Well, since around the time we closed up our shop
(April of 1992) I've been
having to use a lighted magnifier to be able to see stuff that I was able to
deal with quite nicely before, I'm not up to it. Sucks, but there it is,
and I just deal with it.
I didn't necessarily mean that _you_ should do it. There must be other
people with that machine (amazingly, I don't own any CP/M luggables yet...)
You'd also need to remove some of the stuff from the assembly, which is
pretty tight.
And, shining a strong light through the boards to see where traces go etc. is
complicated by the fact that Zenith used blobs of hot glue to hold the
bulkier components in place, including a lot of the caps, TO220
transistors, etc.
I'd not do it that way. What I'd do is desolder any components that would
test as a short-circuit (fuses, low-value resistors, inductors,
transformers), and use a continuity tester to check where things go. I've
done this many times on monitors and PSUs and never had any problems.
Incidentally, if that glue is like the stuff we get in TV sets over here,
it goes conductive with age (!). It causes all sorts of interesting faults...
-tony