luckybob wrote on 2024-04-01, 15:22:

If you had said P65UP5... I might have believed you.

Don´t mention it, I´m still searching for the PII CPU-card.

There is a part of me that wants to put that card into my p65up8, and then use some socket8/slot 1 adapters just for the giggles.

I really should do some tests with that card. see how Celeron chips work, etc.

majestyk wrote on 2024-04-01, 10:12:

After threading another wire through it the mainboard came alive again - after three years.

This was quite a journey...

Amazing work - congrats...

Thanks for the props!

Turned out the story wasn´t quite over yet. The IDE1 and IDE2 ports didn´t work.
There was an interrupted trace between "INTRQ" of the IDE1 connector and pin 83 of the PIIX (IRQ14).
On the second IDE port there was a corroded / broken trace between the "INTRQ" pin and a 22R resistor (array).
I think it´s just coincidence that in both cases the INTRQ line was affected.
Everything else seems to work for now, but I will continue testing...

Edit:
While testing all the PCI and ISA slots with different video and soundcards, due to the mechanical "stress" inserting and removing the cards, to original error reappeared. The via that I had repaired lost contact to the inbetween layer trace.
So I bridged the "OE#" input of the tri-state-buffer U16 with a wire to the "SOE#" output of the PIIX (pin 119). Now it´s all stable - again.
I had suspected this would happen, because I hardly got some solder into the totally corroded via the first time.

While everything runs stable now and I couldn´t find any further problems, I found a nice way to replace the original VARTA pest-barrel with a - more benign - 3.6V lithium cell.

To prevent the lithium cell from being "charged" by the onboard charging circuitry I had to "displace" R890 (510R) a little. This can be reverted anytime, if the original state should be desired.

Now I´m happy that this quite rare mainboard could be saved.

majestyk wrote on 2024-04-08, 07:38:

I found a nice way to replace the original VARTA pest-barrel with a - more benign - 3.6V lithium cell.

Anyone who owns an old Macintosh will tell you these are not so benign.... 🙁

Yea... those cells are even worse.

The upshot is, its easy to remove and slightly better voltage than a 2032.

So long as you remember to disarm the grenade before putting it back in storage....

I have a pair of Apple Quicksilvers since 2002 and the SAFT batteries are still fine. They had to be replaced once, though. Also replaced several in customer Macs - empty, but no damage.

A google search for "SAFT Lithium leakage" returns just pics of healthy cells.

What do these cells do?

well, its not the brand, persay.

But those 1/2 AA cells can just nuke a board: https://www.reddit.com/gallery/kpqaof

Maxell and Varta are the big offenders, but they all have a chance to leak over decades.

I dont trust any brand. I dont leave ANY battery in a computer once it goes to storage.

luckybob wrote on 2024-04-15, 20:16:

I dont trust any brand. I dont leave ANY battery in a computer once it goes to storage.

I support to strictly abide to this golden rule!

At least the 1/2 or 2/3 AA cells are easy to remove. I use them in cases when the mainboard clock refuses to run properly at 3V (CR2032), even after removing non-necessary diodes or replacing them by Schottkys.