[SOLVED] 386sx16 motherboard doesn't post anymore \ VOGONS

[SOLVED] 386sx16 motherboard doesn't post anymore

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First post, by MMaximus

Posted on 2019-05-22, 21:11

MMaximus Offline

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System was working well until today when I removed a network card from it to test some XT-IDE stuff - now it doesn't post anymore 😕

Keyboard LEDs initialise but there's no display signal whatsoever - I have tried with different video cards (EGA and VGA). I 've also removed all cards from the system (except the SB 2.0) and the same thing always happen. I don't think I've done anything bad, like shorting something and stuff. I haven't heard any suspicious noise or noticed any burn smell either.

Diagnostic card gives the code "0403". I've looked at the manual of the diag card but i'm having a hard time understanding it. First of all I don't understand why there are two set of two digits when the manual gives a list of error codes matching only a single set of two digits. Do I need to focus on "04" or "03"? Any idea how to take the troubleshooting further?

Last edited by MMaximus on 2019-05-23, 19:55. Edited 1 time in total.

Hard Disk Sounds

Reply 1 of 5, by retardware

Posted on 2019-05-22, 21:50

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Use the switch to scroll through the Post Codes.
Write them down.
And say what BIOS you have.

Reply 2 of 5, by Caluser2000

Posted on 2019-05-22, 21:58

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Got a spare psu laying around? Remove the SB card as well.

Last edited by Caluser2000 on 2019-05-22, 22:11. Edited 2 times in total.

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 3 of 5, by rasz_pl

Posted on 2019-05-22, 22:02

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soo, have you tried putting that network card back in? 😀 maybe it was the only component left with working capacitors on 5V line doing filtering
also look into ISA slots if any pins arent misaligned/bend/shorted

Open Source AT&T Globalyst/NCR/FIC 486-GAC-2 proprietary Cache Module reproduction

Reply 4 of 5, by Deunan

Posted on 2019-05-23, 07:42

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You didn't say if it was AMI or AWARD BIOS (or something else maybe) but that's a very early error code - possibly keyboard or CMOS. All other stuff is integrated into a single chip on most 386 mobos (especially SX ones) so it could also mean that chip has developed a fault. Could be a cracked solder under pin from the mobo flexing during card removal. These are 30-year old PCBs.

Still, I'd check the battery first. Then the keyboard - does it do anything more/less when it's disconnected? Finally the standard approach to such problems - take the mobo out, remove all ISA cards except test card, use a different PSU. If the code is still the same then start looking for copper/solder cracks and faulty caps as well.

Reply 5 of 5, by MMaximus

Posted on 2019-05-23, 08:43

MMaximus Offline

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Thanks everyone for the helpful suggestions. Well, what do you know - I unplugged the battery pack and plugged it again and the board now posts! I guess the CMOS settings got corrupted somehow? Or I changed a setting I don't remember changing...

Forgot to mention the board has an AMI Bios.

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