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Acer 486 now hang during post [SOLVED: small crack on PLCC socket]

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First post, by Rav

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Hi.

My 486 system which used to work just fine (was on for many hours, almost every day, no issue), just decided I would not finish posting
Board -> download/file.php?id=158226

When my custom option ROM is removed, It "POST" (check the ram, etc, etc) then then screen clear then I only get a flashing cursor. Normally after the post, the screen clear and display a system summary on top then boot.

When my custom option ROM is in, it "POST" (check the ram, etc, etc) then then screen clear and display the messages from my option rom then hang there, cursor flashing after the last character of the rom messages.

So I assume it append between "Load all options room" and "Display Summary".
I did try swapping the RAM, removing all ISA cards, removing all IDE devices, disabling the cache.

Oh, and I can enter the BIOS if I press CTRL-ALT-ESC before it hang.

Can the BIOS be corrupt somehow? I would assume it should throw an error if it was the case.

Last edited by Rav on 2025-01-18, 21:07. Edited 1 time in total.

Reply 1 of 2, by Rav

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Well, I unbuilt the whole thing

Dusted out all the dust

Rebuilt it without the case on the kitchen table....

And it work just fine.

It's a ghost or something!

Reply 2 of 2, by Rav

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Well, I think I found the problem, there is a small crack one the plcc socket for the video memory (I populated the right one long ago)

So contacts break sometime probably. While I got it working earlier, I moved it to where it belong and then It began to have issues (like network card stopping working even if the eeprom load from it)...
I deoxited and reseated the video ram chip and now I was able to get it working back properly, stress testing ongoing since about an hour.
Theses are a pain to replace so ideally I would just solder the memory chip on the board. But the ISA raiser slot is like almost touching it and I can't fit in properly with the iron so I will wait until I have my second system completed (With a pc chip M919) then I will just do it.

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