Approaches to Using Fixed Frequency or Non-Standard Monitors on PCs


[Document Version: 1.48] [Last Updated: 05/25/1998]

1. About the Author & Copyright

Approaches to Using Fixed Frequency or Non-Standard Monitors on PCs

Author: Samuel M. Goldwasser
Corrections/suggestions: | Email

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:

  1. This notice is included in its entirety at the beginning.
  2. There is no charge except to cover the costs of copying.

2. Disclaimer

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.

3. Introduction

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

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.

4. Problems with fixed frequency monitors on PCs

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.

5. Scan rate issues

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,

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

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).

6. Sync options - separate, composite, sync-on-green, sync polarity

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.

7. Connectors

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).

8. Plug-and-play

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

9. Alternatives to the dumpster

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

10. Then again, maybe it will work

Having been told by all the experts that his monitor was fixed frequency and
a pain to use:

(From: Malik (

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.

11. High-end video cards

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:

  Some other sites with information and links relating to fixed frequency

  The FAQ is available at:

      The FAQ has received news.answers approval, so it should be archived
      at and all mirrors, as well as in news.answers and

* 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.

12. Fixed frequency monitor cards

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

* 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 (

  2. PCG Corporation (Photon)
     Phone: 1-800-255-9893, tel: 1-310-260-4747, fax: 1-310-260-4744

  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 (

  4. MaxVision
     Phone: 1-800-533-5805 ext. 202

  5. STB Systems, Inc.

  6. Mobius Trading Company 

  7. UltraSpec Cables, Inc.
     Phone: 1-800-622-2537

     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

13. Additional fixed frequency monitor information links

(Some of these may be listed elsewhere in this document as well.)

(From: Tony Chau (

14. Check and dirty way to display lower resolutions on fixed frequency monitor

(From: Karl Ivar Dahl (

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:


15. Steve's experience with a special video card

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 (

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

** 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.

16. IBM6091 monitor information

(From: Richard Shima (

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:  (IBM6091 info)

Also, if you like, go to the following IBM Web site for specific monitor
features & technical specs covering your 6091:

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.

17. Using IBM 6091 monitor on PC

(From: Wayne Rothermich (

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 for more details.

18. Modifying an IBM9517 XGA monitor for SVGA operation

(From Arnoud van der Wel (

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

                                           TO H-FREQ
                              +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.  :)

19. SVGA to Sun/Sony GDM1960

(From: Flupke ut Warns (

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:


20. SVGA to Sun fixed frequency monitor - complete solution

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 (

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

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...

   * Set all you need to get your Monitor running. (In my case i changed the
     horizontal-refresh-rate to 71kHz)

21. Sony GDM-1961 Fixed Frequency Monitor on PC

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.


22. Sun 365-1335 or Sony GDM20E20 monitor on PC

(From: Anders Stenkvist (

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.

Written by Samuel M. Goldwasser. | [mailto]. The most recent version is available on the WWW server [Copyright] [Disclaimer]