Space Duel #2 prob

Well I have another odd one. I have a SD pcb that I
had marked as not working, but all 74ls's checked (all
the ones I can with comparator).

Hooked it up to me test bench setup and it actually
worked...but noisy..I swapped in an aftermarket avg,
and nothing came up..put back in original and it
worked..odd..
The vectors were a little jumpy so I took it to my SD
machine and hooked it up. It came up but the screen
was adjusted far to large so most objects started
outside the screen..played a second or two then
switched on test. Test works, but nothing on screen.
Switch back and now nothing on screen but it plays
blind. Explosions also sounded like they were
distorted and there was a buzzing sort of sound in
speakers like a small short almost.

-took it back to test bench and now it would not come
up at all (may be blind but I do not have coin or
start or speakers hooked on bench) on screen.

-change the 15v regulators to new ones.

*game is on free play 1 player only so comes up with
two boxes over eachother for your choices.

-game now comes up on screen, but is about half the
size it should be in center of screen and what it
was before..nothing was adjusted.. adjusting pots to
max does little to nothing.

-I also change out a sound amp (solves the sound issue
I find later)

-IF I put on an aftermarket AVG, half the vectors
dissappear in time with the flashing of the player
boxes, and half remain. I put back on the original avg
chip, and it looks fine but the whole screen sort of
slightly goes larger and smaller repeatedly almost at
the same speed the boxes flash when you chose a
game..but it very noticeable..maybe and 1/8 of an inch
or so of movement.

So I take the pcb and go to my actual cab, and put it
in. With both avg styles, I get nothing on the screen
in either game or test mode, but it plays blind fine.

I took it back to test bench and the one
player/freeplay screen is still there but pulsating
like before. I switch dipswitches to regular attract
and it comes up, but pulsates..

-put in aftermarket avg and it goes to attract, but
there are vectors flashing all over the place.

any ideas???

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Received on Wed Oct 17 21:04:48 2007