VOGONS


First post, by Ydee

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Seems I have bad luck.
About two weeks ago, I bought an X700 PRO graphics card. It was perfect for the build with PCIE slot and W98SE. I put a new paste under the cooler (AC Silencer) and put the heatsinks on the mosfets, the card worked perfectly (I played games on it) until yesterday.
Yesterday, when I tried to turn on the PC, it didn't respond. Ooops, what is wrong? Ah, the propellers on the fans just moved and stopped again. I thought it would be short-circuit protection in PSU and yes: after removing the VGA, the computer started up normally (with a different VGA). So, it must be a short circuit somewhere on X700. But I have no idea what to focus on: nowhere on the card did I find any burnt or visibly damaged component. It annoys me because there's no much PCIE VGA offers with drivers for the W98, this one I came across after a long time by accident.
Before I take her to the recycling yard, does anyone have any idea what to target and what to check?

Reply 1 of 7, by Zerthimon

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The top right heatsink on the MOSFETs looks like it's shorting the caps. Remove it and try again.

Reply 2 of 7, by Ydee

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Thank you for tips, but it is only bad angle view - when I installed the heatsinks, I was careful not to short-circuit anything and the card would then work for around 2 weeks without problems.

Reply 3 of 7, by Zerthimon

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Yeah, now I see, it's ok.

Reply 4 of 7, by disaster

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Hello
What did you use for mounting heatsinks on MOSFETs?

Reply 5 of 7, by texspex

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Probably first would be to check shorts to ground on +12V, Vcore and Vmem.
Since this card doesn't have a PCI-E power connector, all +12V comes from the PCI-E edge connector.
Looking at the card the first 3 pins from the left would be +12V.
https://pinoutguide.com/Slots/pci_express_pinout.shtml

Vcore probably should be measurable from the back side capacitors behind the core.
Vmem from the capacitors next to the memory chips.
And lastly shorts from +12V to Vcore or Vmem.

Here's a "stabbing guide", but it's for more modern cards. But the principle is the same.
https://www.youtube.com/watch?v=vHGn2pZ0Cv8

Reply 6 of 7, by Ydee

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@texspex: thank you very much for your advice - I'll try to find the source of the problems and your tips are usefull. Is it possible to measure transistors directly on the card in the circuit or not (I am afraid no)?

@disaster: silver heatsink was rest from AC Twin Turbo PRO kit, so 2 of them had original thermotape, on last one I added this: http://www.akasa.co.uk/update.php?tpl=product … odel=AK-TT12-80

Reply 7 of 7, by texspex

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Ydee wrote on 2023-08-14, 09:54:

@texspex: thank you very much for your advice - I'll try to find the source of the problems and your tips are usefull. Is it possible to measure transistors directly on the card in the circuit or not (I am afraid no)?

You can measure it in-circuit, but if you find one shorted it's best to desolder and test it out of circuit again to make sure.