VOGONS


First post, by butjer1010

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Hi,
i need help from geniuses here!!
I have one VLB card i bought few days ago that has some weird problem. Cards works ok until it starts to load DOS. Than the picture starts to blink (maybe every second or two). I tried to enter Prince of Persia, and i played game for almost 15 minutes, and it has blinked maybe every minute or so, but no freezing or artefacts?!? It is AMD DX4-120MHz computer with 16MB FPM RAM, and Abit AB-PW4 board. Other VLB card (Cirrus GD5428) works fine.
What could be the problem? I have changed 4 small 10uf capacitors, but the problem remained. Could it be some logic chip or memory, or even oscillator?
Thanks in advance

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Last edited by butjer1010 on 2024-12-08, 15:46. Edited 1 time in total.

Reply 1 of 11, by Horun

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My guess: incompatible video ram is creating the issue. The main/soldered ram chips are TC514256AJ-70 standard DRAM but those ram upgrade chips AS4C256K16E0-50JC are EDO.
Try this: remove the upgrade chips and see if you still have an issue. If you do still have the issue it is something else, use a pink end of pencil eraser and gently erase clean the contacts, then use some 99% IPA and wipe them clean again.
Then try again (without the EDO ram installed)....am fairly sure EDO was not supported until the S3 Trio chipsets iirc and yours is a 805....and mixing types is always bad

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 2 of 11, by butjer1010

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Horun wrote on 2024-12-08, 05:22:

My guess: incompatible video ram is creating the issue. The main/soldered ram chips are TC514256AJ-70 standard DRAM but those ram upgrade chips AS4C256K16E0-50JC are EDO.
Try this: remove the upgrade chips and see if you still have an issue. If you do still have the issue it is something else, use a pink end of pencil eraser and gently erase clean the contacts, then use some 99% IPA and wipe them clean again.
Then try again (without the EDO ram installed)....am fairly sure EDO was not supported until the S3 Trio chipsets iirc and yours is a 805....and mixing types is always bad

Hi, thanks man, but i forgot to add that those RAMs weren't there until last night 😀 I tried to add them from one S3 i found it doesn't work at all, so i tried to see if there is any change. So, it is same without them. But if You think this could be the ram problem (maybe main RAM), could i play game like POP without any artifacts or crashing?

Reply 3 of 11, by konc

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Despite the fact than another card works fine on the monitor, have you tried a different monitor just to rule it out? Or are you somehow else confident that it's the card's problem?

Reply 4 of 11, by butjer1010

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konc wrote on 2024-12-08, 09:53:

Despite the fact than another card works fine on the monitor, have you tried a different monitor just to rule it out? Or are you somehow else confident that it's the card's problem?

Yes, i tried on 2 computers (one 100MHz AMD 486, and this 120MHz), and few monitors. Any other card i connect on those 2 computers works fine 🙁

Reply 5 of 11, by Unknown_K

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Your picture is blurry but the main S3 chip has 2 lines soldered together (could be that way from the factory), and also it looks like top right corner (second down) has a broken lead touching the one below it.

Collector of old computers, hardware, and software

Reply 6 of 11, by butjer1010

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Unknown_K wrote on 2024-12-08, 12:15:

Your picture is blurry but the main S3 chip has 2 lines soldered together (could be that way from the factory), and also it looks like top right corner (second down) has a broken lead touching the one below it.

I think those are ok, hope this picture is better? Those two connected are "factory connected" 😀

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Reply 7 of 11, by butjer1010

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One thing i could do now is to reflow all the solder joints, maybe a little bit of hot air with flux on main memory chips.... But if someone has better idea, please help 😀

Reply 8 of 11, by butjer1010

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I took another 486 from my collection, and it was Cyrix DX40MHz, and the card works fantastic!!! without any issues??? So the problem could be in some frequencies on faster CPUs (VLB or ISA speeds)?

Reply 9 of 11, by rasz_pl

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blinks = screen loses sync. Normally I would blame the LCD screen first, but maaaaybe might also be caused by noisy power to the card.

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor

Reply 10 of 11, by butjer1010

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rasz_pl wrote on 2024-12-08, 15:08:

blinks = screen loses sync. Normally I would blame the LCD screen first, but maaaaybe might also be caused by noisy power to the card.

Since You are the second guy who pointed me to the LCD, i tried to connect it to my older LCD, and it works normally!!! Can't believe it didn't work on two LCDs, and it work on third!!!! Thanks a lot all of You, will change this to solved 😀

Reply 11 of 11, by rasz_pl

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Open OSD menu while in game that was blinking and check what parameters it is reporting - resolution, refresh, Video clock. Might be something borderline standard like 76Hz Vsync while LCD monitor is specced at 75Hz max. I think some vga chip vendors had utilities for configuring output refresh rates.

Had same problem with my modern 23' Dell blinking maybe once a day when "overclocked" to 85Hz.

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor