Bump.
Found this thing in my 'need to fix one day' box and found it to still be behaving as described before. Still don't have an oscilloscope, but I have a few other things - ISA and PCI clock measuring cards and Necroware's guide to de-lidding an in-place DS128(8)7 RTC to replace batteries.
That's the good news. Bad news is: didn't help:
- PCI clock is 25MHz (correct for jumper settings running CPU at 75MHz)
- ISA clock is 6.25MHz
- new battery is happily over 3V.
- still zero life in the board :'(
So I ruled out clock generation and RTC being the issue.
H.W.Necromancer wrote on 2024-02-03, 13:45:
Sorry for the necro-posing, but I am a Necromancer. 😀 Sad there are no more post how it went with this particular board. I can confirm the problem might have been in loose pins on the QFP chips. I had dead board of the same type and one chip (SIS 503) had almost left the board. The other one had some bad pins as well.
At first glance I couldn't see any issues, but one side of the 85C501 looked like it was a tiny bit short. Unfortunately I decided to put some flux on and quickly run over it with my soldering iron to be sure. Bad idea. I created two bridges while doing that and while trying to fix the second one I managed to break the leg entirely. It was pin 115, REQ 3 - pretty necessary for the PCI bus to work.
Given this I've decided to give up this board.