Interesting Tempest Problem - Spikes are Whacked!

texasmame

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Interesting Tempest Problem - BOARDSET FOR SALE

******THIS BOARD IS SOLD********


Got a spare boardset back from the dead but it's left with a very odd problem that I can't find any examples of here or online.

All looks and acts normal except for these two things:

1. While your guy moves everywhere he's supposed to, the shots only come from a few select areas - in Level 9, for example, the 3 or 4 columns to the far left of the screen.
2. The spikes are all off - see the pic of level 9.

I know the monitor is good as I have a known good boardset in there and it's fine. Also, the Aux boards are both good, so it's an issue on the main spare PCB I have.

All the voltages are correct at the test points, reflowed the pins for the connector cable between the main and aux and reflowed the connector for the main board. Removed, reseated all chips, etc. - all the usual things.

All self-tests pass, too. All screens in self-test also look fine.

Any thoughts?

kcl4bd.jpg


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Your post made me triple check the board - all ICs going the right way but there is one transistor with one of the legs that was broken off. That HAS to be the problem but I no longer have a Tempest to check it. :(

FUUUUUUUUU. . .
 
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