Notes on the Troubleshooting and Repair of Video Cassette Recorders


  4.6) Rental tape considerations

It would be nice for your VCR if rental movies had never been invented.
You have no idea of the history of any tape you bring home.  The following
may also apply to tapes in your video library or tapes given to you by
friends or relatives:

* The tape may be old and old tapes shed a lot more oxide and crud than
  newer tapes.  A single playing may clog your video heads.

* The tape may have been damaged by a prior viewing and one pass through may
  ruin your expensive video heads.  A tape that has been seriously crinkled
  due to a VCR tape eating incident and then wound back into the cassette
  may be a ticking time bomb for your VCR.  A tape with a partial break or one
  that has been improperly spliced is even more likely to cause serious
  damage.  Do not splice tapes - see the section: "Recovering damaged or broken tapes".

* The cassette mechanism itself may have been damaged (from being dropped
  or stored in a hot automobile) with unknown consequences for your VCR.

Note: if you should ever damage a rental tape as a result of a cranky VCR
or for any other reason, don't just give it back to the video store.  Please
let them know.  Also, if your VCR should jam with a tape inside, do not
forcibly extract it - read the appropriate sections later in this
document.  If in doubt, let the video store know what happened and
follow their recommendations.

Given that you are not likely to give up the movie couch potato addiction,
some problems can be avoided by fast forwarding a couple of minutes into
the tape before hitting PLAY.  Damage to rental tapes often occurs near the
start - and this will avoid some of the useless coming attractions as well!

If you notice the video breaking up or deteriorating while you are watching,
immediately ejecting the tape may be the most prudent option since the worst
may be yet to come!

While I cannot control your viewing habits, playing a lot of old, dirty,
deteriorated tapes (rental or from your own tape library) will eventually
take a toll on your VCR.  At the very least, you should perform a general
cleaning and inspection at more frequent intervals.

(From: Jim Lagerkvist (jlager@tir.com)).

Renting a video tape has all the same potential consequences as renting
a hooker.  That tape may pass to your machine anything from pizza grease
to splices made from duct tape or staples.  I keep two VCRs in my house.
One for rental tapes and another for known trusted tapes.

Chapter 5) VCR Maintenance and Troubleshooting Guide

  5.1) Safety

Once you remove the cover(s) of a VCR (ignoring the warnings about no user
serviceable parts, etc.), there are some risks to you and your VCR.
You also, of course, void the warranty (at least in principle).  Therefore,
if the unit is still under warranty, having it serviced professionally may
be your wisest option.

Stay away from the line side of the power supply - put electrical tape over
the exposed connections.  To be doubly sure, tape a piece of cardboard or
thick plastic over the power supply section.  Other than that, there is
more danger of damaging the VCR by accidentally shorting something out
or breaking a little plastic doodad than of you getting hurt.

* Don't wear any jewelry or other articles that could accidentally contact
  circuitry and conduct current, or get caught in moving parts (protect
  long hair as well).

* If circuit boards need to be removed from their mountings, put insulating
  material between the boards and anything they may short to.  Hold them in
  place with string or electrical tape.  Prop them up with insulation sticks -
  plastic or wood.

* Connect/disconnect any test leads with the equipment unpowered and
  unplugged. Use clip leads or solder temporary wires to reach cramped
  locations or difficult to access locations.

* If you must probe live, put electrical tape over all but the last 1/16"
  of the test probes to avoid the possibility of an accidental short which
  could cause damage to various components.  Clip the reference end of the
  meter or scope to the appropriate ground return.

* Perform as many tests as possible with power off and the equipment unplugged.
  For example, the semiconductors in the switching power supply of a VCR
  can be tested for shorts and the fusable resistors can be tested for opens.

* If you need to probe, solder, or otherwise touch circuits in a switching
  power supply with the power off, discharge (across) large power supply
  filter capacitors with a 2 W or greater 20-100K resistor and then verify
  with your voltmeter.

* The use of GFCI (Ground Fault Circuit Interrupter) protected outlet is a
  good idea but will not protect you from shock from many points in a line
  connected power supply.  A circuit breaker is too slow and insensitive to
  provide any protection for you or in many cases, your equipment.   A GFCI
  may prevent your scope probe ground from melting should you accidentally
  connect it to a live circuit, however.

* Don't attempt repair work when you are tired.  Not only will you be more
  careless, but your primary diagnostic tool - deductive reasoning - will
  not be operating at full capacity.

* Finally, never assume anything without checking it out for yourself!
  Don't take shortcuts!

  5.2) Troubleshooting tips

Many problems have simple solutions.  Don't immediately assume that
your problem is some combination of esoteric complex convoluted
failures.  For a VCR, it may just be a bad belt or an experiment in rock
placement by your 3-year old.  Try to remember that the problems with the
most catastrophic impact on operation (a VCR that eats tapes) usually
have the simplest solutions (replace the idler tire).  The kind of problems
we would like to avoid at all costs are the ones that are intermittent
or difficult to reproduce: the occasional interference or a VCR that 
sometimes will not record your favorite soaps on alternate Thursdays
before a full moon.

If you get stuck, sleep on it.  Sometimes, just letting the problem
bounce around in your head will lead to a different more successful
approach or solution.  Don't work when you are really tired - it is both
dangerous and mostly non-productive (or possibly destructive).

Whenever working on precision equipment, make copious notes and diagrams.
You will be eternally grateful when the time comes to reassemble the unit.
Most connectors are keyed against incorrect insertion or interchange
of cables, but not always.  Apparently identical screws may be of differing
lengths or have slightly different thread types.  Little parts may fit in
more than one place or orientation.  Etc.  Etc.

Pill bottles, film canisters, and plastic ice cube trays come in handy for
sorting and storing screws and other small parts after disassembly.

Select a work area which is well lighted and where dropped parts can
be located - not on a deep pile shag rug.  Something like a large plastic
tray with a slight lip may come in handy as it prevents small parts from
rolling off of the work table.  The best location will also be relatively
dust free and allow you to suspend your troubleshooting to eat or sleep or
think without having to pile everything into a cardboard box for storage.

Another consideration is ESD - Electro-Static Discharge.  The electronic
components in a VCR are vulnerable to ESD.  There is no need to go overboard
but taking reasonable precautions such as getting into the habit of touching
the chassis first before any of the electronic components is a good practice. 
The use of an antistatic wrist strap would be further insurance.

A basic set of precision hand tools will be all you need to disassemble
a VCR and perform most adjustments.  These do not need to be really
expensive but poor quality tools are worse than useless and can cause
damage.  Needed tools include a selection of Philips and straight blade
screwdrivers, needlenose pliers, wire cutters, tweezers, and dental picks.
A jeweler's screwdriver set is a must particularly if you are working on
a portable VCR or camcorder.  For adjustments, a miniature (1/16" blade)
screwdriver with a non-metallic tip is desirable both to prevent the
presence of metal from altering the electrical properties of the circuit
and to minimize the possibility of shorting something from accidental
contact with the circuitry.

You should not need any VCR specific tools with the possible exception of a
miniature metric hex key wrench set for loosening the set screws on the
roller guides should you need to perform a tape path alignment.  I have
never needed a VCR head puller.  You can make a tool for the special nut
found on many A/C head assemblies for tracking adjustment by filing a
slot in the blade of a straight blade screwdriver.

A low power fine tip soldering iron and fine rosin core solder will be
needed if you should need to disconnect any soldered wires (on purpose
or by accident) or replace soldered components.

See the document: "Troubleshooting and Repair of Consumer Electronics
Equipment" for additional info on soldering and rework techniques.

For thermal or warmup problems, a can of 'cold spray' or 'circuit chiller'
(they are the same) and a heat gun or blow dryer come in handy to identify
components whose characteristics may be drifting with temperature.  Using the
extension tube of the spray can or making a cardboard nozzle for the heat
gun can provide very precise control of which components you are affecting.

For info on useful chemicals, adhesives, and lubricants, see "Repair Briefs,
an Introduction" as well as other documents available at this site.

If you have several VCRs or do repairs for friends (former friends?),
there are inexpensive kits of VCR mechanical parts like washers and
springs that come in handy.  General belt or similar kits are not
worthwhile unless you are in the service business - there is too much
variety in the sizes and other characteristics of these types of parts
to make an assortment a good investment.

Note: while working with the top off, you may need to put pieces of
strategically located cardboard over the area of the cassette to block
extraneous light from causing erratic behavior (modes aborting, not
starting at all, etc.) with the start/end-of-tape sensors.  Not all VCRs
are sensitive to extraneous illumination but I have been bitten more than
once by  not doing this.  Using overhead instead of direct illumination
will probably help as well.  In extreme cases, placing electrical tape
over the end sensors may be needed but this will likely confuse the
microcontroller under certain conditions into thinking that a non-
existent tape is present - or if your troubleshooting will permit, leave
a cassette in the transport. (I have heard of at least one case where
this was a problem even for normal operation - apparently, light was
falling on the VCR in just the wrong way where it happened to be located.
The VCR would enter rewind mode regardless of what the helpless human
wanted unless tipped on end!)

  5.3) Test equipment

Don't start with the electronic test equipment, start with some analytical
thinking.  Many problems associated with consumer electronic equipment
do not require a schematic (though one may be useful).  The majority
of problems with VCRs are mechanical and can be dealt with using nothing
more than a good set of precision hand tools; some alcohol, degreaser,
contact cleaner, light oil and grease; and your powers of observation
(and a little experience).  Your built in senses and that stuff between
your ears represents the most important test equipment you have.

A DMM or VOM is necessary for checking of power supply voltages and
testing of sensors, LEDs, switches, and other small components.  Unless
you get deep into the electronic repair of VCRs, an oscilloscope is not

There are two items of important test equipment that you probably already

* A video signal source - both RF and baseband (RCA jacks).  Unless you
  are troubleshooting tuner or video/audio input problems, either one
  will suffice.  RF sources include a pair of rabbit ears or an outdoor
  antenna, a cable connection, or a VCR with a working RF modulator.
  Similarly, a working VCR makes a handy baseband or RF signal source.

* A display device.  A video monitor or TV makes an excellent video signal
  display.  Many video problems can be diagnosed by just examining the
  picture.  If you have an old TV with a vertical hold control, this is
  useful when adjusting backtension, should the need arise.  A B/W TV is
  adequate for many of the tests you will be performing.

  5.4) Why you should read the entire FAQ first

If you have no prior experience with precision electromechanical repair,
don't just jump in as the following actual experience demonstrates:

(From: someone who would prefer not to be identified).

"Ok, I did something dumb.  I was given an old VCR (early 80s) a couple 
weeks ago (JVC-7100U).  It stopped playing and recording, but FF and
rewind worked fine.  Reading the FAQ, I decided to check it out.  I took
the top off, and was trying to make the motor run so I could see the 
problem.  There was an incandescent light, and I figured there was
a light sensor, so I moved the lamp out of the way.  The FAQ suggests
electrical tape over the lamp, but I hadn't read it yet.  My manipulation
caused the lamp to fail.  Until I could replace it, I just jumped the
connection, which worked fine for awhile.  I had just figured out the
problem with play/record was a drive wheel not making contact with
the take-up reel.  It seemed to be a result of a weak spring, and I
was trying to figure out which one, when the screwdriver I was 
manipulating the arm with  slipped, and contacted the back side of 
a circuit board.  Lesson number two:  Use a chopstick for that purpose.
I believe it was at this point I realized I got no reaction from
any of the VCR control buttons, so maybe I shorted something out.  All
the buttons worked before.  Even worse, as I was reinstalling the
tape loading mechanism, the screwdriver slipped again, in a different
place, and I did see a flash when it contacted the back of the circuit
board.  Whoops."

Don't let this happen to you.  Or, at least start out with an old expendable
VCR and accept the hits to your pride!

  5.5) Cassette cheaters

When troubleshooting mechanical problems in a VCR, one of the handiest
accessories is a cassette cheater - a frame to fool the VCR into thinking
there is a cassette in place so that you have access to the reel spindles
and idler.

You can buy these for $6-12 but you can make one that is almost as nice:

* Take a discarded cassette, open it up and throw away everything but the top
  and bottom halves and the screws.

* Punch out the plastic windows - and somewhat more of the top and bottom if
  you are so inclined - relatively little of the original structure is
  actually needed to fool the microbrain of the VCR!  The more open the
  cheater is, the easier it will be to see and access guts of the VCR while

* Reassemble the two halves of the cassette with the screws (you did save the
  screws, right?).

* Put a bit of black tape over the sensor holes on the sides of the cassette
  (near where the hinge pins of the flap went).

These cheaters will load and 'play' just fine except that some machines
actually sense that the supply reel is being turned by the tape movement
during loading or always and will shut down if it isn't (among other
peculiarities) so you may have to do this by hand.

There are several benefits to using one of these, one of which is that
there is no chance of ruining a prized tape due to a hungry VCR.  You will
also be able to feel the spindles to get an idea whether they are turning
properly and with enough torque in all modes.  If you break out enough of
the top and bottom, you will have access to the idler and other under-cassette
parts at the same time.  If you examine one of the commercial cassette
cheaters, you will see that very little is needed beyond the outer frame as
long as it sits properly on the indexing posts and doesn't jam the mechanism
when loading/ejecting.

  5.6) Test tapes

When aligning the tape path, a test tape will be needed as a reference.
Actually, you want two - one recorded at the SP (2 hour) speed and another
recorded at the EP (6 hour) speed.  These do not need to be exorbitantly
priced professional alignment tapes.  A couple of recordings made on
a known working VCR will get you close enough for most purposes.
Do not use these same tapes for diagnosing or testing of mechanical problems,
your VCR may be hungry and they may get eaten.

For general video diagnosis including mechanical and tape eating problems,
a bunch of sacrificial tapes is handy - advertising, promos, feature shorts -
anything you do not care about but have been recorded on working VCRs.
Very often they get mangled and you do not want to continue to use mangled
tapes which may damage the VCR - in particular the video heads.  However, once 
you have the VCR basically working, you will want to test it start to finish
on a T120 cassette.  This is because the reel hub size on those short
video cassettes is not the same as a standard (most commonly used) T120
cassette and may mask problems if the VCR is mechanically marginal in some

  5.7) Getting inside a VCR

You will void the warranty - at least in principle.  There are usually no
warranty seals on a VCR so unless you cause visible damage or mangle the
screws, it is unlikely that this would be detected.  You need to decide.
A VCR still under warranty should probably be returned for warranty
service for any covered problems except those with the most obvious
and easy solutions.

It is usually very easy to remove the top and bottom covers on VCRs.
For the top cover, there are usually some very obvious screws on the back
or sides, and in rare cases on the top.  There may be a couple of screws
on the bottom as well that secure the top cover.  For top loaders, you
will probably need to remove the cassette holder lid - there will be two
screws, perhaps hidden by rubber plugs.

Once all the screws are out, the top cover will lift up or slide back
and then come off easily.  If it still does not want to budge, recheck
for screws you may have missed.

For the bottom cover, there are usually a half dozen or so screws around its
perimeter and sometimes in the middle as well.  There may be one or two
grounding screws as well which are of different length and threads - these
should go back in the same location from where they came.  Bottom covers
are usually simple sheet metal.  In rare cases, you will need to remove
the front panel to free the bottom cover (or vice-versa).

Circuit boards may prevent access to the top or bottom of the tape
transport.  Usually, removal of a few screws (often marked with red
paint or arrows on the circuit board) and perhaps pressing of a couple of
snaps will permit the board to be swung up on a hinge out of the way.

Front panels usually snap off, possibly requiring the removal of a few
screws on top or bottom.

Make notes of screw location and type and store the screws away in
a pill bottle, film canister, or ice cube tray.

When reassembling the equipment make sure to route cables and other wiring
such that they will not get pinched or snagged and possibly broken or have
their insulation nicked or pierced and that they will not get caught in
moving parts.  Replace any cable ties that were cut or removed during
disassembly and add additional ones of your own if needed.  Some electrical
tape may sometimes come in handy to provide insulation insurance as well.

  5.8) Why does my VCR shut down or behave strangely when I remove the cover?

There are various sensors in a VCR that are light sensitive - it is not
a safety interlock (though it acts this way in some VCRs) but a result
of the way the tape start and end sensors operate.  VHS tapes
have a clear leader and trailer.  An LED or light bulb poking up near
the center of the cassette shine towards sensors at either side of the
cassette.  When light is detected the VCR assumes that it is at the
appropriate end of the tape and shuts off (or rewinds if in PLAY mode
when it senses the end depending on model).

During servicing, a piece of opaque cardboard or other insulating material
should be placed above the cassette basket if any strange behavior is
detected that was not present with the cover in place.  Not all VCRs are
particularly sensitive external illumination.

  5.9) Getting built up dust and dirt out of a VCR

This should be the first step in any inspection and cleaning procedure.

Do not be tempted to use compressed air!

I would quicker use a soft brush to carefully dust off the circuit boards and
power supply.  Work in such a way that the resulting dust does not fall on
the mechanical parts.

For the deck itself, using compressed air could dislodge dirt and dust which
may then settle on lubricated parts contaminating them.  High pressure air
could move oil or grease from where it is to where it should not be.  If you
are talking about a shop air line, the pressure may be much much too high
and there may be contaminants as well.

A Q-tip (cotton swab) moistened with politically correct alcohol can be used
to remove dust and dirt from various surfaces of the deck (in addition to
the normal proper cleaning procedures for the guides, rollers, heads,
wheels, belts, etc.)

  5.10) What to do if a tiny tiny part falls into the VCR

We have all done this: a tiny washer or spring pops off and disappears from
sight inside the guts of the unit.  Don't panic.  First - unplug the VCR if it
is plugged into the AC.  Remove the battery pack from a camcorder.

Try to locate the part with a bright light without moving the VCR.  You may
have gotten lucky (yeah, right).  Next, over an area where a dropped part
will be visible (not a shag carpet!), try any reasonable means to shake
it loose - upside down, a little gently tapping and shaking, etc.  A hard
surface is better in some ways as you might hear the part drop.  On the
other hand it may bounce into the great beyond.

If this does not work, you have two options:

1. Assume that the part has landed in a place that will not cause future
   problems.  There could be electrical problems if it is metallic and shorts
   out some circuitry or there could be mechanical problems if it jams some
   part of the mechanism.  There is an excellent chance that the part will
   never cause any harm.  What chance?  I don't know, maybe 99%.  It is not
   worth taking the unit to pieces to locate the part.  You are more likely
   to damage something else in the process.  Obtain a replacement and get on
   with your life.  The exception is, of course, if you now begin experiencing
   problems you **know** were not there before.

2. Take the unit to pieces in an attempt to locate the part.  For all you
   know, it may be clear across the room and you will never find it inside.
   If all the gymnastics have not knocked it loose, then it may be really
   wedged somewhere and will stay there - forever.  If the VCR behaves
   normally, then in all likelihood it will continue to do so.

To prevent this sort of thing from happening in the future you will no doubt
be much more careful.  Sure you will!  Some suggestions to prevent ejection
of an E-clip, split washer, or spring into the great beyond:

* Construct a paper dam around the area.

* Tie a thread or fine wire around the part before attempting to remove it.
  Keep this 'safety line' on until after it has been reinstalled, then just
  pull it free.

* Keep one finger on the part as you attempt to pop it free.

* Hold onto the part with a pair of needlenose pliers or tweezers while prying
  with a small screwdriver.

Chapter 6) VCR Tape Transport Fundamentals

  6.1) Parts of the tape transport in a VCR

Thanks to Brian Siler (bsiler@PROMUS.com) for using his Snappy(tm) rig to
capture the original photos.

Please refer to the photo: Typical VHS VCR Tape Transport Components for parts

The following description applies to 99.9% of the VCRs in existence today.
I have seen one that had a sideways loading mechanism - very weird.

Looking at the unit from above with the front toward you:

* Supply spindle - left hand side platform on which the supply tape reel
  (inside the cassette) sits.  The edge which contacts the idler tire, and
  associated brake pad, should be cleaned.

* Takeup spindle - right hand side platform on which the takeup tape reel
  (inside the cassette) sits.  The edge which contacts the idler tire, and
  associated brake pad, should be cleaned.

* Idler - assembly which swings between supply and takeup reels and transfers
  power to the appropriate reel to wind the tape up during play and record
  and often to drive FF and REW.  This may use a rubber tire or a gear.

* Idler tire - the black rubber ring on the outside of one part of the idler
  which actually contacts the reel edges.  This is single most likely part
  to need replacement after a few years of use.  Some VCRs use a gear instead
  of a tire, but the tire is most common, especially in older units.  Clean
  and inspect - replace if in doubt.  See VCR with Idler Tire for a typical
  tire-type idler assembly.

  Some VCRs use gears in place of rubber (as is the case with the VCR shown in
  the photo: Typical VHS VCR Tape Transport Components.  Teeth can break off
  but these are generally quite reliable.  Some high-end decks may have
  separate motors for reel rotation.

* Roller guides - there are two, one on each side.  These assemblies move
  from their retracted position toward front of machine to their loaded
  position for play and record.  The white rollers should spin freely and
  be clean.  When retracted, the roller guide assemblies will be slightly
  loose.  However, when the tape is wound around the video head drum, they
  must be snug against the V-Stoppers - the brackets at the end of the tracks.

  Also on the same assembly are tilted metal guide posts - again
  one for each side.  These sometimes fall out with obvious consequences.
  Proper functioning and adjustment of the roller guides is the most critical
  requirement for proper tracking.  (However, do not touch their settings
  without being really sure that they are at fault and not until you have
  read the sections relating to tape path alignment.)  Clean and inspect.

* Roller guide tracks - combination of plastic and metal slots in which the
  roller guide assemblies slide during tape loading and unloading.  Check
  to make sure there is still some healthy grease on the surfaces.  If gummed
  up or excessively dirty, clean and relube with a dab of plastic-safe grease
  on each sliding surface.

* Video head drum or upper cylinder - approximately 2.45 inches in diameter
  by .75 inches high.  This rotating assembly contains the video heads (and
  HiFi audio and flying erase heads, if present).  Stay away from this unit.
  as video heads are very delicate.  If you must clean it, refer to the
  specific instructions on cleaning video heads elsewhere in this document.
  Video heads do not normally require cleaning despite what the cleaning tape
  people will have you believe.  If you are not having video noise problems,
  they should be left alone.

* Capstan - right side after tape exits from roller guide.  The capstan is
  a shaft about 3/16" diameter which during play and record (and search) modes
  control tape movement forward or reverse when the pinch roller is pressed
  against it.  Should be cleaned thoroughly to assure proper tape movement
  during play, record, and search modes.

* Pinch roller - black rubber roller about 1/2" diameter, 3/4" high which spins
  freely and is pressed against the capstan during play, record, and search
  modes.  It is constructed as a molded rubber sleeve fused to a metal roller
  on a small ball bearing.

  A hard, shiny, dried out pinch roller can lead to tape edge munching and
  erratic sound, speed, and tracking.  Clean thoroughly.  Inspect for cracked,
  hard, shiny, or otherwise deteriorated rubber and free and smooth rotation.

  Even if you have no obvious record or playback symptoms, if the pinch roller
  appears concave or with a distinct worn ridge, replacement is recommended -
  erratic behavior will soon be the result.  A tape which runs off center due
  to a bad pinch roller may result in tape edge damage and over time can also
  alter the wear pattern of the audio/control head and various guide posts.

* Audio/control Head Stack - between right roller guide (when tape is loaded
  around drum) and capstan.  Includes magnetic heads for non-HiFi (linear)
  audio and synchronization control track.  Should be cleaned since tracking
  and non-HiFi audio performance is critically dependent on its performance.

* Back tension arm - left side just as tape exits cassette - this is coupled to
  a felt Back Tension Band and serves to maintain a constant tension on the
  tape during play, record, and forward search.  Retracts toward cassette when
  tape is unloaded.  Back tension is somewhat critical and may need adjustment
  after long use.

* Various other fixed guide posts - vertical stationary metal posts which tape
  contacts.  Should be cleaned but rarely need adjustment.  The positions of
  these vary somewhat by manufacturer.

* Full erase head - left side towards rear which tape passes over just
  before going around roller guide, guide post, and drum.  Rarely causes
  problems.  Clean.

* Impedance roller - left side near full erase head.  Freely rotating roller
  stabilizes tape movement.  Some VCRs lack this component.  Clean.

* Half loading arm - right side near capstan/pinch roller.  On VCRs with
  'rapid or instant access transports' this helps to position the tape in
  the intermediate (half loaded) position.  A similar arm is usually present
  in other VCRs and helps to position the tape around the pinch roller.
  Check for free movement.  Clean.  Lubricate bearing if sluggish.

* Belts - various size black rubber bands - a typical VCR will have between
  0 and 12 of these on top and bottom.  Typical is 3 or 4.  Most are of square
  cross section though an occasional belt may be flat or round.  The belts will
  need replacement after a few years.  Clean and inspect.  Replace any belts
  that are hard, cracked, stretched, or flabby.  A good belt will feel soft
  and rubbery without cracks or other signs of deterioration.  It will return
  to its relaxed length instantly if stretched by hand about 25%.  Belt kits
  are generally available by VCR model but individual belts can be ordered as
  well.  In either case, this is very low cost maintenance which can make an
  absolutely huge difference in the happiness of your VCR.  New belts can often
  restore a comatose VCR to perfect health.

For additional information on replacement rubber parts, see the section:
"Determining belt, tire, and pinch roller specifications".

  6.2) Alex's quick tips

(From Alex (ramjam@globalserve.net)):

1. To confirm that a worn idler tire is causing a malfunction, without
   disassembly, I use a product called "Rubber Renue" (M.G.Chemicals Ltd.
   13-80 Hale Road, Brampton, ON L6W 3M1 Canada 416 454-4178). First I
   clean the tire with isopropyl alcohol (99%) then using the other end
   of the Q-tip I apply Rubber Renue. You don't need much, I have had the
   same 100 ml (3.4 oz.) bottle for over 6 years. What the product does is
   rejuvenates and conditions the rubber (read: makes *sticky*) as to
   allow normal or near normal operation. I don't recommend this as a
   permanent fix, though it can be, it is a great diagnostic tool and the
   whole procedure takes about five minutes.

2. To fix squeaky pulley shafts and collars I use a pipe cleaner (most
   smoke shops sell them) to clean the collars, I then use transmission
   fluid (the same stuff you put in your car) as a lubricant on the
   shaft. It's lightweight, it doesn't gum up, it's cheap and can be
   bought just about anywhere. Just remember not to use too much as it
   spreads easily, which can be disastrous in a VCR.  

  6.3) Most common problems

* VCR refuses to FF or REW and shuts off.
* VCR shuts off entering PLAY or REC or at random during PLAY or REC.
* VCR eats tapes.
* VCR doesn't accept tapes or ejects them without cause.
* Sound is wavery, fluctuating, or muddy.

The cause for all of these is very often a bad idler tire or other dirty,
worn, or tired rubber parts.  See the section below: "General guide to VCR cleaning and rubber parts replacement".  A VCR that just munched down your
favorite tape is very likely only in need of a little tender loving care.

WARNING: Don't turn a simple repair into a full length double feature.  Most
tires and belts come off without extensive disassembly.  However, if your VCR
is the exception, DO NOT remove anything to get at the rubber part that may be
part of a critical timing relationship - racks or gears, for example - before
fully understanding the implications of this action.  In some cases, if a gear
is rotated even one tooth from where it should be, there can be unforeseen and
catastrophic consequences.  See the section: "Mechanical relationships in VCRs" for more information before proceeding any further!

  6.4) General guide to VCR cleaning and rubber parts replacement

All the guideposts, wheels, and rubber parts of a VCR should be cleaned
periodically - how often depends on usage.  Of course, no one really does it
unless something goes wrong.

Do not attempt to clean the video heads until you follow the proper
procedure given elsewhere in this document, you can break them - very
expensive lesson.  In most cases, they do not need attention anyhow.

Q-tips and alcohol (91% medicinal is ok, pure isopropyl is better. Avoid
rubbing alcohol especially if it contains any additives) can be used
everywhere except the video heads.  Just dry quickly to avoid leaving
residue behind or damaging the rubber parts further.

Cleaning may get your machine going well enough to get by until any replacement
rubber parts arrive and to confirm your diagnosis.

Things to clean:

1. Capstan and pinch roller.  These collect a lot of crud mostly oxide which
   flakes off of (old rental) tapes.  Use as many Q-tips (wet but not dripping
   with alcohol) as necessary to remove all foreign matter from the capstan
   (the shiny shaft that pulls the tape through the VCR for play and record).
   Just don't get impatient and use something sharp - the crud  will come off
   with the Q-tips and maybe some help from a fingernail.

   Clean the pinch roller (presses against the capstan in Play, Record, and
   Search mode CUE and REVIEW) and until no more black stuff comes off.  Use
   as many Q-tips as necessary until no more black gunk collects on Q-tip.

   If the pinch roller is still hard, shiny or cracked, it will probably need
   replacement.  Many are available for about $6 from the sources listed
   at the end of this document.  It is sometimes possible to put the pinch
   roller in an electric drill, drill press, or lathe, and carefully file off
   the hard shiny dried out rubber surface layer, but only use a last
   resort - and this fix is probably temporary at best.

2. Various guideposts including the roller guides (the white rollers on metal
   posts which are near the video head drum when in play or record mode).
   When in FF or REW, or with no tape present, these move on tracks to
   a position toward the front of the VCR.  Note that the roller guides
   with the white rollers and tilted metal posts will be fairly loose
   when in the unloaded position (but you should not be able to lift them
   off the tracks).  When actually playing or recording a tape, they will
   be snug against the stoppers at the end of the tracks.

3. Idler tire (idler swings between reels and transfers motor power to
   reels - clean until no more black stuff comes off.  A dirty or worn idler
   tire is probably the single most common VCR problem.

   If the idler tire appears cracked, glazed, or dried out, it will need to be
   replaced.  About $.50-$1.00.  As a temporary measure, you can usually
   turn the tire inside-out and replace it.  The protected inner (now outer)
   surface will grip well enough to restore functionality until a replacement
   tire arrives - and verify the diagnosis as to the cause of your problem.

   Also, the idler assembly includes a slip clutch.  If this weakens, the
   idler may not have enough force to press on the reel table edges.  If it
   becomes too tight, there may be audio, video, or crickled tape problems
   and/or excess wear of the idler tire.  When in doubt, the entire idler
   assembly is often available as a replacement part.  They can often be
   disassembled and adjusted if necessary.

4. Reel table edges - surface on the reel tables where the idler contacts.

5. Audio/control head (right side) and full erase head, (left side).  Q-tips
   and alcohol are ok for these.

6. Anything else that the tape contacts on its exciting journey through your

7. Rubber belts.  Access to some of these will probably require the removal
   of the bottom cover.  After noting where each belt goes, remove them
   individually (if possible) and clean with alcohol and Q-tips or lint free
   cloth.  Dry quickly to avoid degrading the rubber from contact with the
   alcohol.  If a belt is trapped by some assembly and not easy to remove,
   use the Q-tip on the belt and/or pulley in place.  However, if it is
   stretched, flabby, or damaged, you will need to figure out how to free it.

   Make sure that there are no twists when a square cut belt or replacement
   is installed on its pulleys.

   On some models, you may need to unscrew circuit board(s) blocking access
   to either the top or bottom of the tape transport.  Make notes of what
   went where - particularly different types of screws and routing of wires.

   Any belts that appear loose, flabby or do not return instantly to
   their relaxed size when stretched by 25% or so will need to be replaced
   and may be the cause of your problems.  Belts cost about $.30-$2.00
   and complete replacement belt kits are often available by model for $3.-$12.
   Meanwhile, the belts will function better once they are cleaned, maybe
   just enough to get by until your replacements arrive.

8. Video heads: READ CAREFULLY.  Improper cleaning can ruin the expensive
   video heads.  DO NOT attempt to clean the video heads without reading
   and following the procedure described in the section: "Video head cleaning technique".

   While VCRs should be cleaned periodically, the video heads themselves
   usually do not need cleaning unless you have been playing old or defective
   rental tapes which may leave oxide deposits on the tips of the delicate
   ferrite head chips.  Unless you are experiencing video snow, intermittent
   color, or loss of or intermittent HiFi sound (HiFi VCRs only, the HiFi
   heads are located on the video head drum and for the purposes of cleaning,
   treated the same way) leave the video heads alone.

   If you really feel that video head cleaning is needed, refer to the
   sections on video head problem diagnosis and cleaning elsewhere in
   this document.

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Written by Samuel M. Goldwasser. | [mailto]. The most recent version is available on the WWW server http://www.repairfaq.org/ [Copyright] [Disclaimer]