Approaches to Using Fixed Frequency or Non-Standard Monitors on PCs
Copyright (c) 1994, 1995, 1996, 1997, 1998
All Rights Reserved
Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied:
I have absolutely no affiliation with any hardware, software, or service company with a vested interest in advocating one solution over another. The purpose of this document is to provide unbiased information to aid in making an informed decision. Contributions from non-commerical sources are welcome.
So, you have got the deal of a lifetime - a brand spanking new (or at least low mileage) high resolution 21" computer monitor that came from a DEC Alpha Workstation - or a Sun or HP - or Macintosh. Or, perhaps an IBM9517 which you were told has a super sharp bright picture. The cost to you: $1 or you haul it away. Is this really and truly a good deal if you use a PC? Questions like this come up all the time on comp.sys.ibm.pc.hardware.video. These are either fixed frequency monitors or incompatible with the common VGA/SVGA 'standards' in some other ways. A fixed frequency monitor is designed to operate at a single scan rate which usually means a single resolution such as 1280x1024. (Strictly speaking, the horizontal resolution is determined by the number of pixels sent on each scan line by the video card but this is a detail.) PCs running DOS, Windows 3.1, WFWG3.11, and Win95 generally require the monitor to run at multiple scan rates - one for each corresponding resolution. For example, boot at 640x400, VGA at 640x480, Windows at 1024x768 - and each one may have a correspondingly different horizontal and vertical scan rate. (Some workstation monitors are actually dual frequency but this does not really help since neither of the supported scan rates are what a PC wants.) Monitors likes the IBM9517 are not fixed frequency but are XGA compatible. This was an IBM abortion and not compatible with VGA/SVGA even for booting your PC. These types of monitors are generally manufactured by the best names in the industry such as Hitachi, Mitsubishi, Philips, Sony, etc. - and are thus often of very high quality. The specifications of these monitors may exceed those of any but the very top-of-the-line monitors used on PCs. The origianl cost of these monitors was probably much higher than an equivalently sized PC monitor as well. They become available as high performance workstations (whose technology advances nearly as quickly as that of PCs) are decommissioned or upgraded. The cost to you now is usually very low since they just take up space and you know how bean counters at big companies like to have all their beans lined up in a nice neat row :-) Some fixed freqeuncy monitors may be from Apple Macintosh computers as well. It would be nice if all you needed was a cable to use one of these beauties on a PC. Unfortunately, there is often much more involved in making these freebie monitors conveniently usable on a PC under DOS, Windows, or Win95. Note that some of these comments - a la scan rates - may not apply to systems like Linux if scan rate switching is not required. Note: just because a monitor has BNC connectors (or does not have a VGA/SVGA connector or cable) does not necessarily mean that is is a fixed frequency monitor and therefore a problem. Many top quality monitors only have BNC connectors and might be fully compatible with most video cards running PC/DOS/Winddows. The only way to be sure is to obtain the detailed video, sync, and scan rate specifications.
While workstation monitors look like PC monitors - they have a CRT and a power cord, after all - there are generally significant differences that prevent these from being a 'drop in' solution. The following are the principle difficulties in using a fixed frequency monitor on a PC: * Scan rates. PCs particularly with DOS/Windows/Win95 may require a number of different resolutions and scan rates during any work or play session. Workstations use one scan rate and resolution at all times including during boot. That is why the monitors are called fixed frequency. The video source must match the parameters of the monitor withing a few percent, not enough variance for typical PC applications. * Sync. PC VGA and SVGA video cards generate separate horizontal and vertical sync signals. Some may be programmable to generate what is known as composite sync. Workstation monitors may require composite sync or sync-on-green (this will be explained later). They rarely use separate H and V sync like a PC. Many PC video cards can only provide separate syncs. Some workstation monitors are already set up for various sync schemes but not all. * Video connectors. PCs nearly always have a miniature DB15 VGA/SVGA type connector. Workstation monitors may use separate BNC connectors (3, 4, or 5 depending on sync options), a 13W3 Sun style connector, or something totally non-standard. * Plug-and-play. The newest PCs and video cards expect to determine the capabilities of your monitor (to a greater or lesser extent) by either reading the monitor sense lines on the VGA connector or interrogating the ACCESS.bus. Neither of these will be present by default with a workstation monitor. The PC may come up in glorious black and white or refuse to operate in all modes.
A workstation runs at a fixed resolution and scan rate. All software is written to interface to the screen via a windowing system like X-Windows. PCs, on the other hand, must be able to drive a monitor at several quite different resolutions and scan rates: * DOS - 640 x 400 default boot screen. * DOS programs - 640 x 400 (EGA compatible), 640 x 480 (basic VGA), etc. (Note: CGA resolutions like 320x200 are emulated by modern video cards by running at 640x400 (for this example) and replicating pixels and lines.) * Windows/Win95 - 640x480, 800x600, 1024x768, 1280x1024, 1600x1200 etc. depending on your hardware and software. Normally, the highest resolution that the video card/monitor combination supports with good quality will be used most often. Some options like a larger desktop than the physical display with dynamic resolution switching require multiple scan rates, however. Therefore, a fixed frequency monitor driven from a typical video card (e.g., ATI GPT) has a problem. For a typical workstation monitor with a resolution of 1280x1024 operating at 78 KHz horizontal scan rate and 72 Hz vertical scan rate (fixed frequency), you only have one option - and that precludes the display of the DOS boot messages or running DOS applications or games. Note: for the remainder of this document, I use the term 'Windows' to refer to MS Windows 3.1, WFWG 3.11, and Win95 interchangeably. If all you run is Windows - never any DOS games or other applications that require you to suspend to a full screen DOS shell or run in native DOS mode - then you can always use a second VGA monitor for booting and then just switch over to the high resolution monitor once Windows comes up. Or, just assume your system **will** come up and forgo a display until the Windows desktop appears. Unfortunately, there are a lot of DOS applications still used so this not a solution for everyone. However, if you mostly use your PC for Autocad or Lotus, then this is a perfectly reasonable option if you have a suitable video card. (However, read on).
In order for the monitor to display a picture, it must know where the lines and frames begin. The synchronization signals - sync for short - are pulses sent for each line (horizontal sync) and each frame (vertical sync). There are 3 common schemes for doing this: 1. Separate horizontal and vertical sync signals. Individual wires are used for the H and V sync. This is the scheme that has been used for most PC video cards including MGA, EGA, VGA, and SVGA. It makes for easier hardware - particularly in the monitor. 2. Composite sync signal. The H and V syncs are logically combined (usually either OR or XOR) and sent on a single wire. This is used by Macintosh computers and Sun workstations, for example. Basically, it saves a wire. 3. Sync-on-green. The composite sync signal from (2) is combined with the green video signal (it actually goes on the bottom, from 0 to .3 V or so). The Red and Blue video signals usually do not have sync added to them but this is not always the case. Note that theoretically, (1) or (2) are best as there is no interaction between the digital sync signals and analog video signals but in practice, the difference is usually undetectable. The users manual for your monitor will identify which options the monitor supports. OK, so you don't have a users manual: For monitors with BNC connectors, it may be possible to determine capabilities by counting them: * 3 BNCs - Sync-on-green only (Red, Green+Sync, Blue). * 4 BNCs - Composite sync (R,G,B,CS) and possibly sync-on-green. * 5 BNCs - Separate syncs (R,G,B,HS,VS) and possibly composite or sync-on-green as well. Monitors with a 13W3 connector will generally accept composite sync though the other options may be possibilities as well. Some video cards (like the ATI GUP, GPT, and others) can be programmed in their SETUP or INSTALL program (or possibly from a command line option) to generate composite sync on the H or V sync wire. These will then work (at least with respect to sync) with a monitor requiring either separate or composite syncs. A few high-end cards can generate sync-on-green as well. Sync polarity (whether the pulses are negative or positive going) may be an issue depending on the design of the monitor. However, most suitable video cards can be programmed for either polarity. Therefore, depending on your video card, the sync issue may be a non-issue. Otherwise, an adapter will be needed. Unfortunately, this is not just a cable as circuitry is required to combine the signals. If you are electronically handy, it is a simple matter to construct a suitable circuit but if you are not, this may be a show-stopper unless you can locate a commercial product. Note that the term 'electronically handy' means a bit more than knowing how to read the resistor color code. The circuits are very simple. However, for the adapter to work well at the very high video bandwidths of the typical (1280x1024) display, you must use the proper 75 ohm coax and connectors, and assemble the circuitry itself in a shielded metal box, if possible. Otherwise, there could be degredation of the displayed video - ghosting, ringing, and less than optimal image sharpness. If you will be making a cable from scratch, there will be some precision (very tiny pins) crimping or soldering needed to construct the VGA and/or 13W3 (typically) connectors as well.
Most common are BNCs - individual coax connectors for each signal - and 13W3 which combines 3 coax and 10 normal signal pins in a single shell. Except for some really strange custom connectors, adapters are available: * VGA to 3, 4, or 5 BNC (might as well get the 5 BNC as the increased cost may not be that great and it is the most flexible should you come across another 'bargain'. * VGA to 13W3. (e.g., Sun monitor). * VGA to MAC (regular DB15). (e.g., Macinstosh monitor).
When your PC boots, it may interrogate the monitor to determine what its capabilities are. With BNC or 13W3 connectors, the needed signals are generally not present. Some manufacturers are addressing this by providing little widget boxes that plug in as part of an adapter cable to provide these signals but these are not common at the present time. Therefore, you may need to take steps in hardware or software to get around this deficiency.
Perhaps that deal-of-the-century doesn't sound so great at this point. Don't give up yet. There are several possibilities. * High-end video cards with compatible scan rates. As noted above, for use with applications that run entirely in windows and/or at a single resolution and scan rate. A separate monitor (or no monitor in case you trust your setup) is used for booting. * Special fixed frequency monitor video cards. These emulate VGA and SVGA video cards as far as the PC's software is concerned but drive the monitor at a fixed (high) resolution and scan rate even when booting (in most cases).
Having been told by all the experts that his monitor was fixed frequency and a pain to use: (From: Malik (firstname.lastname@example.org)). Against all odds i thought what the hell and tried it anyway... And hey, presto! it works perfectly, no problems. I had to feed a vertical sync into the monitor which would not have been possible because the feed for this was not present on the plug. However it was possible to remove one of the unwanted wires in the RGB lead and reconnect it to the unused Vsync input. It appears Sony just fit the appropriate lead/connectors to the monitor depending on its purpose then badge it for Sun, etc. The model number is GDM 17E20 its absolutely a superb monitor... If you can get one I suggest you do. I know there is a 17E10 and 17E11 that are older.... the situation maybe the same with these.
If you already have an investment in a good video card (not a $29 K-Mart special), then this may be a possibility. * Advantages: you may already have one and it will be good for a PC compatible multiscan monitor in the future. * Disadvantages: Not usable for booting and DOS applications. It may not be capable of generating composite sync or sync-on-green (if needed) without an adapter. * Information sources: The Fixed frequency monitor FAQ and Sync-on-green FAQ are available at: http://www.repairfaq.org/ Some other sites with information and links relating to fixed frequency monitors: http://saturn.tlug.org/sunstuff/ffmonitor.html http://rugmd0.chem.rug.nl/~everdij/hitachi.html http://www.midcoast.com/jp/sun/2.html http://www.devo.com/video/ http://www.sunhelp.com/ The Comp.sys.ibm.pc.hardware.video FAQ is available at: http://www.heartlab.rri.uwo.ca/videofaq.html The FAQ has received news.answers approval, so it should be archived at rtfm.mit.edu and all mirrors, as well as in news.answers and comp.answers. * The following company sells various inexpensive fixed frequency monitors and video cards. I have not dealt with them so I have no idea of their quality or customer service. Machias Computer Systems Voice phone: (207) 546-3030. Web: http://www.nemaine.com/~jims
These are special video cards. You remove and mothball your current video card (if you already have one) and replace it with one of these. You then install the special video drivers (where required) supplied with the card. Some models appear to be quite competitive in terms of graphics performance (Windows accelerated, etc.) so these may represent an attractive alternative even for high performance applications like Autocad. After specifying the monitor type and/or scan rate parameters for your monitor, the behavior of the card should be essentially transparent to your software. That is, programs think they are talking to a VGA/SVGA card but the output of the card drives your fixed frequency workstation monitor properly at all times - including booting, DOS games, Windows, etc. * Advantages: full DOS/Windows, possibly high performance (some models claim Windows accelerated video performance), drop-in solution (no adapters, circuits, cables, etc.). * Disadvantages: cost if you already have an expensive video card, possible lack of wide or long term support (these are not exactly Fortune-500 companies). * Information: Mirage and Photon appear to be the most well known of the companies providing fixed frequency video cards. However, the FAQ lists several others as well. The order of these entries is somewhat arbitrary and may change without prior notice :-). In other words, it doesn't represent any sort of recommendation. 1. Mirage Computer Systems, 4286 Lincoln Blvd., Marina Del Rey, CA 90292 Phone: 1-310-301-4541, fax: 1-310-301-4546 Contact: Emil Darmo (email@example.com) Web: http://lainet3.lainet.com/mirage/ 2. PCG Corporation (Photon) Phone: 1-800-255-9893, tel: 1-310-260-4747, fax: 1-310-260-4744 Email: firstname.lastname@example.org Web: http://www.photonweb.com/ 3. Software Integrators, 51 Evergreen Drive, Suite A, Bozeman, MT 59715 Phone: 1-406-586-8866, tel: 1-800-547-2349, fax: 1-406-586-9145 Contact: Joe McCarthy (email@example.com) Web: http://www.si87.com/ 4. MaxVision Phone: 1-800-533-5805 ext. 202 5. STB Systems, Inc. Web: http://www.stb.com/ FTP: ftp://ftp.stb.com/ 6. Mobius Trading Company Web: http://www.ioa.com:80/users/mobius/monitor.html 7. UltraSpec Cables, Inc. Phone: 1-800-622-2537 Web: http://www.ultraspec.com Cables and adapters in addition to a PCI card for using a fixed frequency monitors on a PC. 8. Worldwyde.Com Phone: 1-248-473-1182 Email: firstname.lastname@example.org Web: http://www.worldwyde.com
(Some of these may be listed elsewhere in this document as well.) (From: Tony Chau (email@example.com)). http://altinex.com/ http://www.devo.com/video/ http://www.nemaine.com/~jims/index.htm http://www-dccs.stanford.edu/lists/decstation-managers/hyper94/0074.html http://www-dccs.stanford.edu/lists/decstation-managers/hyper94/0079.html http://www.heartlab.rri.uwo.ca/vidfaq/fixed.frequency.html http://aurora.tky.hut.fi/fixed3.html http://www.si87.com/softfaq.html#3 http://www.mirage-mmc.com/sony/ http://www.mirage-mmc.com/leader.htm http://www.si87.com/ http://www.ioa.com/users/mobius/monitor.html
(From: Karl Ivar Dahl (firstname.lastname@example.org)). I have a SONY GDM 1961 (a.k.a. VRT 19-HA) fixed frequency (sync-on-green) monitor. This monitor displays 1280x1024, but I have recently been able to tweak it to display 1024x768, 800x600, and 640x480! So now I can play Quake full screen under NT and Linux :-) The clue is to reduce the visible resolution and add the missing pixels to the front and back porch. The image of course doesn't fill the entire screen, but it's a *lot* better than having none at all. I have made a page with my experiences with making a fixed-sync monitor work on linux, NT and win95 to help others with access to these extraordinarily cheap and large workstation monitors: * http://www.geocities.com/SiliconValley/Foothills/4467/fixedsync.html
As noted below, this is an experience with one particular video card - I don't even know which one or how old it was. Thus, these comments should only be used as an indication of what kinds of questions to ask when selecting a card and the possible problems you may encounter. (From: Steven Leinwand (email@example.com)). It is true that the most expensive solution (a special video card) is usually the best solution. I bought one a while back, and in the interest of 'truth in advertising' let me describe some of the drawbacks you will experience. In all fairness, I will mention that I haven't tried all the video boards out there, and am basing my comments entirely on my experience. Your mileage may vary. Fixed frequency monitors like those commonly supplied with Sun workstations cannot change video modes like multiscan monitors. In order to get them to work in DOS modes, video card vendors like Mirage and Photon modify the VGA bios on their cards to 'emulate' *some* DOS modes at a fixed scan frequency. This works well in *some* modes, works poorly in others, and doesn't work at all in some. These BIOS mods interfered with motherboard timing on two VLB motherboards. I tested it with four video cards, the problem was the VGA BIOS). Video wouldn't sync after warm-booting. I had to shut the machine off, and wait about 10 minutes. In all fairness, I have not heard of similar problems on ISA and/or PCI cards, so that problem may be on that vendor's VLB boards only. It usually works best in Windows, where the display is always in the same graphics mode, and mode switching isn't an issue. It works for *some* DOS programs, depending on what video mode they try to put the display in. It works poorest on games, which seem to insist on using weird and/or undocumented VGA video modes. At least half my games either wouldn't work, or their image was so small, as to negate any benefit of having a large monitor. ** Modes less than the monitor resolution will usually be displayed at 1/2 the screen size of the monitor ** This was a surprise to me, and was never mentioned in any of the ads for video boards. I've been told this is a fact of physics, and cannot be overcome in fixed frequency monitors. (Editor's note: it can be overcome using a scan converter but this is much more complex than a BIOS change! See the "Notes on Video Conversion" document for further information on scan converters.) I finally sold both monitor and video card, bit the bullet, and bought a 17" SVGA monitor and card. If I didn't have the VGA BIOS timing problems with the VLB version, I might have been able to re-use the video card, but was tired of the hassle. Since I got the monitor for free (obsolete product destined for the dumpster), it wasn't that bad. My advice is ask detailed questions before you buy, get a money-back guarantee, and test with all your applications. If you can't live with the results, exercise your guarantee. Also check out support capabilities. One of those vendors I mentioned was very responsive and helpful. The other one started out awful, but made some progress in responsiveness over time.
(From: Richard Shima (RShima@att.net)). The IBM (Sony?) display 6091-19 is a 5-BNC type, and is, indeed, a fixed frequency type. Therefore, you'll need certain special modes available in a display adapter to accommodate it, beside the correct cable, of course. Take a look at the following site for some interesting info relating to 6091 modes and video cards: http://www.lysator.liu.se/~jonass/6091.html (IBM6091 info) Also, if you like, go to the following IBM Web site for specific monitor features & technical specs covering your 6091: http://www.nz.pc.ibm.com/support/a03e_1de2.html I'm pretty certain that IBM 6091 was actually made by Sony, and, in their better displays, they still use the 5-BNC (separate signal) video cable, i.e., on their current SE series, etc. I'm certain you could buy a Sony (or other) replacement cable that would do the job, tying your display to a PC-type 15-pin VGA/SVGA "D" video connector, once you know you have a video card that will support it.
(From: Wayne Rothermich (firstname.lastname@example.org)) I had to learn what signals my IBM 6091 monitor wanted versus what signals my video card provided by experimenting with a scope and a pulse generator for a day or so. In my case, the monitor wanted inverted polarity on the horizontal sync line. I found that I could provide this by triggering a lab pulse generator from the video card's horizontal sync output, and using the resulting (inverted) pulse to sync the monitor. Fortunately, the timing jitter in the pulse generator was low enough that no horizontal jitter was noticeable on the display. I used the monitor this (rather nerdy) way for a while, and then I noticed a small ad in Nuts and Volts magazine for a moderate cost ($200) translating video card made by a company called Ming. I ordered one, and it turned out to be a modified (new video BIOS chip, a few wire jumpers) Jaton 58P card, which uses the Tseng Labs ET6000 chip. This has proven to be a good solution to my fixed frequency monitor problem. I ran comparative benchmarks using the Landmark PCPRO test program, and the speed of this card - when writing to video RAM - is similar to other high performance (Matrox Millenium 2, Diamond Stealth 3D 2000), cards I have tested recently. Ming makes cards for several different fixed frequency monitors, so they could be a viable choice for many of your readers. You can check their web page at http://www.riverside.quik.com/ming for more details.
(From Arnoud van der Wel (email@example.com)). Well, I did this to two of them about a year ago. Of course I wrote down what I did, so I'll try to reconstruct for you what I did. There are two modifications, one is the H-FREQ control, the other is the H SHIFT VGA control. To boot, you need it to display the standard 31.5 KHz VGA text mode. Turning the H FREQ pot (on the rear edge of the PCB) will eventually give you a display, but it is off-screen to the right. You then adjust the H SHIFT VGA pot (on the right of the PCB) and find that this pot has insufficient range to center the display. The H FREQ pot is 4.7K from the factory. It is in series with an 18K SMD resistor on the solder side of the PCB. I found that I had to turn the 4.7K pot to max resistance to move the display to the left, so I removed the 18K resistor and the 4.7K pot, and replaced them with a 22K resistor and a 10K pot. I was then able to center the display for text mode. The only problem is that the horizontal linearity in text mode is now off. The letters near the right of the screen are narrower than elsewhere. The problem is not serious (a casual observer does not see it) so I can live with that. Moreover, I never use text mode anyway (except during booting and for BIOS setup, etc.) The 320*200 mode (games) also works correctly after this modification. Now, we want it to sync to highter refresh rates, specifically, 1024*768. That is the mode I adjusted it for. All the 1024*768 parameters are separately adjustable from the ones for the other modes, except the H FREQ. The pots that govern this mode are all labeled "4,5", meaning, I presume, that they govern the operation of what the monitor manufacturer calls mode 4 and mode 5. I found these to coincide with H frequencies of over approximately 50 KHz. I found that by tweaking the H freq, I could get the text mode to be all right, *or* the 1024 mode, but not both at the same time. (BTW, I run 1024 with a pixel clock of 77 MHz, H freq. of 57.63, and V freq. of 68.13 Hz. I don't know what the specs for this monitor are, so I thought it was prudent to stay on the low side.) So I needed two instead of one H FREQ pots. I also found that there is a relay click if you throw something over 50 KHz at this monitor. Hence, I tapped the relay coil to give me the 0/12 volt signal to tell me what mode the monitor is displaying. This signal I take to a little PCB that holds my two H FREQ pots, an inverter, and two NPN transistors that switch in one or the other pot instead of the original one. The schematic is shown in ASCII below. Or, see the Gif version provided by: Puiu Chiselita (firstname.lastname@example.org). TO H-FREQ o | +12 VDC +------+-----+ o | | | / / | \ 680 680 \ | / / 100K 1N4148 |/ E | | RELAY o---+--/\/\--|<|--|<|--| PNP +--+ +--+ | 1N4148 |\ C | | | | | | / | | / | / 2.5K \<-+ +->\ 2.5K | 100K \ / / | / | | | | |/ C C \| 1N4148 100K | +----| NPN NPN |---+--|<|--/\/\--+ | | |\ E E /| | | | / | | / | | 100K \ | | \ 100K | | / | | / | | | | | | | | +------+------+-----+-----+ | | _|_ Gnd | | - | +------------------------------------------------------------+ Transistors can be any general purpose type: * Typical NPN: 2N2222, 2N3904, BC547. * Typical PNP: 2N2907, 2N3906, BC557. I added the diodes to make sure we have a real OR circuit here, not a bit of AND left in it, since that would (albeit momentarily) drive the H FREQ up way too high and send the monitor into its OV protection. Now I can tweak the H FREQ pot for both modes separately. To sum up, my 9517 now displays VGA text modes, 320*200, and 1024*768 in approx 70 Hz. When it is warm, I can also get it to display 640*480. I could probably do a fix for that too, but haven't bothered since I don't need that mode. Moreover, I don'thave schematics, so I'm a bit hesitant to continue modifying it, when it already works adequately for my use right now. The H linearity in the 320 and 1024 modes, by the way, exhibits no problems. This solved monitor number one, and oddly enough, when I did monitor number two. I was able to get it working after installing only mod number one. A little help from the VGA card (Diamond Speedstar if I remember correctly) did the rest. So maybe you are in luck and need only one mod. A flexible VGA card definitely helps. (Or good setup-software for the VGA card.) When you are turning all the little presets, be careful not to short the wipers to the chassis... use a plastic tool! The wipers are not insulated from the screwdriver slots. You can easily destroy some of the SMD transistors by doing that. That's what I did, and I had some VERY lucky guesswork in unsoldering them and replacing them by normal transistors (that is what I tend to do when I find a dead SMD transistor...) These are beautiful monitors and well worth modifying. Fortunately, not a lot of people are able to do this, and this means that they are available rather cheaply. :)
(From: Flupke ut Warns (P.O.Langemeijer@student.utwente.nl)). The most important thing is to get the sync pin(s) connected and the horizontal scan rate as close to the required value. There is much more info and links at: * http://www.geocities.com/SiliconValley/Foothills/4467/fixedsync.html
Here is a success story for the Sun 21" fixed frequency color monitor. 0. The only active part in the circuit is a 74HCT86 quad XOR chip. Only one XOR gate is used - to combine H and V sync. All the other signals are wired through to the monitor (using RG59, 75 ohm coax for each of the RGB videos.) (From: Ken Jones (email@example.com)). Disclaimer: I will not be responsible for any damage to your monitor or ego that might be caused by the use of this circuit. I don't know if this works with all VGA Cards. I've tested this with my Matrox Millenium and Mystique VGA Card, and it worked well. But there is a tricky part!!! For all those, who are trying this circuit with their Matrox Card, be sure to accomplish the following steps: 1. Buy all the needed hardware parts - 74HCT86 (TTL-XOR), 0.1uF Capacitor, Print, HF-Box - and assemble it. I use a small HF-Box, to eliminate interference problems. Be sure to make all wires as short as possible! 2. In Win95, go to the Display Properties: * Select MGA-Monitor Panel. * Choose a Monitor which can Display 1152x864. (Hitachi CM2111 for example) * Select this Monitor, and press 'Properties'. * Now select 1152x864x256 or 1152x864x65535 (as you like) and press 'Apply'. * Select the MGA-Settings Panel and increase the Display-Area to 1152x864 too. Press 'Apply' and reboot Win95. Now, your Monitor could work. If not, (as it happened to me...) do the following: 3. Go to the Display-Properties again: * Select MGA-Monitor Panel. * There is a Button named 'TEST!'. (First it was grayed out). Press it. (What for?.. Well, read on) * A Monitor Test-Pattern should appear, nothing special, but there is a small Button, called 'DETAILS'. This is the key for all... * Press 'DETAILS' and a new form appears. Now you can choose Sync-Negotiation, Vertical, and Horizontal, Refresh-Rates, etc, etc... (AHA!) * Set all you need to get your Monitor running. (In my case i changed the horizontal-refresh-rate to 71kHz)
The site below documents in great detail the connection of the Sony GDM-1961 to a running Linux, Win3.1, and Win95. The information should be of use for other monitors as well. * http://www.geocities.com/SiliconValley/Foothills/4467/fixedsync.html
(From: Anders Stenkvist (Anders.Stenkvist@uab.ericsson.se)). I just wanted to share some info about a Sun monitor I recently acquired. It's one of the new 20" multisync monitors you get together with Ultras with part number 365-1335 or GDM 20E20 made by Sony. Searching the net told me it should be possible to connect it to my PC but gave no info on how. So, armed with a screwdriver, an soldering iron and a lot of curiosity a started to investigate my new monitor, and after some iterations I got the following "new" pinout of the 13W3 connector. Analog: 13W3 connector: +----------------- | +------------- | | +--------- | | | +----- | | | | +- horizontal sync (new multisync only) | | | | | | | | | | grey red | | | | | green blue | 1o 2o 3o 4o 5o | | (O) (O) (O) 6o 7o 8o 9o 10o | | | | | | | | | +--- sync common (gnd) | | | +------- | | +----------- | +--------------- vertical sync (new multisync only) +------------------- The monitor works with a PC driver from sony named "SONY multiscan 20se" and is able to do at least 1280x1024 @ 75Hz, that's at least what my video card is capable of. Looking inside it I also found markings for one of the PC-monitor buses used for autoconfig but I have not bothered to get that to work. Any info on that would be appreciated but it does work nicely without it.