You should first remove that battery 😉

Post a picture of the whole board, I think there is good chance to find some documentation on the usual sites...
The front display has nothing to say as it is not connected to the settings on the board.

To hear the beep codes is a sign that the CPU is running, therefore the error should be somewhere else.

Tried with VGA installed?

1long, 3short No video card or bad video RAM Reseat or replace the video card.

http://www.bioscentral.com/beepcodes/awardbeep.htm

If I see right, the battery has already leaked and the acid is visible even inside on of the ISA slots. It might work, but I think there might be some damage beyond beyond repair.

Looks fairly close to an Abit PW4 of some kind.

https://th99.bl4ckb0x.de/m/S-T/35083.htm

c0keb0ttle wrote:

Looks fairly close to an Abit PW4 of some kind.

https://th99.bl4ckb0x.de/m/S-T/35083.htm

I reckon you're spot on - PW4 is silkscreened at top left corner of the pic.

PTherapist you'll need to set up the board using c0ke's link for a 486SX CPU, and for a 25MHz processor, as that's what yours is marked as.

Doesn't look like battery damage, as there's nothing damaged between the battery and the slot, probably just random corrosion.

JidaiGeki wrote:

Doesn't look like battery damage, as there's nothing damaged between the battery and the slot, probably just random corrosion.

No, that's almost certainly battery damage. Note the corrosion on the external battery pin header, neighboring jumper, and even the buffer IC just southwest of the BIOS EPROM.

What a shame, that looks like a nice board.

If it was a 30pin memory module you left in the motherboard the board won't work. 30pin memory modules use 8bit adressing and that's the reason for needing 4 sticks to get the 32bit memory the 486 uses.

I would reseat the RTC and BIOS chips (the socketed big ones close to the battery) as they probably have corrosion on their legs and see if that can make the motherboard come to life. In any case remove the battery, clean the board and use vinegar to neutralize the battery gunk. If the motherboard won't come to life get an ISA Port 80 post code indicator which could help you localize the issue, they are only a couple of $ with free shipping from China.

To me this motherboard looks totally slavable.

Wow thanks, I had a feeling somebody here would recognise it. It is indeed an Abit PW4. I didn't end up needing to change any jumper settings however, as I managed to find & straighten the pins on it's original CPU (which is an AMD Am486 DX4-100, not Intel as originally stated). But still very useful to know what board it is and it's settings etc, I have saved that page.

Oh and good spotting on the 25MHz CPU, I honestly never noticed that - I had 2 spare CPUs 1 of them was 33 so I didn't check and assumed they both were. I'd completely forgotten that I had that CPU overclocked to 33MHz in the PC that I took it from (a PC that is now running a faster clock 486 DX instead). 🤣

With the original CPU installed and also with testing several different Graphics Cards, the same issue. The beeping occurs with the 72-pin SIMMS installed. It doesn't beep at all with just the 30-pin SIMMs and also no POST either. I also tried replacing all the RAM with different chips from my collection, just to rule out faulty RAM sticks.

So I guess I'll have a go at the suggestions posted here at some point, re- cleaning and reseating the chips etc. This PC is in rather poor condition as it has been stored outside in a shed and been exposed to the damp conditions, as such it may have a lot more damage than just a leaking battery. I'll order one of those POST code analyzers also.

I haven't ruled out a faulty PSU either, so once it's cleaned up at some point, I may test it out with a different PSU just to make sure.

Thanks all for the help. 😎

Unfortunately, it's likely the leaking battery damaged a RAM trace or via under one of the SIMM sockets, the RTC chip, or that first ISA socket.