VOGONS


First post, by mrwolf

User metadata
Rank Newbie
Rank
Newbie

Hi!

First of all, sorry for my English I'm not a native speaker.

I have some problems with a Diamond Monster 3D Rev. E Voodoo 1 card.

The card is detected in Win98 without any issues, mojo.exe shows no problems with enabled debug logging.
Even 3DMark99 runs just fine with ~1800 points.
But I tried with 3 different LCD displays, 3 different cables with the same result: No signal
I'm testing without a pass-through cable with 2 monitors.
Tested in 3 different motherboards, same results.

Things I did so far:
- checked the pins of the 3dfx chips under a microscope looks ok
- measured the RGB,H-SYNC,V-SYNC output voltages coming from the VGA output connector. I used a cheap multimeter and a copper cable, the readings were ok to me.
RGB was between 0-0.5V, hsync,vsync was between 3-4.3V
- checked the components around the DAC for short, nothing

This is my first attempt to repair this kind card, so I really appreciate any advice!
Thanks in advance!

Reply 1 of 7, by Thermalwrong

User metadata
Rank Oldbie
Rank
Oldbie

Hi there 😀

What happens if you try to use the pass-through cable for the display?
Also, is the monitor actually saying "No Signal" or is it displaying black?
If your multimeter supports Hz / clock measurement you can jam the positive probe into the VSYNC / HSYNC pins to see what the frequency of those presently is - I would've thought you'd have a display if the hsync and vsync are there even if it's displaying all black.

If the mojo test all looks good then that means the digital side of the RAMDAC is functional but perhaps there's a problem with the 3384Q display switch chip or the analogue power / outputs of the RAMDAC - you can see how I fixed mine here: Re: What retro activity did you get up to today?

Reply 2 of 7, by mrwolf

User metadata
Rank Newbie
Rank
Newbie

Hi,
Thank you very much for your help!

Sadly I don't have a pass-through cable at the moment but the switching part is working I think, because without running something in 3D there are 0Vs on the RGB pins. After starting a game I can measure changing voltage on the RGB pins.

The monitor says no signal, the led is blinking then sometimes the led is on for a while then blinking again.
I will receive my oscilloscope this week, and will check what's going on the hsync/vsync side.

I also suspect that the culprit is on the analog output line.
Actually the card is in really good shape, no broken traces or something like that.

I think it's time to order some replacement RAMDACs, just in case 😁

Reply 3 of 7, by Imperious

User metadata
Rank Oldbie
Rank
Oldbie

I assume from the 3dmark score You are running this on something period correct?
Does You monitor support higher than 60hz? You can force the refresh rates to 60hz in the control panel.
Voodoo 1 cards sometimes don't work on higher mhz systems.

Dos 3dfx version of Tomb Raider is a good test as it avoids any possible windows software and driver issues.

Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.

Reply 4 of 7, by mrwolf

User metadata
Rank Newbie
Rank
Newbie

Hey!
Thank you for the hints!

I've already tested it in 3 different boards, 430VX(P1 133Mhz)/440BX/some SiS soscketA board, and now I retested it in a 430HX socket7 board(6x86 120Mhz).
Also tried with SET SST_SCREENREFRESH=60 and SET SST_SCREENREZ=640 in autoexec.bat

Same results, no signal.

Reply 5 of 7, by mrwolf

User metadata
Rank Newbie
Rank
Newbie

News!

I found a 2.5m long VGA extender cable, and checked the pass-through.
No signal either.

The cable itself looks ok, tested as an extender. The display became a little bit dimmer but otherwise works ok.

Maybe the QS3L384? How does the VGA signal leave the Voodoo 1? 😀

Reply 6 of 7, by Thermalwrong

User metadata
Rank Oldbie
Rank
Oldbie
mrwolf wrote on 2023-12-14, 11:34:
News! […]
Show full quote

News!

I found a 2.5m long VGA extender cable, and checked the pass-through.
No signal either.

The cable itself looks ok, tested as an extender. The display became a little bit dimmer but otherwise works ok.

Maybe the QS3L384? How does the VGA signal leave the Voodoo 1? 😀

Check out this post, your Diamond card should be essentially the same arrangement: Re: 3Dfx Voodoo 1 - Low level hardware information and diagnostics thread
I'm not really sure what my notation meant, does VGA1 connect to VGA2? What's VGA2? How does that differ from pass-through? ehh - have a look at the really well laid-out schematic that Anthony posted in the last post, page 8 of that covers the switcher in a meaningful way 😀

Reply 7 of 7, by mrwolf

User metadata
Rank Newbie
Rank
Newbie

Good news!

Finally I was able to repair the card, and it's working properly.

Just a short memo, maybe helps some in the future:

- After getting the right tools(scope etc...) and some skills 😁, I was able to prove that the culprit must be the initial suspect, the display switch IC on the back of the card.
- Between the blue VGA connector and the RAMDAC, on the R35 resistor I was able to measure the correct HSYNC signal, but at the same time on the VGA output there were nothing . The trace from that resistor goes into the display switch IIRC.
- So based on this observation after I got a donor card, I replaced the display switch IC and that solved the problem.

@Thermalwrong
@Imperious
Many thanks for you help, your links and advises really helped me to make the next steps with the repair!