Asteroids PCB repair help needed...

OK, I've got a couple of boards that are whacky and I'm not too sure the
best way to go about looking into them. Part of the problem is that right
now I have NO boards that do work (always easier to see if you have the same
thing in the same area on a working board). I'm looking for any advice on
how to proceed; here's what I have:

Asteroids board which high beeps constantly with no video. This high
beeping is exactly what happens when you remove the small PROM (usually
socketed) and boot a working game. The PROM (and socket that I added) check
out OK. I am thinking this is likley an addressing isse to that PROM and
that's where I am going to start.

Asteroids Deluxe board which displays a tiny (1 inch square) image in the
center of the screen. The image does not seem to be correct. I forget if
play mode works but I'm sure test mode does the tiny image thing.

Asteorids board with text OK but diagonals are whacky. The diagonals seemed
to be bloomed (but not the text) and also seem to be non-linerally distored
(i.e. cap problems). Caps are all present and OK. Play and test mode look
the same; fine but with diagonals distorted. The caveat on this one is that
it WAS working before I attempted to add a switchable speedup (the
leg-clip-and-lift mod). I have quadruple checked this work and it should
definitely be OK. I am thinking maybe I dinged something else without
realizing it.

Asteroids board that is blooming and has "shifted" text such that this
error:
2FF
shows up like this:
      F
   F
2
It also has a ROM error "2FF" that won't go away :> (I think I can lick that
one easily enough, though).

Asteroids board with no video at all; both channels are completely flat.
Replaced most of the final analog chips even though that was unlikely to be
the problem (because they are split channel at that point and I am most
likely looking at a single failure effecting both channels rather than 2
split channel failures). Other than no-video, it plays just fine.

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Received on Fri May 17 20:49:09 2002