, adding a bit of non-softening plastic adhesive would have probably been worthwhile. It's a fraction of an inch shorter than the original but should be good enough for government work, especially considering that I have no intention of actually using this lens - ever!
Three 2-56 nuts and washers will be required during reassembly which are not part of the lens. These substitute for the metal rings etc. and Bayonet Mount to secure the Fixed Barrel and Fixed Shell with similar thickness until the Bayonet Mount is installed.
If individual parts like the SWM or PCB2 were removed during disassembly, additonal steps may be required, but they should be self-evident, intuitively obvious, or both. ;-)
If the Zoom Barrel doesn't turn easily, use a thin piece of plastic to depress the (now hidden) pegs for lens groups 4,5,6 (middle lens cluster) just enough so they can slip into their tracks inside the Fixed Barrel while gently twisting the entire combined unit counterclockwise. Don't force anything. Didn't I say that already? ;-)
See: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Final Reassembly. The nuts and washers substitute for the Bayonet Mount and associated parts prior to their installation. The photos show the lens in the Locked position.
The right photo in Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Final Reassembly shows its appearance now.
That's it! With care, match marks, photos, attention to detail, perseverance, and a bit of luck, the entire disassembly and reassembly process was not impossible and a learning experience. Now the lens should work perfectly if it did originally or if broken parts were replaced. If the lens survived and you survived, the next one will be easier. After the 17th iteration, it will seem totally trivial. ;-)
While the details for other lenses will differ, the general procedures will have a lot in common and doing this first with a lens like the AF-S DX 18-55mm VR II should provide good experience before tackling a larger expensive one. The key to success is understanding how the motion of the lens clusters is "programmed" by the tracks inside the Fixed Barrel and then being able to install them correctly during reassembly.
Most of the photos are now present in the Web Album. Except for the first 2 stock photos, all are of lens #6 except for the few showing the back of the lens with the bayonet mount and associated parts removed.
Other than the front of the 7th lens group and back of the 6th lens group which has some mottling (which was easily removed with 90% isopropyl alcohol), the interior including the PCBs, connectors, SWM, gears, and everything appear to be pristine with no evidence that contamination caused the lens's failure. So perhaps it was zapped by static. And yes I violated my recommendattion to not remove the 7th,8th lens groups but there is really no intention to put this lens back in service.
Some conclusions so far: The VR II is somewhat cost reduced but in a good way. ;-) For example, only one wire needs to be unsoldered to totally disassemble it to the level of major components. Most flex cables plug into the CPU PCB (PCB1) and are the push-in type with locking levers to break. Many have a small hole near the end of the cable for a thin instrument to aid in removal. There is a minimal number of pieces of double sticky tape or adhesive which would need to be replaced if reassembled.
Focus implementation is generally similar to that of the AF-S VR lens but the SWM gear train is part of the main structure and NOT a separate assembly. The tachometer and its gears are gone. Speed sensing has been implemented with a magnetic strip as in some other AF-S lenses. The good news is that the SWM itself and the two remaining gears are replaceable without major disassembly.
The focus encoder coding is of course different than the one in the AF-S VR and all other lenses I've checked. But is that a surprise? ;-) See Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Focus Encoder Coding. This encoder has 6 data bits with 22 states. The spacing almost makes sense being fairly similar in the central region and further apart near the ends. The extra tracks in the photo are pass-through for the magnetic read head.
The Zoom Encoder does NOT run axially as in the the AF-P 18-55mm VR lens (which has a similar lock button). It runs around the perimeter of the inner surface of the Fixed Shell and is extended to cover the locked area with a constant code. (Take care not to damage the brushes if the Fixed Shell needs to be reomoved.) At the location where it becomes unlocked, there is a very small length where the common conductor extends to the next one over, but that would not result in a different code, so its purpose is mystery. See Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Zoom Encoder Coding. This encoder has 8 data bits with 36 active states and the locked state. In the main portion of the active zoom region, their spacing is similar but not precisely the same. For the locked region, the code is a constant 00110001. Note the 8 data bits rather than 6 data bits for all the other lenses analyzed so far. Yet again, we have a change to the encoder coding and now even the number of bits for no fathomable reason. 6 bits would be plenty. It almost seems as though the designers of these lenses (1) are not privy to documentation on other lenses, (2) have a serious case of NDITD (Not Developed In This Department) syndrome, (3) never heard of lookup tables, (4) are smoke'n sump'n, or (5) all of the above. It makes no sense whatsoever.
The VR II VR assembly has changed slightly compared to the AF-S VR (I) lens. It is smaller and similar (but not identical) to the one in the AF-P VR lens. As with that one, the Hall sensors are gone so changes in the VR lens group position must be sensed in some other way.
The state of affairs as depicted in the Web Album is about as far as I intend to go in the disassembly. There are still a few individual parts that have not be removed or reduced to their individual pieces, usually due to issues of reversibility of the procedures, but all key sub-assemblies have been removed and documented. This applies for example to the SWM and VR assembly. There is little point to taking them to bits as that has been done for the 18-55mm AF-S VR and AF-P VR lenses, and they are similar. While nothing had been damaged, restoring the lens to its original condition is probably not going to happen. While there is a small probability that simply reseating the connectors will have cured the "not recognized by the camera syndrome", I'm probably not that determined to find out. And if the CPU PCB (PCB1) is dead, swapping in one from another lens will not work well as VR parameters and other settings need to be optimized for each specific lens using the custom specialized Nikon test instruments and software. However, physically putting it back together seems possible without having mastered a 27 level Rubik's Cube though there are a couple of steps that could be dicey like replacing the Fixed Shell.
Explanations of the dissection photos will be forthcoming so stay tuned. ;-)
(Some or most of these may not agree with how Nikon sees it as no internal diagrams or parts lists are available.)
And should anyone actually read this before the warranty on the Universe expires and has specific questions or requests, I may be contacted via the Sci.Electronics.Repair FAQ Email Links Page.
The trim ring is held in place only with a strip of ~1/4 inch tape wrapped around the entire lens. But while the original AF-S VR lens has a decent width area around its entire perimeter for the tape, the AF-S VR II trim ring only has six very narrow tabs that after awhile (or from an impact) can come loose as was the case with the first AF-S VR II lens I acquired (ID #1). See Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens with Loose Trim Ring. It looked really bad and the lens was destined for dissection if repair was not practical. But fixing it simply required removing the rubber grip by lifting it away from the body pulling it off, and then replacing the tape. But Nikon must use tape with super-strong adhesive as ordinary tape probably won't hold for long. So far though it's been behaving with just some Kapton tape, and many of the photos for the camera dissections have been shot using this lens. It might also be possible to use a few dabs of adhesive like 5 Minute Epoxy or industrial strength rubber cement between the trim ring and the barrel it seats against, but this has not be attempted - yet.
And the racing stripe (which is purely cosmetic) is just a length of really thin metal-coated tape which often detaches at one end. Or corrode as in the case of the lens ID #6 used for the dissection. It can usually just be peeled off if desired, which is a lot easier than attempting to neatly glue it back in place.
This procedure may apply to some other Nikon lenses. But specifically NOT to the similar AF-P lens where removing the CPU contact block screws results in the individual contacts popping out all over the place. ;-(
A #00 or #000 Philips screwdriver is required for the 3 sizes/types of teeny screws:
See Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Bayonet Parts.
CAUTION: DO NOT attempt to rotate the Zoom Barrel with these screws removed as the whole thing can come apart requiring an order of magnitude greater level of skill to reassemble. Specifically, the Fixed Shell may come free of the Fixed Barrel taking the SWM Gear with it and possibly damaging the Zoom Brush as well as the Focus Assembly and Zoom Barrel popping out the front.
Individual parts of the bayonet mount can now be replaced if necessary, though this will at least one level up of fiddlyness. ;-)
Reassemble in reverse order. And don't force anything! All of these are tiny screws so stripping holes is possible. When reinstalling the bayonet mount, carefully insert the aperture tang straight into the plastic receptacle that moves the iris diaphrapm. Unless the bayonet mount is replaced without changes, the setting of the aperture tang may need to be adjusted. It's secured with 2 screws and sealer. I do not know what the official procedure is, but in lieu of that, make sure the aperture tab (that's activated by the camera) just touches the the edge of the cutaway in the inner ring. Then after securing the bayonet mount, confirm that the tab moves smoothly by hand and the aperture goes through its entire range.
This lens (Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II ID #4) works perfectly in all respects from its closest focus to around 2 feet. It will go back and forth between those distances all day without issues. But beyond there, it will never move the focus ring to get closer, and at some point it will jam against the end-stop beyond infinity.
This is a works in progress but here are some observations:
My current hypothesis is that the encoder that reads focus position is either not working correctly or has perhaps become disconnected. So the lens's microbrain is getting confused, poor thing. ;( ;-) Among other things it's not being programmed to provide the necessary torque to focus in from near infinity, and it's overshooting infinity, hitting the end-stop and getting really stuck there. Monitoring of the SWM waveform appears to show that it is trying but almost certainly attempting to rotate the focus ring in the wrong direction. With the high gear ratio, it should have no problem backing away. The only way to unstick it if jammed is to flip the A/M switch back and forth. However, even if not jammed, it will still not focus in from more than around 3 feet to infinity. It will focus reliably from the closest spec'd distance to around 2 feet, though it may overshoot dramatically but doesn't jam. All these lenses sometimes overshoot especially if there little detail in the focus zone.
Since there is a definite boundary beyond where it screws up, this would appear to rule out an SWM or gear train problem. The SWM rotor and all gears except the one on the focus ring itself go through multiple revolutions over the focus range. The rotor of the SWM itself goes through ~2.75 revolutions for each revolution of the focus ring drive gear and that goes through nearly 2 complete revolutions to move the focus ring from end-to-end.
So this is probably a control problem. The only inputs to the microbrain are the tachometer (a magnetic strip with read head) and the focus encoder (which senses the absolute position of the focus ring). It's possible the magnetic pattern the tachometer uses has been partially erased, but the most likely cause is the focus encoder: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens Focus Encoder Coding with the bits color coded and labeled with the binary value at each position. More on these encoders can be found in the section: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens. But interestingly, the focus encoder in the Nikon AF-S DX Nikkor 18-70mm f/3.5-4.5G ED IF Zoom Lens also has 4 conductive strips and 6 bits, but the coding differs, which really doesn't make any sense unless each new Nikon designer is required to change something as a test. ;-)
If you're not totally confused, you weren't paying attention. ;-) But to reiterate: It is most likely that the focus encoder is either feeding bad readings to the microcomputer or they are being misinterpreted.
No doubt disassembly of this lens will be required at some point, to satisfy my curiosity if nothing else. Hopefully the problem will be something obvious like a damaged focus encoder brush, loose connector, or some dirt or soda residue on the encoder strip. ;-) However, based on the dissections (See above), this requires fairly significant surgery, so it may be postponed until Major Medical insurance coverage is available. ;-(
If it fractured at its base, the original shaft can be reused but if it fractured in the middle, a substitute shaft will be required which can be made of metal. Note that the original shaft is NOT a constant diameter but is thinner at the top. It is not known whether this is essential if a replacement shaft is used. It probably allows for a larger tolerance in the positioning of the metal fork of the Autofocus A/M switch.
Either way, a hole will need to be drilled perfectly centered and square in the Fixed Barrel so that a replacement shaft can be installed. The diameter at the base is approximately 0.045 inches but this should be confirmed. Ideally it will be a press-fit without requiring adhesive.
The AF-P lens is optically very similar to the AF-S versions, above, but with one additional lens element. However, it uses the Nikon so-called "Pulse" technology (thus the "P" in AF-P) for autofocus instead of the "Silent Wave Motor" (SWM, or S in AF-S). Pulse autofocus is based on a stepper motor and does indeed appear to be quieter than silent. ;-) While SWM uses a piezo motor driven at an ultrasonic frequency (above human hearing) which in itself should be very quiet, the motor's rotating surface plate in contact with the actual PZT element, associated gear train, and other rotating parts makes detectable noise.
So AF-P lenses return to motor technology with magnets and coils. ;-) As noted above, the "P" is supposed to stand for "Pulse", which kind of applies. They are claimed to be even quieter than AF-S lenses and that is probably true. The manufacturing cost is also much lower. ;-) And there have been comments on various forums about AF-S autofocus reliability, which is quite credible given their complexity and opportunities for contamination to get to the motor. So perhaps a little of both. Replacing the piezo motor with a stepper motor also allows the AF-P lens to be more compact since the motor itself is less bulky and the high voltage drive components and gear train are eliminated.
However, AF-P lenses are not compatible with the D5100 or D3200 (or earlier) cameras that are happy with AF-S lenses. Others like the D5200 may need a firmware upgrade (but that is a free download). And since there is no VR switch on the AF-P lens, VR is always enabled on these cameras since there is no electrical contact in the camera body to control it. (The AF-P version has 8 contacts compared to 7 on the AF-S.) But this incompatibility is almost certainly due to a business decision for planned obsolescence. There would not appear to be any reason why an AF-P lens could not have been designed to look like an AF-S lens as far the the autofocus commands are concerned. Or at worst, with a way of selecting the mode via a switch
The AF-P lens is also significantly narrower than the AF-S VR lens and very slightly narrower than the AF-S VR II lens which could be in part due to the more compact drive setup. The piezo motor has a relatively large diameter (almost 1/2 inch) and the gear train also takes up space. For smaller lenses like these, the only option is to increase its overall diameter. The stepper motor with its direct worm drive can greatly reduce the required space.
The AF-P lens destined for analysis is definitely well worn. The lock button doesn't work properly and in addition, one of the three tabs on the bayonet mount is broken off. Nonetheless, it still seemed to work well enough on a camera. But from the start, its days were numbered. ;-)
After starting the dissection, I had other suggestions for the "P" in AF-P: "Pathetic" or perhaps "Plastic". Nearly everything structural is made of plastic except the screws, some specer rings/shims, and a few tiny brackets. The sleeve/barrel that "programs" the motion of the lens groups based on the zoom setting is a polished anodized aluminum cylinder with precision milled slots in the AF-S VR lens (and most likely the ED lenses that came before it). But it is made of plastic in the AF-P lens, though this change actually occurred with the AF-S VR II lens.
However, having said that, the AF-P lens is much simpler and may be more reliable than its AF-S cousin. Autofocus has only two moving parts - a stepper motor with worm gear shaft which moves an internal lens group over a total distance of around 7 mm using low voltage drive. Compare that to reduction gears in the AF-S lenses along with the possibly tempermental ultrasonic piezo motor. The manual focus ring generates signals to the microbrain that then controls the same motor - it is not directly coupled to it: "Focus by Wire". Vibration Reduction (VR) is simplified as well with no Hall-effect sensors or lock mechanism. As a result, the electronics are also much less complex. In fact, as will be seen below, the electronics is perhaps an order of magnitude simpler in terms of the number parts compared to the AF-S version. This may be largely due to the lack of need for the high voltage piezo drive since the large ferrite inductors or transformers and drive components are eliminated. But may also be due in part to the higher level of integration available at the time of its design. And there are no critical surfaces to get contaminated as with the ultrasonic piezo motor. So I officiatlly retract "Pathetic" because the AF-P lens should be functionally at least as capable as the AF-S version, and more reliable without the SWM, high voltage drive, and gear train.
But it almost appears as though this particular lens must be assembled from the inside-out. :( ;-) For example, in order to get to access any internal parts, the curved strip with contacts that make connections to the camera body must be disassembled down to its individual contacts, which then pop out all over the place. It isn't self contained with the flex-cable as in the AF-S. So if the plastic bayonet mount gets damaged (as would seem to be quite common even though this is a small light-weight lens), replacing it requires some serious manual dexterity. Nikon must have saved 3 cents. ;-)
Taking it to bits non-destructively isn't that bad, though putting it back together without detailed instructions would be like solving a 10-level Rubik's Cube blindfolded. ;-) But that may be resolved soon.
One mystery is solved though with respect to the silent propulsion system for autofocus. As expected and noted above, there is a very small stepper motor (~3/8" diameter) whose shaft has an integral worm gear and no other gears. That rests in a Nylon U-shaped bushing enabling the entire focus assembly with the 3rd lens group to be moved back and forth by around 7 mm with an opto-interrupter as a limit sensor at one end. The focus ring works in parallel with the manual focus electronically: There is an incremental encoder consisting of spokes on the perimeter of the focus ring with a pair of nearly microscopic opto-interrupters in quadrature to sense their movement. So, the stepper motor can be driven either by the autofocus electronics or focus ring essentially at the same time. It's "Focus by Wire". ;-) But manual focus will not work if power is off, which is only of academic interest unless the lens is used in an incompatible camera or for another application. This is fundametally unlike the AF-S version of this lens where the focus ring actually moves a lens group on a helical track and the A/M focus switch selects (1) whether it is coupled to the gear train and (2) lets the microbrain know.
Without a gear train, this should be quieter than the AF-S. The stepper motor itself may make a detectable sound but sliding noise will reduced and there is no gear train to whine. But as a practical matter, the noise level of neither of these lenses is objectionable and only of relevance for some very specific applications where a "Do Not Disturb" sign is present. ;-)
Nikon AF-P DX Nikkor 18-55mm f/3.5-5.6G VR Optics
The AF-P has 6 lens groups (unlike the AF-S that has only 4), though some may be single lens elements.
The position of the 1st and 2nd-6th (in the same relative position) lens groups move independently depending on zoom setting. The position of the 3rd changes relative to the others depending on focus setting controlled by the stepper motor.
Most of the photos referenced below are also available as a Web Album (though possibly at slightly lower resolution) at Nikon AF-P DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Parts Web Album.
An absolute encoder for focus is not needed since the stepper motor is digitally precise: The position of the 3rd lens group for focus is proportional to the number of steps and direction referenced to a limit sensor at startup. The focus ring at the front of the lens is incremental and does not control the focus setting directly.
Here is a summary of the Nikkor 18-55mm AF-P DX f/3.5-5.6G VR lenses I've acquired so far:
Finding a certifiably broken (defines as non-functional) AF-P lens has been a challenge. Sometimes it's a case of the seller testing using an incompatible camera or not realizing the lens won't be recognized if locked. I usually attempt to inform sellers of these possibilities. Really. I haven't gone so far as to ask for a refund because the lens works though. ;-) As can be seen, the lock doesn't lock on most of these. Can you say "poor design"? ;-) There is a plastic ridge on the inside of the zoom barrel and gets damaged if attempting to rotate it without pressing the lock button. Or something. So that doesn't qualify as "broken". :)
If how to get at the cable isn't self evident, remove the curved contract shell (1 screw) which will release the flex cable from the rear outer shell. But the 8 ball contacts will pop out - don't lose any. The cable can then be unplugged after the next step. This may be necessary to be able to plug the cable back in during reassembly, so if that is your objective, might as well do it now.
Remove the 3 screws securing the 6th lens group and set it aside along with the screws and washers.
The VR assembly is much simpler than on the AF-S lens. The Hall-effect position sensors are gone as is the lock mechanism. Three really tiny springs as well as two blobs of some elastomer goop hold the lens element more-or-less centered regardless of orientation. There are only two coils and their associated pairs of rare earth magnets, each with U-shaped pole pieces.
With no lock to restrict the movement of the VR lens, when VR is OFF (on cameras that support that), the only ways of minimizing movement are to effectively short out the coils which will reduce movement due to eddy currents or for the VR system to drive the coils with appropriate anti-VR waveforms to effectively lock it in place. None of these would be available on cameras without an electronic VR-OFF setting. Or perhaps that elastomer goop serves a similar purpose. ;-)
That's basically it. There are now a pile of parts where there used to be an AF-P lens. ;-)
I have been able to reassemble it into a mechanically correct configuration, though that was a challenge. While it's reasonably straightforward to get the major pieces screwed into their proper place, fitting them into the appropriate combination of grooves and slots in the cylinders that control how far each one moves as a function of zoom is a challenge. There are probably match-marks in conjunction with jigs that to the trained (Nikon) eye would make this intuitively obvious. The parts now move in what appears to be the correct way based on zoom, but that was through random chance. There are 3 separate assemblies that move based on zoom that need to go into their respective grooves and slots, and also need to be correctly oriented with respect to the quasi-3-fold symmetry of the lens, so among other things, the zoom distance labels, and mark and lock line up correctly. This will become more straightforward with experience, but certainly is a challenge the first time.
And having been successful with the AF-S VF II, I am optimistic that this one will yield to enough determination.
The more I look at these, the more they appear to be marvels of engineering down to the casting/molding of the numerous circuitous groves, slots, holes, posts, blocks, and other structures in plastic. It's probably just Zoom Lens Design 101 but still impressive to the uninitiated. ;-) Unfortunately, sometimes they aren't strong enough as will be seen with the 18-70mm lens, below. :(
Gener- (1) Auto- Focus Focus Manual Year Model ation Optics Focus Encoder Tachometer Focus Introduced -------------------------------------------------------------------------------- AF-S ED 1 2C/9G/13E SWM Yes Magnetic Mechanical 2005? AF-S VR 1.5 2C/11G/15E SWM Yes Magnetic Mechanical 2007? AF-S VR II 2 2C/9G/13E SWM Yes Magnetic Mechanical 2007?
A montage showing stock photos of all known versions of the 55-200mm lenses as of 2022 may be seen at: Nikon AF-S DX 55-200mm f/4.0-5.6 Zoom Lenses. These are from Nikon lens product or review pages (copyright © Nikon Corporation) scaled so the relative sizes are close to correct.
What's remarkable is how much larger the VR version is compared to the others. And then with the VRII it seems they decided "never mind". ;-)
More to come.
This is a basic lens without VR.
I have had 2 of these:
I am currently evaluating how well swapping of the 1st Lens Groups on these lenses work without adjustments. There are the normal shims between the lens group and focus ring whose main purpose is to fine-tune the position of the 1st Lens Group so the lens can focus correctly at infinity. But #1 also had a pair of half shims on one side apparently to tilt the lens group slightly. It's not clear if that is a lens group issue, or lens focus ring or body issue. Can you say "kludge"? ;-) Considering how much free play there is in all these plastic lenses, it's not clear how much that would help. But perhaps #1 was a particularly bad specimen.
With the label removed, a pair of holes for a spanner wrench will be visible, which is probably what Nikon uses since they have plenty of labels. ;-) Using a spanner is less stressful on the lens than #2 below. And it has the benefit that the label can be replaced in the original orientation. While the label would line up correctly if replacing it in the lens but not if swapping them between lenses. (A pair of tiny depressions for a spanner could also be drilled through the label 180 degrees apart no more than 1 mm or so in depth in locations avoiding the printing. The label would not need to be rmeoved and the cosemtic damage would be minimal.)
This approach is also shown in Nikkor 55-200 : Haze and fungus removal - YouTube, though his lens appears to have been previously repaired.
Once the 1st Lens Group is free, keep track of the shims. Should there be a partial shim or shims, it or they are probably stuck in place with some sort of adhesive and remain there unless the 1st Lens Group is being swapped with one from another lens or vice-versa. In that case, you're on your own. ;( ;-)
Reassemble so it is just snug.
However, accessing them isn't too involved.
Just don't get over zealous in removing the 2nd Lens Element as I did and chip the edge, which could impact photo quality at low f/ stops. At the very least, it's ugly. ;(
I have four samples of this lens:
At first I assumed that the SWM itself was gummed up and unable to move. But the problem turned out to be that one of phases of the SWM drive signal was not present. Phase A (arbitrary designation) was nice and strong at around 240 V p-p but Phase B was dead. This was determined with the use of my 55-200mm VR SWM Test Rig, which does away with the Fixed Shell and brings out the two SWM drive phase signals and ground soldered to conveniently located pads on the SWM flex cable. So these and others can be probed in situ while on a camera. See the dissection photos for the actual contraption, as well as what the phase signals look like. There was also something strange about this lens as the grounding wire to the spring contact was disconnected at the contact-end and the insulation over most of its length was missing and the conductors were frazzled looking like a horses tail. ;-( It was replaced with the light gray wire in the photo. Whether that was the cause or result of the bad SWM drive - or a total coinidence - is not known. Testing the SMT transistors marked K1YSD next to the ferrite components with a DMM reveals that there is a short across a pair of leads for the lower one. According to an SMD marking code database, these are Samsung KSA3265-Y SOT-23 NPN transistors: 30 V, 800 mA, 200 mW, which would sounds about right EXCEPT that this is on the OUTPUT side of the transformer which can have more than 200 V on it! So perhaps it isn't a KSA3265-Y. Since I don't believe in coincidences, I wonder if the stray ground wire shorted to something and blew the transistor. But assuming the part number is correct, the Fairchild/ON Semi KSC3265 appears to be an acceptable substitute. Now to justify a Digikey order for a 26 cent part. ;-)
As it turned out, the apparently shorted transistor was a red herring. It turns out that these are not bipolar transistors but MOSFETs based on the Nikon patents. And stray voltage on the gate was fooling the multimeter into thinking there was a short. When that was discharged, the SO23 parts on both POW PCBs behaved the same.
But swapping the POW PCB made no difference. One phase was still dead. The next step was to check the SWM. The dead phase was an almost dead short at the SWM. But swapping the SWM also made no difference. As a last resort, the CPU PCB was swapped and three was the charm. ;-) With the good SWM, original POW PCB, and swapped CPU PCB, the lens sprang to life. Autofocus now works. About those coincidences, it's possible I blew the original CPU PCB because the cable between it and the POW PCB was installed slightly angled and perhaps making improper contact when the POW PCB was first swapped. That causing the same problem is unlikely but if not, one must accept that both the SWM and CPU PCB were bad. VR doesn't appear to activate though even with the VR switch ON. Oh well, can't have everything.
With the brain transplant, any parameters stored in its memory that were optimized for the lens from which the CPU PCB originated are now incorrect. How much difference that may make is yet to be determined.
This is now my "Visible" lens with its innards exposed. ;-) Even if it can be repaired, it may never be destined to be buttoned up. Having a partially naked lens could prove handy. ;-)
An attempt was made to locate the short but it provded to be very well disguised even after complete disassembly of the SWM and under high magnification. So when subtlety doesn't work, try brute force: Discharging a capacitor across the "short" cleared it But nothing exploded, so its location is still a mystery. The SWM may get tested eventually. It was disassembled for the photo shoot, cleaned, and put back together.
In fact, the cause turned out to be a crack in the Fixed Shell with a small piece hitting a spring pressure strip and getting stuck. Repair of a small plastic piece is not realistic so it was removed along with the metal strip, whose function appears to be to add some resistance so zoom doesn't move so easily that the lens changes the zoom setting on its own. However, with that done the lens appears to work just fine, thank you. Exactly how that Fixed Shell cracked is not at all clear. There is no sign of trauma to the lens. The Fixed Shell minus the offending piece is shown in the dissection. It is at the upper right of the Fixed_Shell_Front1 photo.
AF and VR seem OK now.
Initial finding on ID #3 is that the zoom value returned by the Zoom Encoder was incorrect beyond around 100 mm - 105 mm read back as 100 mm, 135 mm read back as 100 mm, and 200 mm read back as 145 mm. These data were determined from the EXIF data for a series of test shots. One common cause is contamination on the encoder strip. Unfortunately (or fortunately) depending on one's point of view, this appears to have corrected itself temporarily at least. Perhaps the contamination was rubbed off. This may be wishful thinking but for the time being it works so don't fix it. ;-)
However, AF works well but VR doesn't seem to activate.
At this point, everything that is simple to get at on the back of the lens is exposed.
More to come.
Reassemble in reverse order. The most fiddly part of reassembly (after making sure the shipm stay in place) is probably reattaching the ground wire. If soldering back to the pad on the flex cable, cover the edges of the Switch Bay with Kapton tape or something similar to protect the plastic from accidental contact with the soldering iron tip. The wire was cut, stip the ends and solder them together, finally insulating with Kapton tape, plastic electrical tape, or a glob of 5 minute Epoxy. Coming someday.
More coming soon.
This is a rather nice relatively compact light weight lens. It looks somewhat like an AF-S DX 18-55mm VR II lens on steroids and only very slightly larger than the 55-200mm ED version, both of which are shorter than the VR version.
Since neither of these is really broken, the search is on for a third speciment for dissection and to repair ID #2.
Nikon AF-S DX Nikkor 55-200mm f/4.0-5.6G VR II Zoom Lens Photos and Description
The 55-200mm VR II lens is the most compact of the three which makes it much more desirable than the VR version. It uses the typical SWM and gear train but with a drive frequency of around 290 kHz based on measurements using a sense coil and scope. It also has the dither pulses continue for a few seconds after focusing like some of the other AF-S lenses.
Nikon AF-S DX Nikkor 55-200mm f/4.0-5.6G VR II Zoom Lens Photos and Description
The start of a dissection is available at Nikon AF-S DX Nikkor 55-200mm f/4.0-5.6G VR II Zoom Lens Dissection Web Album. But only stock photos, dimensions, a partial optical architecture diagram, and external photos.
More coming soon.
Autofocus on this lens is quick, but not necessarily quieter than on the AF-S lenses using the small motor and gears. The motor and lens has sliding surfaces which still make some sound.
But the sacrificial victim (ID #2) makes abnormally loud grinding noises and fails to be able to focus correctly - either manual or auto. :( ;-)
The cause became obvious as a huge part - the entire 2nd lens group - was loose inside the lens not attached to anything just bouncing around. ;-( Figuring that the 1st lens group would detach like the others - by unscrewing it after removing the label, that was attempted first. But either it has left hand threads or it is really tight and I don't have the needed spanner wrench, so it remains securely attached. No matter. ;-)
Plan B was to go in from the back, where the action is in any event. This turns out to be quite simple and even reversible. Removing several screws around the side of the bayonet mount and the back allows both to be removed without damaging anything. The electronics PCB is then exposed and its cables can be unplugged easily along with the Focus A/M switch revealing the full diameter autofocus Silent Wave Ring Motor. The contacts remain safely inside their housing.
Nikon AF-S DX Nikkor 18-70mm f/3.5-4.5G ED IF Zoom Lens Photos and Description
Most of the photos referenced below are also available as a Web Album (though possibly at slightly lower resolution) at Nikon AF-S DX Nikkor 18-70mm f/3.5-4.5G ED IF Zoom Lens Parts Web Album.
Being simpler than the VR lenses, there are fewer photos for this one, but there is always the on-line repair manual to refer to:
According to the repair manual, alignment will be required if the 4th or 5th lens groups are removed. So, avoid doing this if possible. Or, at least, as each of the 3 screws is removed, take a closeup of the exact relationship of the screw hole to the clearance hole.
Prior to disassembly, the piezo motor did work well when focusing, moving from one end to other in 1/10th of a second or less. However, due to the broken tab on the 2nd lens group cell, it didn't do anything useful. :(
That gray spot where the flex cable center conductor attaches to the PZT stator ring (left-most piece in the left photo) almost looks burnt. But it's just a bit of conductive adhesive to assure good contact. There is a small hole in the flex-cable underneath it.
The rotor (right-hand pieces in each of the photos) consists of 4 parts: The aluminum ring with a lip which is what's in contact with the stator, a thin steel ring next to it, a segmented aluminum ring next to that, and the black plastic shell molded around everything, The sliding surface of the rotor is an insulator, possibly an aluminum oxide coating, and there is also no electrical contact between the metal rings embedded in the plastic shell or to the rotor itself.
To check the drive signal, a 3 turn coil was wrapped around the working AF-S 18-70mm lens. Not surprisingly, its frequency is much lower than for the small motor in the AF-S 18-55mm lens, clocking in at only around 28 kHz. The frequency is still ultrasonic, but not by that much. ;-) And as noted with respect to the AF-S 18-55mm lens, above, this would be a good way of determining if autofocus failure is due to lack of drive or a mechanical problem. But the sensed amplitude is lower, at around 20 mV p-p since the source is more buried. Use more turns if desired. ;-)
This lens appears to be more repair-friendly than the ones above especially if there is no need to go inside the assembly with the 7th-13th lens groups. There should be no need to unsolder any wires and the flex cables detach easily. As noted above, just keep track of everything with photos, notes, and added match marks.
However, note that there is a magnetic strip and magnetic pickup that provides a signal in place of the tachometer in some lenses that have the small SWM with gear train. Not only is it delicate and damaged easily, but ferrous tools can cause the magnetic pattern to become corrupted, which needless to say, would not be good. Even accidentally touching the strip with a slightly magnetic screw drive could potentially erase it.
And if you're curious as to how the focus is controllable mechanically both via the Focus Ring and Ultrasonic Piezo SW Ring Motor at the same time, it's similar in concept to a differential gear box but with no gears. Focus is actually controlled by a ring with a metal fork that engages the plastic tab on the middle lens cluster. That is mounted on ball bearings as shown in the photo above. On the front-side is a plastic ring that is in contact with the ball bearings that engages with the rubber/plastic manual Focus Ring. On the back side is the rotor of the PRM which is in contact with the opposite sides of the ball bearings. The friction of the focus fork ring is quite low (or should be) so when the ball bearings are rotated by either the Focus Ring or Piezo motor rotor, it moves at 1/2 the rate of either but does not (or at least should not) affect the other ring. However, where the lubrication had gummed up or there is damage from abuse. This appears to be a common problem with the AF-S DX 18-200mm f/1:3.5-5.6G VR and VR II lenses (below) where focus fails to work properly over part of the Zoom range or at all.
There are no immediate plans for a detailed dissection but for now see the Nikon AF-S DX Nikkor 18-70mm f/3.5-4.5G ED IF Zoom Lens Dissection Web Album. There is no dissection yet but it shows some stock photos and the optical architecture and how the lens groups move with zoom.
While in principle, it would probably have been better to simply swap the focus lens group into the original lens, other parts may have been damaged in the initial discombobulation.
And that's how it will remain!
I purchased 4 of these to date described as "For Parts or Repair". All are in very good to excellent physical condition with little evidence of wear and no abuse. All exhibited similar problems except for ID #1:
ID #4 (SN: US2576365): Generally good cosmetic condition but focus may get stuck over part of its range though it works most of the time, similar to ID #1. VR seems dead.
VR appears to be non-functional on all of them unless I'm missing something to enable it. Yes, I've exercised both the VR ON/OFF and VR Active/Normal switches. Unfortunately, without removing the Bayonet Mount and related parts, the switches cannot be testee as they are part of the Fixed Shell. Other VR lenses work fine on the D70 including the VR II version of this lens.
All of these had a hint of hessitent manual focus at least until exercised a bit but now work fine. This would appear to be a common problem with the 18-200 VR and VR II lenses with their physically long zoom extension. Apparently so is broken VR unless I've been extremely unlucky...... ID #1 is currently at the top of the list for dissection but it may only go deep enough to confirm there isn't a simple fix for the noisly and non-functional VR in which case the VR actuator flex cable will be unplugged to quiet it down. ;( ;-).
There is no dissection yet, but see the Nikon AF-S DX Nikkor 18-200mm f/3.5-5.6G VR Zoom Lens Dissection Web Album. There is no dissection yet but it shows some stock photos, the dimensions, optical architecture, how the lens groups move with zoom, and a detailed drawing of the internal structure.
These photos were taken using one of my trusty D70s with the AF-S 18-55mm ED lens that had a damaged Filter Ring. See: Repairing Broken Focus Tabs on Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G ED Zoom Lens.
I do have one in mint condition and another that is cosmetically nearly as good but does not always focus reliably, even in manual mode. But there are no current plans for a detailed dissection of either, or even to investigate this lens in greater detail unless someone would like to donate a sacrificial specimen for analysis. The asking prices on eBay are way above may curiosity quotient for a lens to take apart and likely never put back together so it functions. ;-) Appropriate chants and incantations will be issued to the gods of dead camera lenses upon request but it will not likely survive the experience. :( ;-)
However, eventually the one with the unreliable focus may end up being used for this purpose.
But see the Nikon AF-S DX Nikkor 18-200mm f/3.5-5.6G VR II Zoom Lens Dissection Web Album. There is no dissection yet but it shows some stock photos, dimensionas, optical architecture, how the lens groups move with zoom, and the detailed internal structure of the VR version (which should be very similar). A dissection of that lens is likely to happen sooner and is expected to be virtually identical.
These photos were taken using one of my trusty D70s with the AF-S 18-55mm ED lens that had a damaged Filter Ring. See: Repairing Broken Focus Tabs on Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G ED Zoom Lens.
I have not found a repair manual or even an exploded diagram for this lens, though it appears to be generally similar to the 18-200mm VR and 28-300mm VR versions for which there are manuals. If anyone has one for this lens, please contact me via the Sci.Electronics.Repair FAQ Email Links Page.
I purchased a certifiably broken sample and it was used for my photos below. But not inside yet. The main issue is that VR does not do anything. That could be as simple as a bad switch or wire that came off. This is a well used lens but focus (A and M) works and while zoom is a bit hard to move at times, nothing appears really damaged, though there is a serious nick in the lens hood mount ring (visible in some of the photos) so it has experienced some trauma.
See the Nikon AF-S DX Nikkor 18-300mm f/3.5-6.3G VR Zoom Lens Dissection Web Album.
This lens does take photos as long as one is careful to avoid camera shake, so reducing it to parts may not happen for a while. But the back was opened to check for obvious problems. The flex cables were all secure and the VR switch was tested so an easy fix is unlikely. However, if removing the bayonet and related parts, make sure to record the precise location of the brass shims - which I of course neglected to do initially. This lens has 2 and they are not identical so the orientation and also which one is on top may matter, though it's not clear why. And when reinstalling the aperture tang, take care that it goes into the correct location in the aperture actuator. Unlike many other lenses, it's a rectangular hole on this one, not just cup or U-shaped lever. It can slip in outside the hole and while it may appear to work when first installed, when the Inner Ring is put in place, it will jam. Other than that, reassembly is quite straightforward. There are only 4 types of screws and where they go should be intuitively obvious. ;-) But some are quite small so losing them is too easy and would be bad. ;-( And don't overtighten them!
As they say: "If it ain't broke, don't fix it.". After going inside, two things changed: First, the image through the viewfinder "jerks" initially when the camera is turned on and the shutter is pressed, but only when VR is on. However, VR doesn't do anything else. This indicates that VR is being powered but is jamming to one side. I don't think VR did anything when first testing the lens. So perhaps that's an improvement. ;-) Second, autofocus stopped working reliably. I could have sworn it wasn't like that initially. Sometimes it would lock but usually it would either get stuck at one end of its range, or continue hunting back and forth around the optimal focus unless very close, in which case it might lock. So the back parts were removed again and it was discovered that one of the brushes in the Focus Encoder wasn't contacting the encoder strip. I have no idea how that could have occurred during the excursion inside as it's safely recessed. But once the brush was "adjusted", autofocus is back in shape. The microbrain had no idea where focus was at any give time so it didn't know what to do. Poor thing. ;-)
I also reseated all the internal flex cables at the same time as dealing with the focus issue but that didn't make any positive difference to VR.
However, now the lens produces 4-1/2 "clunks" about 1/2 second apart when the camera is powered up and sometimes when it's powered down regardless of whether VR is on, independent of zoom and focus settings, but only with autofocus enabled. They sound like they are coming from the vicinity of the VR assembly but don't appear to do anything to the image in the viewfinder. The count of 4 is digitally precise and the behavior is totally repeatable. Go figure.
Having said all that, the lens takes great photos and therefore I have no plans to go inside again. If only it could be filled with helium so to weigh less. And the previous version was even heavier so I'm searching for a sample. ;-)
Stay tuned just in case.
Modern lenses are much more sophisticated and no one would want to go back to the fully manual older ones, but silky-smooth operation is not one of their features. And it's easy to see why. Most of the moving parts are made of plastic and a zoom lens has many of them. For example, see Major Moving Parts of Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens. These all move when changing zoom or focus. The three cylinders at the top of the photo reside nested and rotate or slide with respect to each-other with a large surface area in direct contact. The center one is made of anodized aluminum with precisely milled slots that determine the required movement of multiple lens groups with respect to each-other when zoom is adjusted; the other cylinders are formed or molded plastic. The straight slots in the upper-left (outer) cylinder guide those moving parts that must not rotate. Pegs or rollers (without ball bearings) restrict their movement to the AND of the slots in the upper left and the other cylinders, but also add friction. Some parts reverse direction as the Zoom Barrel is turned, adding additional friction/resistance at that point. It's all rather intricate and I bet Nikon has a really nifty CAD package for zoom lens mechanical design. ;-)
As an example of a common much larger lens, see the diagrams in Nikon AF-S DX Nikkor 18-200mm f/3.5-5.6G VR Zoom Lens showing Lens Group Positions at 18 and 200 mm. Lens Group 3 and the VR assembly move together, but those and all the others move relative to one-another and relative to the lens structure attached to the Nikon F mount.
Even on a brand new lens, there is detectable roughness and varying resistance over some parts of the zoom range. Over time, the lens will be exposed to dust, moisture, and contamination either from normal use or from being tossed in a storage bag, it gets worse as there are no real seals. And plastic is subject to wear. The good news is that for the most part, none of this makes any real difference in picture taking performance. That is, until the thing seizes up completely or falls apart. :( ;-)
But if the lens is dropped or whacked, parts like those pegs can get broken off or may dig into the tracks with varying degrees of damage. In minor cases, the roughness will just become worse but with enough trauma, major functions will stop working. When considering the purchase of a used lens, carefully check autofocus, manual focus, and vibration reduction, as well as for correct operation of the aperture at all zoom settings. Don't accept a lens where manual focus doesn't work reliably even with a discount (as I once did) because the seller said no one ever uses it. While that may be partially true, unreliable manual focus can be a symptom of more major problems. One thing that is often broken on used lenses though is the Lock button if there is one, used to secure the lens in a compact state for storage. The internal lip that the button engages is made of plastic and users often attempt to twist the Zoom Barrel without realizing it's locked, so that lip gets damaged and the button non longer works properly. That alone is probably not sufficient reason for rejecting a lens - but perhaps it may be leverage to negotiate a discount! While Lock may not work or work well, the end-stops for the Zoom Barrel should not be affected. But this should be confirmed as bad things may happen on some lenses if the Zoom Barrel is rotated beyond the normal range.
See the Web Album at: Copal Square S Focal Plane Shutter Mechanism. (The Web Album photos are scaled to fit within 1024x768 pixels but the full size originals have the name under the thumbnail with a ".jpg" added.) The first 4 photos are of a beat up Nikkormat FTN in various stages of disassembly starting with most of the pieces of the lens mount in place to revealing the Copal Square S shutter in situ. These are followed by closeups of another similar shutter. The primary difference between them is the use of a less expensive Nylon gear for the speed select compared to the highly polished brass one, and some slotted head screws in place of Philips head screws. Since there is no real stress on that gear, cheaper is just fine, thank you. ;-) My black dot on the white gear lines up with the post for the 1 second setting. In the interest of full disclosure, I have swapped the gear and screws to make the separate shutter mechanism more photogenic. And in the interest of expediency, the screws that secure the body parts have been left off. ;-)
Two manuals relating to Copal Square S Shutter repair are known to be available on the Web and hard copies may be purchased on eBay and elsewhere. Both Copal Square S Shutter Repair Manual and Copal Square S Shutter Repair Guide are interesting reads, but they may not enable you to be able to do much in the way of repair. The first one does have a 75 (!!) step procedure with diagrams for assembling a shutter. ;-) Aside from the intricate nature of these mechanisms, special jigs and instruments are required for some of the procedures. However, cleaning and lubrication of specific parts may be possible. This will involve the use of solvents like alcohol or naptha along with an ultrasonic cleaner if available, followed by lubricating specific bearing points and surfaces ONLY with the tiniest speck of special oil or grease as appropriate. A shotgun approach of simply sprayng it with degreaser and adding oil anywhere that looks appropriate will likely result in a nice paperweight. DO NOT even think about allowing WD40 or anything similar near a precision mechanical device like this! ;( ;-) A Web search will turn up suitable procedures but take them all with a grain of sand.
Control of the shutter bears similarity to that of mechanical leaf shutters, but it needs to determine the timing of the pair of blinds rather than opening and closing a set of leaves. For the Copal Square S There are three (3) regimes of timing:
And as a matter of interest, operation of the shutter in a fully mechanical SLR and specifically the Nikkormat is as follows:
For the "B" setting, everything is the same except that a tab on the shutter linkage prevents the shutter from closing until the button is released. The actual shutter speed is probably forced to 1/1000th second so closing would not be delayed no matter how quickly the button is released. The Nikkormat doesn't have a "T" setting, but for that operation would be similar but there would be a simple escapement that would require the button to be pressed a second time to close the shutter.
It turns out that a variety of types of glass and plastic may be used and the optical elements may be either ground and polished or molded. Sometimes the lens specifications will include some information on the material thought probably NOT the fabrication method if the Marketing Department thinks it will help sales. For example, Extremely low Dispersion Glass (ED Glass) and aspheric are pointed out in the info for lenses like the AF-S DX Nikkor 18-55mm or 18-200mm. They probably won't state anything if plastic. ;-) If not specified, the material can be any either common optical glass (BK7, crown, flint, etc.) or plastic. Aspheric elements are probably molded since individually grinding and polishing them would be cost prohibitive.
There is no easy way to determine the material and fabrication method non-destructively (or at least without some damage) on an intact lens as they appear identical. But even if the lens is disassembled into the individual lens groups it's a challenge. Glass is several times more dense than plastic so the weight of a lens group can be a tip-off, especially for the larger ones. Ground and polished lenses will generally have frosted edges while molded ones will have smooth lips and perhaps even tabs. But the overall appearance of the individual lens elements is essentially identical in terms of surface finish and AR-coating.
Some possible causes are:
Diagnostics: Test with another AF-S lens. If that also fails, the camera is likely at fault.
All cameras tested that would turn on worked correctly with AF-S lenses. Dead cameras don't count. ;-)
Diagnostics: Cycling the switch back and forth a few times may clear any contamination. But on lenses with the small SWM, this also engages and disengages the gear train, so that can result in the gears moving a bit with respect to each other and avoiding a damaged tooth or becoming unjammed. Set the switch to M and confirm that the focus ring moves smoothly by hand. Also confirm that there is normal free play in the focus ring with the switch set to A. This should be a few degrees of rotation or around a mm at the perimeter. It should not be tight with no free play. Then listen carefully for any sound while the camera is attempting to focus. If present, there may be a mechanical problem in the gear train. If there is none, then it's an SWM or electronics problem.
Diagnostics: In a quiet room, listen for mechanical noise when the lens should be focusing. If the SWM is seized, there would likely be none as the drive frequency is beyond the range of human hearing - typically between 25 kHz and 300 kHz, though it might be audible to your pet bat. ;-) If you can hear anything which sounds similar to the sound made during normal focusing but the focus ring isn't moving, a mechanical problem is likely.
See the info above on lens ID #4.
Diagnostics: Cycle the A/M switch and move the focus ring. Determine if there is focus distance or range of distances where autofocus works consistently. and if there is a preference for focusing in or out.
On one Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II zoom lens (my ID #4), AF was intermittent and just cycling the A/M switch sometimes helped. But rotating the focus ring with it set at M always seemed to allow the lens to focus correctly for several shots. There was no binding or detectable resistance so this suggests a damaged gear. When it stopped working, repeating this would get it to recover. Since the gear ratio is so high and the motor and immediate drive gears are disengaged with the A/M switch set to M, the only gear likely to be relevant is the ring gear on the focus ring. The pinion gear that engages it goes though more than one revolution and all the others go through multiple revolutions over the focus range. And when rotating the focus ring manually, it also rotates the pinion gear. Chipped or damaged teeth would be detectable. Likely causes are damaged or dirty focus encoder or tachometer. For more info, see the section: Autofocus only Works Over Limited Range on Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II Zoom Lens.
Diagnostics: Test the discrete semiconductors near the ferrite components on the POW PCB for shorts. On one lens with these symptoms, two pins were indeed shorted on the SO23 drive transistor for one of the phases..
Diagnostics: If an oscilloscope is available - almost any type, even an antique - it's simple to check for the presence of drive signals, though determining if both are present might be challenging. All that's needed is a simple sense coil of a half dozen turns with a diameter of around 1.5 inches. The sensitivity with the typical AF-S lens is very roughly 10 mV p-p/turn. It doesn't have to be beautiful. ;-) Using a 10X probe but no other termination should be adequate. For all the lenses I've tested, a good place to position the coil is directly underneath the lens slightly near the camera. But feel free to experiment. ;-) With the scope's vertical sensitivity turned up, there should be a very distinct signal while the lens is attempting to focus, and for some cameras, possibly even after it had succeeded or given up. What is probably being detected up are the fringe magnetic fields from the ferrite components on the SWM driver PCB. A lack of this signal would probably indicate an electronics problem. See the sections on the specific AF-S lens models for details on testing. It's straightforward if fiddly to remove only the Fixed Shell on some of these lenses so that the innards can be probed while on a camera.
On one Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR zoom lens (my ID #1, the lens documented in the section: Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens), AF was totally inoperative and there was obvious damage stator and rotor of the SWM as can be seen in Nikon AF-S DX Nikkor 18-55mm f/3.5-5.6G VR Zoom Lens Autofocus Drive Assembly and Piezo Motor Parts.
On a lens that is otherwise functional and recognized by the camera, possibly not having been used in a long while, the stator may have stuck to the rotor of the SWM. If repeatedly attempting to focus does nothing and the switches, weak battery, and menu settings have been ruled out, it's possible the SWM is just lazy. The first test if technically savvy would be to check for the SWM drive signals using a coil of wire and oscilloscope as described elsewhere in this document. If strong drive signals are present, attempt to rotate the focus ring while autofocus is active. Don't go to excess as there is a risk of stripping gears, but some modest torque may free it up. If it does move but in either directly during focus, one of the high voltage drive phase signals may be missing. If it only moves in one direction, there may be contamination on the rotor-stator interface surfaces but both phases are probably present. If the focus ring cannot move at all, it is sometimes possible to access the SWM through the switch cover and prod the rotor with something pointy like a jeweler's flat blade screwdriver WITH THE CAMERA TURNED OFF taking extreme care not to touch anything but the edge of the rotor. If the rotor can be moved at all, autofocus may then work and should be exercised. Depending on the cause, this may be a permanent fix but the symptoms if there is significant contamination or damage. Use of a drop of cleaner/degreaser may help but don't use a spray as there could be permanent collateral damage. Just a drop on the interface between the stator and rotor and then exercise it. Else total stripdown of the SWM - or replacement - may be required.
This would most likely require disassembly and inspection of the encoder strip and brush assembly.
This would most likely require disassembly, inspection, and electrical testing.
Diagnostics: Similar to those for the SWM, above.
This has not been seen except where someone damaged a cable or lost parts of a lens. ;-)
Since there are no user seriveable parts inside ;-), this is probably only justified to attempt cleaning of a gummed up SWM, or for curiosity.
-- end V1.41 --