Wrong colours on 2600

[naujoks]

I've revived a 6 switch 2600. It needed a new 6507, RIOT and TIA chip.

I also replaced the 2200uF cap and the 47uF caps, but not the "chicklet" caps yet.

I've also done the AV mod.

 

Games are playing find, but there's two problems:

Some, but not all, of the colours are wrong. Pink looks brown, for example.

 

On some games, such as Asteroids, when firing a shot, there some horizontal distortion to be seen.

 

Any ideas what might be the problem?

[+DrVenkman]

I'd suggest the distortion combined with bad color means one of two things:

 

1) You have a bad TIA chip; I've run across two bad ones in recent years with similar symptoms

2) Your modification/repair work has an issue such as a cap installed backwards, a solder blob shorting something, picking up the wrong signal(s) for whichever mod you're doing (*),  etc.

 

If it was just a color issue I'd suggest your color pot is dirty and/or out of adjustment but combined with the graphics corruption, that makes me think the color pot isn't the root of the problem.

 

Pics of your work plus the visual distortion might be helpful as well.

 

(*) The UAV for instance needs SYNC and three LUM signals from TIA, plus the COL colorburst signal. If you've got the LUM signals mixed up, that could cause color issues and possiby interfere with a clean video signal and give you some distortion.

 

[naujoks]

Thank you for your reply!

I fiddled around with the colour pot a bit, and that fixed not only the colours but also the weird distortion when pressing the fire button.

[+-^CrossBow^-]

The distortion when pressing the fire button I've seen come up before on AV modded 2600s. Most of them use the simple composite mod board and it seems to be a grounding issue of some sort? Haven't heard of this happening with other kits though.

 

[naujoks]

I used this AV mod:

https://www.thefuturewas8bit.com/deluxe-atari-composite-video-mod.html