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2600 games with color artifacts after composite mod


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The artifacts look to be aligned with playfield and seem to be playfield bit-width, so it doesn't look like interference to me, so much as the TIA chip having trouble. I'd check your connections to TIA to ensure there aren't any bridges, however slight. If they look good, the next thing I'd suspect is TIA not getting enough current.

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2 hours ago, shear_xear said:

Ok.  It’s odd that this one 7800 would display that problem when none of the others have in the past.  Is it possible the 7805 is failing and may need replacement?

Maybe. It should be easy to check - just take the case off, power on the board with a cart inserted and measure the output voltage (pin 3 of the 7805), then Vcc of each main chip (for SALLY, that's pin 8; for TIA it's pin 20; for MARIA it's pin 25). If it's significantly less than 5.0VDC, you've possibly got a bad voltage regulator or power supply, or you may have a short on the board somewhere.

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  • 2 years later...

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