I hardly dare to ask this, but have you tried rotating one IDE cable plug by roughly 180 degrees?

Cuttoon wrote on 2022-04-30, 12:14:

I hardly dare to ask this, but have you tried rotating one IDE cable plug by roughly 180 degrees?

Thanks for giving my question some thought!
I actually did. If connected the wrong way, most of the time the HDD won't even start spinning.
Also, given the fact that I can read the disc if I connect it after POST, it's safe to say it's connected properly.

can you try the following

486 + IO controller + IDE CDROM drive
try to boot from win98se install boot floppy (or any bootable floppy with cdrom support)

since most 486 won't have any idea about ide cdrom in bios, i'm just wondering if maybe the bios for you board is screwing something up during boot.

if on the other hand, with the ide cdrom attached you get similar behaviour as with a hard drive, then I'd guess something is screwy with the mainboard hardware. (though it could still be a bios issue)

Would be nice if you had a POST card.

octopus wrote on 2022-04-30, 12:39:

Cuttoon wrote on 2022-04-30, 12:14:

I hardly dare to ask this, but have you tried rotating one IDE cable plug by roughly 180 degrees?

Thanks for giving my question some thought!
I actually did. If connected the wrong way, most of the time the HDD won't even start spinning.

Yeah, well, our minds play silly tricks on us all, so I'd put that out there.
Also, never underestimates the levels of wanton noobery, noobdom and noobism than can be met here sometimes. 😜

octopus wrote on 2022-04-30, 12:39:

Also, given the fact that I can read the disc if I connect it after POST, it's safe to say it's connected properly.

OK, I had parsed through the whole post but must have missed that. Seems like a reasonable assumption, yes. 😉

weedeewee wrote on 2022-04-30, 12:45:

can you try the following […]
Show full quote

can you try the following

486 + IO controller + IDE CDROM drive
try to boot from win98se install boot floppy (or any bootable floppy with cdrom support)

since most 486 won't have any idea about ide cdrom in bios, i'm just wondering if maybe the bios for you board is screwing something up during boot.

if on the other hand, with the ide cdrom attached you get similar behaviour as with a hard drive, then I'd guess something is screwy with the mainboard hardware. (though it could still be a bios issue)

Would be nice if you had a POST card.

That is actually a great idea. So I've tried it: the results are exactly the same as when connecting a hard drive. That is: CD-ROM is Master. When connected before power on, the PC hangs on POST (blanc screen, no beeps, etc). When connected after POST, using the Win98 boot disk, the driver loads and I can use the CDROM.

So might be motherboard, might be BIOS.
Is there a way to troubleshoot this, other then finding another socket 3 motherboard?

Cuttoon wrote on 2022-04-30, 12:59:

Yeah, well, our minds play silly tricks on us all, so I'd put that out there.
Also, never underestimates the levels of wanton noobery, noobdom and noobism than can be met here sometimes. 😜

You are correct. After all these reboots it only now struck me that the date is messed up everytime. Battery must be dead, silly me.
Could a dead battery cause the issue?

octopus wrote on 2022-04-30, 13:35:

You are correct. After all these reboots it only now struck me that the date is messed up everytime. Battery must be dead, silly me.
Could a dead battery cause the issue?

We can only guess. Try it and let us know the results !

another option would be to find a board with a similar chipset and use the bios of that board in yours.

weedeewee wrote on 2022-04-30, 13:42:

octopus wrote on 2022-04-30, 13:35:

You are correct. After all these reboots it only now struck me that the date is messed up everytime. Battery must be dead, silly me.
Could a dead battery cause the issue?

We can only guess. Try it and let us know the results !

another option would be to find a board with a similar chipset and use the bios of that board in yours.

That's going to be a new project. The battery is soldered on and I have never replaced one of those.
Challenge accepted!

Edit:
Could be me, but it looks like there is no battery on this motherboard...
Am I missing something obvious?

Shame, somewhere on the way I must have fried my PSU. It's no longer working, fans not moving and just a soft electric hum.
Since I have no other AT case with a PSU, there is no way to continue with this 486 for now.
I'll get back to it when I get a replacement PSU.

too bad about the psu.
regarding the battery, it is already removed on your board. the silkscreen indicates it was next to the keyboard connector, ground closest to the keyboard connector
BUT!
Considering you've not shown the whole board in the photo, there is always a chance that there might be a chip similar to the DS12885 on there, in which case the battery is integrated onto that chip.

octopus wrote on 2022-05-06, 19:41:

Shame, somewhere on the way I must have fried my PSU. It's no longer working, fans not moving and just a soft electric hum.
Since I have no other AT case with a PSU, there is no way to continue with this 486 for now.
I'll get back to it when I get a replacement PSU.

I don't think the PSU is fried. That hum + the fan not turning on may be the protection kicking in due to a short circuit somewhere. Probably a tantalum capacitor on the board or the hard drive.

I would even guess it was related to your original problem. If you have a multimeter you can check for shorts before replacing the PSU, otherwise you may spend on a new one and may end up with the same issue.