Missing Green

[HappyCactus]

Hi,

I'm fixing a 2600AP, probably from Hong Kong, revision is unknown ("Rev" is visible but no number), dated Nov 30, 1982. I installed the single transistor "composite mod" circuit (with BC547 instead of 2n2222/2n3904), by removing Q201, L201, R222, R209, C209 and RF modulator as described. I changed the values of the bias resistors to 4k7 / 6k8 because the voltage levels were very low (around 400mV). Now the levels are pretty ok (I'm in doubt if adding a 100uF series capacitor to the output of the buffer stage). Tested with the diag cartridge v.2.6P. Seems acceptable.

But with Pitfall! the trees are blue instead of green. All games are same color, green seems pretty missing.

Tweaking with the color adjustment potentiometer doesn't seem to fix.

Any idea? Note we're talking about PAL version, Hong Kong -- Power capacitor is rotated (parallel to short side of the board) and the video buffers (A203) are missing.

 

Thanks in advance.

 

F.

[alex_79]

Are you using PAL games? PAL and NTSC TIA have different palettes, so if you mix games and consoles from different TV standards the colors will be messed up.

 

E.g. this is how the NTSC version of Pitfall! looks like on a PAL 2600 console:

[HappyCactus]

Hi Alex

Well... now that you mention it, I never considered this possibility. I don't remember where I bought it or if they are my original cartridge. So it might be possible they are indeed NTSC games. I need to further investigate. 

Thank you! That would explain a lot of things.

 

Federico