[Coco] 26-3024 MPI Blues...

[Rogelio Perea]

Aftera sting of CoCo (F board) lockups while having the 3024 MPI connected
(8709311 REV C board), I decided to open it up and troubleshoot it a bit
deeper. Previous attempts just by cleaning the connector contacts on the
MPI did not resolve.

The CoCo will run for about 1 minute or so with no problem and then lock
up, moving the 26-3029 floppy controller intto the CoCo works with no
issues at all.

First thing checked is the power supply, all voltages read ok except the
+12vdc which is actually a steady 11.8, don't think that would cause any
trouble at all as noted above, the 5vdc an -12vdc supplies a steady
nominal. Temp probed all ICs and power resistors, nothing that could be
overheating.

Next thing is scoping the power supplies for any bad filtering, beyond that
I am at a loss without going all logic-probe on the MPI...

Just throwing it out there, maybe someone has an idea on where to go next.
Have a new MPI coming my way, still would like to revive the one with the
problem.


-- RP