32-bit acorn hardware • Re: RiscPC - Blue screen [Post battery leak cleanup]

I rolled my sleeves up and have been doing my homework and testing as much as I can...

• Removed IC20 (CMOS RAM) gave it thorough clean and checked the pads individually for continuity, all buzz correctly, no damage I can see, I'm currently hanging off a loaned C2J Post connector based CMOS RAM bypass, but I think I could likely just place on a new CMOS RAM chip

• Removed RP16 (Fizzed like crazy, so still had acid present), cleaned underneath and soldered it back

• Moved on to testing all of the usual suspects RP16/IC33 etc along SK6, but to my surprise every track I've tested is still present, I'm not finished, but I'm getting quite far away from the battery now so it feels less likely to be a issue here?
  Screenshot 2024-07-26 110925.png

• I've been cleaning with a digital microscope scraping off any remnant green, mostly on SK6, a little in the back plane connector, there was acid underneath this (lots of fizzing) with distilled vinegar... A little worried there is something beneath here that's an issue too.

• I found some acid made it to IC13, not good (I presume it was placed on it's side for a time so it dripped down before I got it, I neutralised what I could and cleaned carefully, it hit around pin 120-160 to pin
  X1RHIj96Q7WBybLHpWdKIw.jpeg

• On the underside battery area (beneath the negative pole) there is this which has continuity with the exposed copper and between R130/R132[?] and C500[?] (Not sure which based on either missing markings, or me not quite reading the battery area correctly on the schematics):
  Screenshot 2024-07-26 114515.png
  Topside:
  pOS0eY8ET-ynIuMvgiEwAw.jpeg

• The resistors above SK6 show some light acid damage, but all continuity is there, the in-line resistor tests seem all good, the caps I think are okay
  byzbuBWWRCCiGQoGv84owA.jpeg

I now have Risc OS 3.7 and an ARM610 card, I get a consistent purple screen, I did get a grey screen once (almost a boot?), purple screen relies again on RAM so more weight that could be a problem area still, but the darker side is that the IO chip may not be working properly, I'm not good with an oscilloscope so I'm not sure how to test that. A purple screen is too early for a floppy POST code I think sadly.

Any advice pointers or thoughts welcome.

Statistics: Posted by Zaspath — Fri Jul 26, 2024 12:14 pm

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