Just to follow-up. I re-seated just about every cable. I still need to re-seat the cables that connect to the panel PCBs. I VERY carefully reseated the 2 flat foil cables on the right. I might try and do the wire repair to the cracked far right cable while I save up some cash for new membranes. So far the biggest mistake I made was not removing the batteries while reseating the RAM chips. According to Paul it may or may not have damaged them. No changes to the current problem is visible though.
My main problem seems to be that the computer has crashed.
I contacted Paul off list and asked a few questions while inquiring about the membranes. I wanted to post some of it here so that in the future newbs like myself can see it when they buy non-working boards. However, I am in this to learn as much as possible. A lot of it comes from the Service Manual.
Things to test first:
-re-seat all cables
-re-seat chips, without the batteries installed and after caps are drained (I read this elsewhere)
-measure output voltages: +5V REF and + 5 DIG are adjustable and should be adjusted within about 1%; +12V ANA, -12V ANA, -5V should be within 5%
-measure AC OK (about 5V) and DC OK (at least 2.5V)
-for the above tests all cables should be connected and power should be on; for a ground connection, attach meter to ground lug sticking up near where the power cables plug into the main board.
-measure power supply ripple at 60Hz and 120Hz using a scope to see if there is significant ripple...I'm still learning about this one.
-refer to schematics for other locations to test power supply voltages
I have been too busy with my home-remodeling to do most of this, but will hopefuly get to it soon. I ordered some leads for my scope and some DN5 DeOxit.