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Definitely check out the cable, too. It's pretty easy to check for track 0 sensor output directly from the drive, just using a logic probe. If it's not getting to the controller, it's almost certainly an interconnect problem.

Do we have a scan of the 8" adapter board, yet? Or is this one that someone laid out a version with an integral data separator?

Some interesting news. I walked away from the C3 for a while and when I booted it, it moved correctly. I let it go on, and it made some more noise and dropped me into an ‘Ok’ prompt, after giving an ERR #6, anything I typed gave an ERR #7 response. I set it aside for a while, and powered it up and booted it. Now I got an A* prompt. I never really got more out of it and after several boots, it went back to the juddering.

Hope to have a bit more time for it tomorrow.

The latest in the saga...

I changed the wiring of my B drive to match the A Drive and tried to get that working. I found out that the track zero sensor on that drive (b) was not working. I went back to using the original drive A. After a bit of board swapping I got to a configuration that was able to boot again. I was still using a fan on the boards to keep the system stable, so I thought I would simplify, and built out one of Glitch’s OSI-RAM boards. I took out the three 520 ram boards, installed the OSI-RAM and as only able to get an “H” when reset other than “H/D/M?”. I found an open solder joint on the OSI-RAM and reinstalled. Got the mem test loaded and running before it locked up.

Decided to work on the 510 CPU board, in case it was the problem. I had been checking temps of the chips but nothing was overly warm. I did use some freeze spray, but nothing seemed to be heat-related. I also most of the 6502-related chips and cleaned their pins just for good measure. I’m thinking of starting to substitute the chips off the CPU card to see if that works.

-Crawford