Sure someone will find better, but these pages might at least get you started

https://skylots.org/6515394744/Instrukciya-MB … -AVB55C-EDO-SDR

https://www.elhvb.com/mboards/ask/avx55c/AVX55C.html

PC Hoarder Patrol wrote on 2021-01-22, 21:57:

Sure someone will find better, but these pages might at least get you started

https://skylots.org/6515394744/Instrukciya-MB … -AVB55C-EDO-SDR

Yes ! Your found layout matches the jumpers very well. Repo Man11 your jumpers are different than the picture.

Unite wrote on 2021-01-22, 20:57:

Any help would be greatly appreciated.

Missing the Heatsinks off the V regs. I would not power it up until you find some and focus on the the V reg on left side of board, that V reg appears to be the main 3.3v CPU reg.
The one on right appears to be the 2.8, 3.0, 3.2 v for MMX etc if I read the traces proper.
Once you get heatsinks test with standard 3.3v P75-133 or similar and not a MMX or AMD cpu.
Will go archive searching later when I have more time....

Added: is similar to one of Micronics boards.. The heatsink needs Mica back washer and non conducting bolt thru as you could short the V reg tranny's if bolted together thru a aluminum heatsink. Just an observation.

Horun wrote on 2021-01-23, 02:46:

Yes ! Your found layout matches the jumpers very well. Repo Man11 your jumpers are different than the picture. […]
Show full quote

PC Hoarder Patrol wrote on 2021-01-22, 21:57:

Sure someone will find better, but these pages might at least get you started

https://skylots.org/6515394744/Instrukciya-MB … -AVB55C-EDO-SDR

Yes ! Your found layout matches the jumpers very well. Repo Man11 your jumpers are different than the picture.

Unite wrote on 2021-01-22, 20:57:

Any help would be greatly appreciated.

Missing the Heatsinks off the V regs. I would not power it up until you find some and focus on the the V reg on left side of board, that V reg appears to be the main 3.3v CPU reg.
The one on right appears to be the 2.8, 3.0, 3.2 v for MMX etc if I read the traces proper.
Once you get heatsinks test with standard 3.3v P75-133 or similar and not a MMX or AMD cpu.
Will go archive searching later when I have more time....

Added: is similar to one of Micronics boards.. The heatsink needs Mica back washer and non conducting bolt thru as you could short the V reg tranny's if bolted together thru a aluminum heatsink. Just an observation.

The page I linked to clearly states that it's for an AVX55, but the BIOS that is downloadable on that page is for the AVB55.

Repo Man11 wrote on 2021-01-23, 03:16:

Unite wrote on 2021-01-22, 20:57:

Any help would be greatly appreciated.

The page I linked to clearly states that it's for an AVX55, but the BIOS that is downloadable on that page is for the AVB55.

Well yes I saw that but you never said anything in your post with the link about the manual being wrong but it could be the proper BIOS file.
You assumed the OP could figure it out and probably could but would it have hurt to include a comment about the manual being wrong but possibly the BIOS is proper?
Specially since he already found a link to a BIOS file. Jualready found a link to a BIOS file. Just my opinion and sorry if I offended you but do believe the more info you include in a post the less questions later....

Well I've tried everything and it seems the board is dead.

I appreciate its not best practise to power up the board with no heatsinks on the regulators but even just for 10 seconds there is absolutely no signs of life. No beeps from the speaker and no picture from either an ISA or PCI graphics adapter. The only socket 7 CPUs I have are a Pentium 200 and a Cyrix 166. Both are the same result, just dead.

There was significant damage on the board. On the chip bottom right (labelled PCI set) several of the pins (bottom right) were badly twisted with 2 broken off. I've repaired this to the best of my ability, its all reconnected again with no shorts anyway. Where the blue cap is now adjacent to that chip the former cap was ripped off with only the legs remaining. There was no signs of further damage though around this area. I also found 4 broken traces on the underside all of which have been repaired along with 1 on the top side.

I suppose this old board is just to far gone. It obviously wasn't looked after so perhaps there is just further damage I haven't seen or maybe the chipset or something else on there is just dead.

The next step would be to start following signals around the board but to be honest thats going over my head. Physical damage I can deal with, when it comes to the logic side of things, I get lost quickly.

I'm not sure I have ever seen one of these in existance even.

If you can't get it fixed, at least make sure it gets to someone that can/wants to fix it. We may even get a bios dump from it. Once I get to ASK of Hongkong, the picture will be added to UH19.

Have you checked if the VRMs output the proper (or any) voltage? Also, the BIOS could be corrupted, do you have the means to dump the content of the flash chip?

Agree ! ^ Agree ! ^^
Have you tried a post diagnostic card to see if there is any activity ?

Thanks for the tips folks. Checked the voltages and all 4 are outputting 3.38v but never thought to check my post card. Will do that later when I get a chance. I have dumped the BIOS and well, there is stuff on it. Not really sure what I'm looking at though. I should probably try comparing it to that bios in the link above.

If it interests anyone I run a small youtube channel and this board is the subject of this weeks video. Just so you can see the extent of work carried out so far and not intended as self promotion as I don't really go in for that. https://youtu.be/gzLOY8KUGyc

Tested with the diagnostic card.

All power leds are lit OK the reset lights for a split second so that's working then it just sits with the clk and frame leds lit. No post codes.

Not sure what frame means but seems to me as if the system is booting it's just not reading code from the bios.

Tried the bios rom from the link above and behaviour is just the same, infact looking through the rom from the link and the original one they seem identical.

Voltages all seem fine around the board and the voltage to the CPU is fine.

Any ideas for what to try next?

I saw your video earlier and it reminded me of a 386 board I have. It too has some leg damage on the chipset and although I have tried to fix a few it will still only post if I put a fair bit of pressure down on the chip.

I'm about ready to give up.

I think last ditch effort would be a complete reflow but I'd say that's unlikely to fix anything. The faulty presumably lies in the chip set and as such I think the only thing left for this board is to pick its space on my graveyard wall.

Try with a SIMM in slot 1 and 3 or 2 and 4 (so one open space in between). I seem to remember something weird about this board.
I may have owned an 430FX variant of it at some time.

evasive wrote on 2021-01-25, 22:17:

Try with a SIMM in slot 1 and 3 or 2 and 4 (so one open space in between). I seem to remember something weird about this board.
I may have owned an 430FX variant of it at some time.

Wow, just noticed after you posted this that the SIMM slots are numbered that way (0-1-0-1) on the board. Never even noticed, Good Job !

The last time I saw that board was 10 years ago. I was striking me as odd, hence I remembered. Now the wait is: will it boot with memory in slot 1&3 or 2&4...