Recapped Mac II with NUBUS issue

[blturner]

I replaced the SMD electrolytics with tantalum caps on this Macintosh II board 820-0228-A. The board boots, and sound is good, but the video appears with a scrambled pattern. I can see the cursor move between the broken up columns. I'm using a known good Macintosh Display Card with correct DIP switch settings. I've tried booting with known good RAM SIMMs pulled from working earlier revision Mac II boards. I did find a broken trace from D5 to B1, I bodged that with some wire and ensured continuity. Nearby the broken trace, UC7 was the worst-looking chip on the board with highly visible corrosion. I removed it to clean it up and reinstalled but the issue persists. Looking around the NUCHIP, nothing looks visibly awry. I've checked more traces but I'm running up against the limit of my abilities.

Any suggestions on further troubleshooting would be appreciated!

 

[Hugotronics]

To me UC7 is bad, you'll need to replace it.

 

[DevyDevly]

I share your pain @blturner with a Macintosh II with similar problems (820-0228-A)
Occasionally I get an all grey screen and a reset (NMI) also gives me half a sad Mac.
After a recap I've gone cross-eyed trying to find broken traces but only the one found so far (even with lots of candidates).
Half a sad Mac led me to think one of the ROMs was bad, but they seem good as far as I've tested thus far.
If I had spare (A)LS651 chips I'd probably try swapping in some news ones but they seem to be as rare as hen's teeth (and stupid expensive), unless I'm missing something.

If I manage to solve I'll post back here.

BTW - I do feel great shame at my messy work environment but my defense it's a small house and all I have is the kitchen table.