GPU is Tseng ET4000/W32P for VLB

Some info I found: https://archive.org/details/tseng-labs-et4000 … age/n9/mode/2up ...I am not using any Monitor ID pins on VGA on monitor that is not working (I simply cut the wires inside the cable) ....does this Tseng need something more than R,G,B,V,H ?

BIOS is by Cardex

Jumpers: https://wiki.preterhuman.net/index.php?title= … le_view_desktop

It works when I put KVM in between of these two.

KVM identifies monitor type?
VLB (~1992-93) was on the cusp of EDID/DDC (1994) so not that, before DDC pins identified monitor capabilities https://en.wikipedia.org/wiki/Display_Data_Ch … l#Physical_link

The monitor is old analog VGA only, 640x480, no 800x600. KVM does not identify monitor because monitor does not have DDC. I tried two Aten KVM's. One very old for AT DIN - 4 ports and one modern USB - 8 ports, both allow the monitor to sync properly. Monitor has only RGB,VH pins connected to VGA cable.

Sorry. I meant KVM identifies itself as some type of monitor, and Tseng might not like floating identify pins. Just a theory. Check KVM output identity pins with multimeter, or open it up

This J101 connector goes to PCB board on monitor. The PCB connector has labels:
T H V B G R.

The "T" has offset position, perhaps it is a label of connector itself and does not have any meaning.

All others H V B G R always contain two pins. One for signal, one for ground. At least that is the assumption. The pins between H and V do have different colours and might not be ground actualy, although I read that H and V sync always have ground as well.

I will measure KVM VGA pins, for sure.

But is there any way how to identify these pins on the monitor? Backplane of monitor says: Model: VC-2EN, Made in Singapore, Dell Corporation, 1992. and states both 50/60Hz.

Orange = H Sync
Blue = V Sync

Not sure about other colours. I guess it does not have any standard, so I connect all of them to GND of VGA cable.

rasz_pl wrote on 2023-03-11, 22:36:

Sorry. I meant KVM identifies itself as some type of monitor, and Tseng might not like floating identify pins. Just a theory. Check KVM output identity pins with multimeter, or open it up

edited my answer regarding connection to the monitor

https://en.wikipedia.org/wiki/Display_Data_Ch … l#Physical_link
ID2 (pin 4) ID0 (pin 11) ID1 (pin 12)
https://pinouts.ru/Video/VGA15.shtml

Yes, I understand. This monitor is color and does not support 1024x768. I will need to somehow identify its pins on PCB while it is being powered on...maybe I did something wrong because it won't switch to 800x600, which is VGA standard. Maybe Blue should not be V Sync....but I did measure it.

you dont need to identify any pins on the pcb. btw 800x600 is not standard VGA, 640x480 (720×400) is max early monitors supported, or rather 31KHz.
take a multimeter and measure resistance between pin 11 and the metal shield on monitors VGA connector
or even better measure all 4 11 12 on the working monitor and compare to not working one

Got it. I took monitor from scrape yard and it had VGA connector cut. I can only guess which wire is 4, 11, 12 pin 😁 ...but I will try something else. Thank you!

aah, I missed it didnt have cable at all when you got it. Solder pin 11 to ground and it should work fine.