Help to repair Hercules Dynamite VLB \ VOGONS

Help to repair Hercules Dynamite VLB

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First post, by Jackhead

Posted on 2025-03-21, 15:26

Jackhead Offline

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I bought a VLB Graphics card as non working and trying to repair it. First at all i checked the 5v line on the ISA and VLB . No short.
After that i pluged the card into my 486 but i got no signal out.
I notice the VGA plug was really bad and replaced it. I also replaced the clock quarz.
There was a damage on the 5v gnd pins on the isa line, i add some solder for better connection.
Any idea what i can check next?

The attachment IMG_8220.jpeg is no longer available

Last edited by Jackhead on 2025-03-21, 15:48. Edited 2 times in total.

Reply 1 of 9, by zb10948

Posted on 2025-03-21, 15:40

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Does the computer work with the card in? Normal beep and POST?

Reply 2 of 9, by Jackhead

Posted on 2025-03-21, 15:42

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no it wont boot at all. No beep, nothing. My CRT say no Signal.

Reply 3 of 9, by zb10948

Posted on 2025-03-21, 16:09

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Does the computer start POSTing if you remove the video bios eprom?

Reply 4 of 9, by Jackhead

Posted on 2025-03-21, 16:16

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zb10948 wrote on 2025-03-21, 16:09:

Does the computer start POSTing if you remove the video bios eprom?

i removed the bios chip, still no posting.

Reply 5 of 9, by zb10948

Posted on 2025-03-21, 16:25

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Ok, so in direction of electrical problem.
Have you done a thorough visual inspection? It appears to me, on a picture, there is via damage around the C36 label just above the 14.31 MHz crystal

Reply 6 of 9, by Jackhead

Posted on 2025-03-21, 16:46

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good eye, i checked it but lines are ok , only flux or dirt.
i dont see any damage under my scope.
considering the two damaged isa pins im atm thinking about the video memory glock generator the ICS2494AN.
But i dont know if that chip can did result the problem.

Reply 7 of 9, by zb10948

Posted on 2025-03-21, 19:04

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The ISA contacts might've been just worn out by janking the card out of the slot with pivot being in the middle.

Also there are some reference designs in this document
http://www.bitsavers.org/components/tsengLabs … roller_1990.pdf

But it seems to be based on 4 discreete crystals and not a single clockgen.

Reply 8 of 9, by Jackhead

Posted on 2025-03-22, 10:46

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i found the issue! Some short on the GPU lines. reflowed and card is back to life!

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Reply 9 of 9, by zb10948

Posted on 2025-03-22, 13:51

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Great!

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