RASTER:Galaxian PCB Question

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Hello All :

I have a Galaxian board that is very close to working properly now - let me
explain what I've done and what is happening.

The board originally locked up with RAM errors and after socketing and
replacing the 2101's and the 74LS245's no more errors!

The board boots up normally with the crosshatch pattern and the moving
sprites and finishes up with OK in the middle of the screen. Then a low
"boop" sound is heard and the board resets. At this point it is stuck in
this resetting-loop.

What I've already done:

Just for good measure, I've replaced all the electrolytics on the board and
the D44VM4 transistor.
I've confirmed that my ROM board is OK with another working PCB board.
I've confirmed that my CPU is OK with another working PCB board.

Is there a good way to disable the watchdog circuit and if it is determined
that the problem is with that circuit how would I go about
diagnosing/repairing it?

Any information you could provide would be greatly appreciated.

Regards,

Steven Winslow

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Received on Wed Aug 28 23:06:21 2002