MCR II issue

I think I have my PS in the Tron squared away now. Battery damage
cleaned up, pots/traces/plugs replaced. The cab itself powers up, all
lights come on and such. I'm getting good 5/12V off the supply...right
up until I attach the game boards.

Once the logic is connected, the 5V tanks, reading about .23V on my
meter. This appears to be an issue with a short somewhere and I think I
have tracked it down to the VidGen PCB. At the 5V contacts (J1 2-5 on
the SuperCPU), the meter reads a short when the MCRII is connected, but
otherwise when the board is not connected. (They show typical cap
behavior: start as shorts, slowly increase in value as the caps charge
to meter voltage level.)

Firstly, am I way off track in thinking my problem lies here? Secondly,
any known failures in the MCRII that would lead to this kind of hard
short between the 5V and GND? If not, any ideas of what to look at?
Would Peter's favorite culprits, the sockets cause this kind of behavior?

On a side note, where would be a good place to find a
substitute/replacement for the busses (frequency shields) on the
boards? These are the upright metal strips that run across the boards
in a couple locations. They appear to be busses for the +5 and GND
planes, two metal strips, isolated from each other, but "stuck" together
and covered in paper. They look to "touch down" at various points
along their length, but some legs come from the "front" where others
from the "back." (Hence why I believe they are isolated from each
other.) Some of the legs have broken from flexing/age.

I apologize if this is basic, but I have almost no experience at
real-world trouble shooting, only book knowledge from my classes, so I
could easily be entirely wrong in where I am looking. I have not
replaced all the sockets in the stack, though I did replace the ribbon
connectors. Given my lack of experience, I am trying to limit what I
shotgun, for concerns of causing more problems with my re/work.
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Received on Tue Oct 23 13:13:21 2007