Help me fix a VLB VGA card with a strage issue? \ VOGONS

Help me fix a VLB VGA card with a strage issue?

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First post, by appiah4

Posted on 2022-09-21, 10:53

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A friend sent me their VLB VGA card that started exhibiting a strange issue. The card in question works fine in text modes, but in graphics modes it has strage bars and squares missing on the screen. Please see below for some examples:

The card is not exactly in immaculate condition, it has obviously been previously stored unprotected in a box or somet such, it has quite a few scratches and some corrosion. I'm guessing it's either a memory chip gone bad, a corroded via or a memory trace that got scratched.. Before I pick up a multimeter and start hunting for a broken trace, does anyone have any other ideas/diagnosis or suggestions? It is also suspicious to me that the issue seems to be present only on sprites and not static images.. So maybe it's actually not memory related but another kind of error?

I will post photos of the card later tonight.

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Reply 1 of 9, by Babasha

Posted on 2022-09-21, 12:37

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Its memory (no contact, jammed pins or just dead memory chips(s) or main chip) or scratches on board

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Reply 2 of 9, by rasz_pl

Posted on 2022-09-22, 11:52

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good quality pictures of the card would be more helpful 😀

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Reply 3 of 9, by appiah4

Posted on 2022-11-02, 07:42

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OK, so sorry for being a bit late with the reply on this but life got in the way.. So here are the detailed photos of the card, front and back. Any help with diagnosis will be welcome.

Out of curiosity, can the TL-866 II test SDRAM chips?

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Reply 4 of 9, by rasz_pl

Posted on 2022-11-02, 08:31

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As expected card looks like someone danced on it 😀 left edge has few scrapes, C12 crushed, C13 missing? bios sticker all scratched up. Those arent the source of your problem, but evidence of physical abuse. A good once over with soldering iron and magnification would be a good start.
afaik 866 cant test sdram, only static ram

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Reply 5 of 9, by appiah4

Posted on 2022-11-02, 09:05

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C13 is by default not factory installed. C12 seems a bit crushed but not too bad. There are a lot of scratches in the memory area and I will go over them all with flux + slodering iron and see if that helps. I wish I could test the RAM modules though 🙁 I think I'll use some RAM from another 5428 card I have on this to see if that fixes the issue as well. Still hoping someone can notice a cut trace that I missed on the photos.

The most probable one I can see is this (circled in red) which seems to be a line connecting to the DATA pins of one of the SDRAM chips..

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Reply 6 of 9, by r00tb33r

Posted on 2022-11-02, 09:33

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^ To my eyes that looks like some solder flux next to the large solder blob.

TBH I don't see anything obvious on this card.

Sadly I too have a similar vintage Cirrus Logic card with a fault and no physical damage.

Reply 7 of 9, by Babasha

Posted on 2022-11-02, 10:12

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Isa and vlb connectors need some cleaning with stationary eraser)))

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Reply 8 of 9, by mkarcher

Posted on 2022-11-02, 23:10

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appiah4 wrote on 2022-11-02, 09:05:

The most probable one I can see is this (circled in red) which seems to be a line connecting to the DATA pins of one of the SDRAM chips..

It's not SDRAM! It's perfectly normal fast page mode DRAM (asynchronous) organized as 256k x 4 (commonly called 44256 or 414256). To test for dead RAM chips: Swap chips on the board, and check whether the jail bars move to different columns.

Reply 9 of 9, by pentiumspeed

Posted on 2022-11-03, 00:05

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Following this thread as have exact same issue, missing graphics in jailbars.

Cheers,

Great Northern aka Canada.

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