VOGONS

FIC VA-503+ schematic?

Topic actions

First post, by hellslinger

Posted on 
User metadata
Rank Newbie
Rank
Newbie

I'm looking for a schematic for a FIC VA-503+ rev 1.2A motherboard (Super Socket 7). I realize it's likely impossible to find, but it's worth a try. I just got a very clean board that will not beep or POST with any combination of supported CPUs, SIMMs/DIMMs, or power supplies (AT and ATX). There was a tiny bit of corrosion on the South Bridge pins, but I cleaned them off, resoldered, and verified continuity.

I recapped it and the verified the voltages on the Vcore regulator (big FET/Schotky combos) and ~3.3V regulator near the DRAM. I have another nearly identical VA-503+ that works and compared the voltages.

I tried a POST code debugger in both the ISA and PCI slot and the last code I see is 4F, which has to do with password and security for Award BIOS, I believe, but the working board shows that too.

Any suggestions or documentation someone might have would be greatly appreciated!

Reply 1 of 2, by rasz_pl

Posted on 
User metadata
Rank l33t
Rank
l33t

sadly no diagram for that one, here a couple era appropriate ones including pretty close MVP4 Gigabyte GA-5VMM Re: 430VX or 580VPX schematics

Since you have another one narrowing it down seems doable. Im guessing you tried swapping bios chips and cpus.

>last code I see is 4F

at this point in time all the magical security/passwords were still stored in regular CMOS ram, thats inside South Bridge and since

> There was a tiny bit of corrosion on the South Bridge pins, but I cleaned them off, resoldered, and verified continuity.

I suspect there might be more hiding somewhere, under chips, under slots, under South Bridge itself, most insidious kind is eaten VIA - looks like a black dot inside via but in reality no connectivity to the other side

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

Reply 2 of 2, by hellslinger

Posted on 
User metadata
Rank Newbie
Rank
Newbie
rasz_pl wrote on 2026-02-25, 23:36:
sadly no diagram for that one, here a couple era appropriate ones including pretty close MVP4 Gigabyte GA-5VMM Re: 430VX or 580 […]
Show full quote

sadly no diagram for that one, here a couple era appropriate ones including pretty close MVP4 Gigabyte GA-5VMM Re: 430VX or 580VPX schematics

Since you have another one narrowing it down seems doable. Im guessing you tried swapping bios chips and cpus.

>last code I see is 4F

at this point in time all the magical security/passwords were still stored in regular CMOS ram, thats inside South Bridge and since

> There was a tiny bit of corrosion on the South Bridge pins, but I cleaned them off, resoldered, and verified continuity.

I suspect there might be more hiding somewhere, under chips, under slots, under South Bridge itself, most insidious kind is eaten VIA - looks like a black dot inside via but in reality no connectivity to the other side

Excellent insight and suggestion. I'll remove the south bridge and see if there's any ruined vias underneath. Thank you!

Go to top of page Go to top of page
Back to General Old Hardware
Close window
Close window