A little Asteroids Board Repair help.... please...

I've got a real strange Asteroids Board that I'm trying to repair that got me baffled. Here's the scoop, if anyone has any opinions please let me know.

The boardset is a Rev 4, running on the bench.

The board works fine in self test, perfect picture, no errors are reported. In game play mode, the board watchdogs. In test all switches beep fine, including Tilt.

If you disable the watchdog, the game still does not run, only a diagonal line/outline of screen scrolls on screen.

Fluke 9010 unit verifies RAM OK (long Ram test)

Fluke 9010 unit verifies ALL ROMS checksum ok, in socket. (Also using a know good set, Rev 2)

Manually loading Vector memory with code to generate a + sign, works fine, and upon a DMAGO, you get a perfect +. All scope sig's that I have for the + match just fine.

For Kicks, Isolating the L6-Pin1, does indeed put the game into play mode, but obviously, you get no screen, restoring the connection results in watchdog's.

I've poked around in the VSM and TIMER for 2 days now, and in Test mode, everything looks fine.

Any suggestions ?

TomW

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Received on Tue Oct 31 09:50:15 2000