shear_xear Posted October 17, 2019 Share Posted October 17, 2019 Hi everyone. I have an Atari 7800 that I added composite AV to, and now the 2600 games have weird color bars that show up. Pitfall is probably the worst. Any ideas what might be causing this? Thanks! Quote Link to comment Share on other sites More sharing options...
RevEng Posted October 19, 2019 Share Posted October 19, 2019 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. Quote Link to comment Share on other sites More sharing options...
shear_xear Posted October 20, 2019 Author Share Posted October 20, 2019 Ok. I know the TIA itself is good as I already put in a socket and replaced it with a known working TIA. I will look for any bridges and hopefully I can find something there. Thanks! Quote Link to comment Share on other sites More sharing options...
RevEng Posted October 20, 2019 Share Posted October 20, 2019 Yeah, I wasn't thinking bad TIA, so much as your mod placing more current demand on the 7805, leaving less for TIA. Quote Link to comment Share on other sites More sharing options...
shear_xear Posted October 20, 2019 Author Share Posted October 20, 2019 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? Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted October 21, 2019 Share Posted October 21, 2019 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. 1 Quote Link to comment Share on other sites More sharing options...
ABaffa Posted June 18, 2022 Share Posted June 18, 2022 Hi guys, I'm having this same behavior and don't have new clue of whats causing that. I tried everything and these blocks still appear on my screen. Have u find out how to fix it? best Augusto Baffa Quote Link to comment Share on other sites More sharing options...
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