I'm installing a composite mod on a Rev 13 board, and having two issues - the image is really dark and some colours are missing.
Prior to the mod, on RF, the missing colours issue was present, but at least the intensity / brightness of the image was fine.
I've found that I can solve both problems - i.e. get an excellent image with all colours and good brightness - by piggybacking resistors (i.e. lowering reistance) on each of the three LUMA signals coming out of the TIA. I'm considering replacing the resistors with pots to be able to tweak it but that seems like a band-aid fix.
I'm referring to R214, R215, R216 (circled in the schematic below).
Anyway, I'm really curious about what's going on here, and if there's something else I should be checking that's the cause of the issue. I've done a ton of component testing and cleaning, verified the colour pot is good, voltages are good, etc. etc. etc. I also know the TIA and all other IC's are good (tested in another machine).
Thoughts????
(edited to clarify that I am piggybacking resistors, not adding resistance in series).
Full schematic here: https://www.atariage.com/2600/archives/schematics/Schematic_2600A_High.html
Prior to the mod, on RF, the missing colours issue was present, but at least the intensity / brightness of the image was fine.
I've found that I can solve both problems - i.e. get an excellent image with all colours and good brightness - by piggybacking resistors (i.e. lowering reistance) on each of the three LUMA signals coming out of the TIA. I'm considering replacing the resistors with pots to be able to tweak it but that seems like a band-aid fix.
I'm referring to R214, R215, R216 (circled in the schematic below).
Anyway, I'm really curious about what's going on here, and if there's something else I should be checking that's the cause of the issue. I've done a ton of component testing and cleaning, verified the colour pot is good, voltages are good, etc. etc. etc. I also know the TIA and all other IC's are good (tested in another machine).
Thoughts????
(edited to clarify that I am piggybacking resistors, not adding resistance in series).
Full schematic here: https://www.atariage.com/2600/archives/schematics/Schematic_2600A_High.html
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