Memory error troubleshooting (again) on the Compaq Portable III

I cannot catch a break trying to fix this stupid 201 memory error! Unfortunately this does not end the way I wanted it to, but at least I have closure.

This is part three (two and a half?) in a mini-series on the Compaq Portable III
You can watch previous parts here:

Bookmarks!
00:00:00 - Intro
00:03:22 - First problem found
00:08:46 - Testing round one
00:09:08 - Second problem found
00:12:10 - Testing round two
00:13:06 - Third problem found...
00:15:11 - Testing round three...
00:15:42 - What is going on....
00:20:21 - This must be it, right?
00:20:46 - Are you kidding me
00:25:18 - Chip testing
00:27:04 - Some time later
00:34:19 - Final testing! Really!
00:37:55 - Rusty parts swap
00:38:52 - Conclusion

Any feedback is welcome, as always.

Links!

Credits!
Music:
* White Drift - Bit Fight
* Molife - As Day Breaks
* Masaru Setsumaru - Data Select (from Sonic 3)
Putting up with my weird hobbies: My wife

Disclaimer!
I am NOT an expert, I have genuinely NO idea what I'm doing, and mostly just glue things together and use a lot of Google-fu until stuff works. I've been tinkering with electronics since I was a kid but have no formal training and will probably do things incorrectly. If you learn something from this, that's awesome, but trust me - I'm learning too!

#compaq #portable #repair

[TravellingVikings]

I admire your persistence in reverse engineering and working through the problems. Many would have given up a long time ago!. Although it wasn't a win for you, it's a win for us that have one of these as we can now be much better informed on how the memory bus is distributed around the board, perhaps saving us a lot of time.. I have restored one of these, but haven't restored the second one. The first one thankfully came alive after popping a few of it's caps. However it's powersupply died, so I had to reverse engineer that one to find the culprit, which I thankfully found and managed to fix. It's great to see how you have explained many of the issues you found..

[icedmuons]

Can't catch a break, brutal! I hate fixing problems that were already fixed... I feel you pain. I've got one of these too that I"m determined to restore, but it's a real slog!

[joeventura]

Whats the specs on that Tant cap you replaced because I believe I have the same problem, are there schematics anywhere for this board?