Struggling with faulty socket 7 motherboard

[Glen M]

I've asked in every other corner of the internet so may as well ask here too!

I've been working on a faulty socket 7 motherboard I picked up from eBay a while back. This was one of those late night I really don't want this but screw it I'll stick an offer on anyway purchases. The board had (has) damage from its previous life with several pins damaged on one IC, 1 capacitor was completely removed from its legs and a few traces were badly damaged (1 cut the others partly cut). All this has been repaired but the board refuses to boot, refuses to do anything actually.

This is everything I have tried so far.

- I've tried a post card is both the ISA and PCI slots. On power up the card reports all voltages are correct. The reset briefly lights then goes out (so reset is working) then clock and frame LEDs light. No activity on the IRQ light and no post codes.
- I've tried 3 different socket 7 CPUs all with the same result.
- Power measures correctly around the board where I have been able to test, i.e. were I've found data sheets for and know what pins are VCC/VSS etc. Just the chipset to test in this regard.
- CPU is getting the correct 3.3v and is seemingly running, it certainly get hot quickly if powered without a heatsink (only for a few seconds)
- BIOS seems good. I've read it out on my EEPROM reader and even written a new one I found online but no difference in behaviour. Comparing the 2 ROMS they seem identical.

With there being absolutely no signs of life I'm drawing to the conclusion that the board is just dead either from further damage I can't see, possibly internal damage or perhaps one of the main chipset ICs are dead. There is a slight twist or warp to the board which I have been told could be an indication of internal damage.

If its dead then so be it but I'd like to if possible know for sure that its just not something silly that I've missed. It seems to be a rare board in so much as finding information about it online is almost impossible. The board is labelled AVB55C Rev B2.

Any advice for what else to check?

 

[TH2002]

Any signs of damaged/leaking capacitors? Leaking electrolytic fluid absolutely wreaks havoc on PC motherboards. Unfortunately many motherboards from this era do suffer leaky capacitors and unless caught VERY quickly, the internal traces can be irreversibly damaged by corrosion.

Could also be, as the warp in the board suggests, other physical damage to the board. If the board was originally in a case that could have been dropped, or if the board was stored by itself something heavy may have been set on top.

 

[kc8eyt]

You've probably already tried this, but move your RAM chips around into different slots. I once had a board I was ready to pitch but here to find out the RAM needed to be in the second slot to start with.

 

[Chuck(G)]

You probably already know about this, but I thought I'd point it out anyway. Has pages from the manual with jumper settings and a BIOS file. Material regarding most DFI boards tends to be easier to find than other brands.

 

[Glen M]

Many thanks for the replies folks and sorry for the lateness of this one.

Chuck(G), yes I found that site but those manual pages are actually for a slightly different board. I also have a few of the manual pages for my board but unfortunately no sign of life.
kc8eyt, I've tried ram in every slot and even none in an attempt to force an error but nothing.
TH2002, no signs of leaking caps but there is a fair amount of physical damage.

I've drawn the conclusion that this little board is beyond it. Started testing with the logic probe and there is absolutely no activity on any address lines or data lines around the BIOS. The test card in an ISA slot suggest reset is working but probing the reset pins on the likes of the BIOS or CPU they remain high so somethings not working and that I believe may be one of the main chipset ICs. I left power on for a while the other night while probing and noticed 1 of the ICs get hot, screaming hot very quickly. According to the data sheet this chip handles all IO functions so that may explain why there's no bus activity if its dead. I've just dumped the rom, saved what manual pages I have and retired the board to the display wall.

Since this board is relatively undocumented online is there any thoughts to where I can upload what information I have?