How to connect a SUN 20" Premium (Sony) GDM-20D10 monitor to a PC with Windows 95/98/NT

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( You are visitor nr. WEBCounter by GOWEB to this info since 13 April 1998 ).
The monitor type is the 20" SUN Premium (SONY product) GDM-20D10 (Color, build 1994/1995), used with SUN stations. The monitor is controlled with a small remote control unit (SUN part numbers 370-1576 or 370-1705), see page 3 of the GDM-20D10 SUN documentation.

I tested also, without success the SUN 19" monitor GDM-1962 (color, build 1991), see:
SUN monitor GDM-1962 and GDM-1662
See also:SUN monitors "certified" by SUN to be compatible with PCs

The monitor will only give an image when Windows 95 or 98 is active (and also when a DOS window in Windows 95 or 98 ) !!
Starting-up of the PC, protected mode of Windows 95 or 98 and PC BIOS setup are invisible.

Video board

You need a video board in your PC that supports up to Horizontal 81.1 kHz and Vertical 77 Herz,
(It must at least be possible to select a Refresh rate of 75 Hz and resolution 1024 x 768 with 256 colors).
(Hor. freq. = line frequency, Refresh rate is Vert. frequency).

Diamond Stealth video boards perform excellent. I tested my 20" SUN monitor with the following Diamond Stealth video boards:
Stealth 64 Video 2121, Stealth 3D PRO 2240, Stealth II S220 and Stealth Viper 330;
all perform excellent with these frequencies and image matrix settings of 1024 x 768, 1152 x 864 or 1280 x 1024.
The Diamond Stealth 64 video board series come with a set of drivers for DOS on its CD-ROM,
called GO95 that allow you to use the GDM-20D10 also in DOS mode at 1024 x 768.

Provide at least 2 or 4 MB video memory in your video board to see all colors.
The GDM-20D10 works also with: Cirrus Logic 2MB video board (Windows accelerator) at 1024 x 768, 256 colors and the refresh rate 75 Hz under Windows 95 and 98.
It looks that the GDM-20D10 will work with all video boards that support 1024 x 768, 256 colors,
provided that the refresh rate is at least 75 Hz.

20" SUN GDM-20-D10 Monitor frequency data provided by SUN (Febr.1994)

Page 2 of the SUN documentation tells:
"Monitor automatically synchronizes to one of four frame buffer specifications"
(when connected to a SUN station):
    Res.    1280x1024     1152x900     1280x1024     1152x900
    Hor.    81.1 kHz      71.8 kHz     71.7 kHz      61.8 kHz 
    Vert.     76 Hz         77 Hz        67 Hz         66 Hz 

    COMBINED sync. wire for   H + V:   2.5 - 5 V,  75 Ohms 

You may define your "SUN Fixed frequency Monitor" in WINDOWS 95/98 with the file

To set Horizontal and Vertical Frequency settings in Windows 95:

Click the buttons:
Settings -> Control panel-> Display -> Settings -> Advanced properties -> Monitor -> Change -> Show all devices
-> EIZO -> EIZO 9500 ->next -> next -> Finish

-> Refresh -> Refresh rate 75 Hz -> Apply -> OK -> Keep: Yes

To set Horizontal and Vertical Frequency settings in Windows 98:

Click the buttons:
-> Settings -> Control panel-> Display -> Settings -> Advanced -> Monitor -> Change -> Next -> Display a list of ... -> Next -> Show all hardware -> EIZO -> EIZO 9500 ->next -> next -> Finish

-> Refresh -> Refresh rate 75 Hz -> Apply -> OK -> Keep: Yes

In Windows NT 4, simply select "Refresh rate = 75 Hz"

Select one of the WORKING following combinations:
  Res. 1024x768   Refresh rate  60 Hz  DID NOT SYNCHRONIZE
       1024x768                 72 Hz  DID NOT SYNCHRONIZE
       1024x768                 75 Hz  WORKED OK
       1024x768                 85 Hz  WORKED OK

  Res. 1152x864   Refresh rate  60 Hz  DID NOT SYNCHRONIZE
       1152x864                 70 Hz  WORKED OK
       1152x864                 75 Hz  WORKED OK

  Res. 1280x1024  Refresh rate  60 Hz  WORKED OK
       1280x1024                72 Hz  WORKED OK

Note that:
Hor.  freq. = Line frequency (nr of lines per second),  
Vert. freq. = Refresh rate and
Hor.  freq. = Vert. freq. x number-of-lines.
Vert. Res.  = number-of-lines (minus about 30 invisible lines)
Do not use the refresh rate "Adapter default" or "Optimum" !
Check the Refresh Rate after changing the resolution settings.
Some screen savers or games also change the Refresh Rate from 75 Hz to something else, then your screen changes to a black plane ...

When your existing monitor does not support the frequencies of the SUN...

Switching in Windows 95 or 98 from a "slow monitor" to the SUN monitor is tricky,
you have to select the settings for the SUN monitor on the Windows 95 or 98 control panel,
to interchange the monitor connectors and to confirm on the screen
the settings for the newly connected monitor, all within 15 seconds .

Horizontal and Vertical synchronization signals from the PC must be combined to one signal

The VGA V and H signals from the videoboard of a PC:
H is high (+5V.) with pulses to zero (pin 13),
V is zero with pulses to +5V.(pin 14).

The combined sync that the GDM20D10 monitor needs is about +3 V.
with Hor. pulses going down to zero and Vert. pulses going up to +5V.

I connected the Vert. of my video board directly to the SUN combined sync wire and
the Hor. of my video board via a capacitor of 0.2 microFarad,
to combine the Hor. and Vert. sync signals of the videoboard to one combined sync signal,
and to separate their DC levels.
The average voltage on the combined sync. entry is then about +2,2 V.
Even the shortest direct contact between H. an V. may damage your videoboard.

Software to get a combined synchronization signal out your video card !
When your cable adapter does not provide the sync. combiner or capacitor, the following may help:
From :
you can download the file: pstrip.exe (660 KByte)
This is a program for a number of video cards that allows to get a combined sync. signal out of your video card.

Connector and cable

Four possible ways to get the cable adaptation that you need:
  1. Buy a so-called cableadapter. This cableadapter must have a female
    SUN Video DB13W3 connector and a male VGA 15-pin Sub-D connector,
    Such a cable adapter is marketed by:

    25 January 2002, a new supplier came up:

    Their adaptercable contains the 0.2 microFarad capacitor.

    Already for a long time on the web: in USA,

                                         40 Riordan Place 
                                       Shrewsbury, NJ 07702
                      Phone Lines North America 1-800-622-2537 Int'l +1-732-450-1900
                       Fax Lines North America 1-800-222-5337 Int'l +1-732-741-0300


  2. The short adapter cable: 530-2357-01 BERGCAD 3598, available from SUN does not have
    the capacitor to combine the V and H sync signals, so your screen remains black !!
    However it is possible to use this SUN cable 530-2357-01 after some "electronic surgery":
    The cable has melted connectors so you cannot open them, but you can open the cable itself.
    H sync. comes from pin 13 of the VGA 15-pin via the brown wire to pin 5 of the female DB13W3.
    V sync. comes from pin 14 of the VGA 15-pin via the orange wire to pin 7 of the female DB13W3.
    Connect the capacitor between the orange and the brown wires of the cable.
    Check the reliability of the connections with the capacitor.
    Do not forget to restore the interconnection between the two ends of the shielding of the cable!
    IT WORKS !

  3. Cut off the connector of the SUN monitor cable and connect a male
    AMP VGA connector to the cable end of the monitor
    and house the (miniature!) capacitor also in the VGA connector house;
    looks nice, but the cable of the SUN is short, about 60 cm (2 feet).

  4. Cut off the connector of the SUN monitor cable and use a second cable end
    with a male VGA connector and mount an intermediate box
    between the two cable ends to make the correct interconnections
    between the wires of the two cable ends and to house the capacitor of 0.2 microFarad.
    I pasted such a box to the side of my SUN monitor; it works excellent.
    The cut off SUN cable end may also be connected again, via a selector switch,
    to switch the monitor between a SUN station and the PC.
    Diagram VGA 15 to DBW13W3 with capacitor
    Diagram VGA 15 to DBW13W3 with capacitor, Diagram made by Sven Löschner
    Diagram for switch connection to PC and SUN station

VGA 15-pin Sub-D male connector (At the monitor cable)

Pin Name Description

1 RED Video (75 ohm, 0.7 V p-p)
2 GREEN Video (75 ohm, 0.7 V p-p)
3 BLUE Video (75 ohm, 0.7 V p-p)
4 not used
5 GND Ground
6 RGND Red Ground
7 GGND Green Ground
8 BGND Blue Ground
9 not used
10 SGND Sync Ground, connect to Grey Composite Ground wire of monitor (13W3 pin 10)
11 not used
12 not used
13 HSYNC Horizontal Sync, connect via 0.2 microFarad capacitor to White Composite Sync wire of monitor (13W3 pin 5)
14 VSYNC Vertical Sync, connect to White Composite Sync wire of monitor (13W3 pin 5)
15 not used

See also VGA 15 pin connector layout and
VGA 9 pin connector layout

SUN Video male connector ( DB13W3 )
(At the monitor cable)

Pin Name Description

1 do not use
2 do not use
3 do not use
4 do not use
5 CSYNC Composite Sync , White wire
6 do not use
7 do not use
8 do not use
9 do not use
10 CGND Composite Ground, Grey wire
R RED Coax, Red
G GREEN Coax, Brown
B BLUE Coax, Blue

See also DB13W3 connector layout

GDM-20D10 Monitor documentation provided by SUN (6 pages)

SUN Part Number 801-3817-10 Rev.B February 1994
Read the files with the Adobe Acrobat reader, downloadable from Adobe.
GDM-20D10 SUN documentation, Page 1 Cover page
GDM-20D10 SUN documentation, Page 2 Specifications
GDM-20D10 SUN documentation, Page 3 Remote control unit, front and rear panel
GDM-20D10 SUN documentation, Page 4 Power, Mains spec
GDM-20D10 SUN documentation, Page 5 Setting up, adjusting
GDM-20D10 SUN documentation, Page 6 Trouble shooting

Links for useful other information:

JAPANESE solutions for the GDM-20D10 monitor to a PC with Windows :
(Very good English info, excellent technical description)
Let's connect your SUN monitor to a PC/AT machine!!
H and V combined via HCT86 CMOS:

Hans Leibbrandt,
Kievietlaan 4, 5683RC Best, The Netherlands

You can e-mail me for more info: e-mail:

First issue: 13 April 1998.
Last update: 18 September 2006.