Problems with my new 7800

[DamienC]

I just got a replacement 7800 (to replace the one that died) today in the mail. It works great with all my 7800 games, but my 2600 games play in black and white. Yellow seems to be the only color that appears. I tried a few carts (ROTJ: Death Star Battle, Mario Bros., and Snoopy and the Red Baron) and all were the same: mostly black & white, but yellow graphics were fine. Can anyone help?

[+Mitch]

Have you tried fiddling with the pause switch with a 2600 game on? The 7800 pause key is the old 2600 color/bw switch in disguise. It could be there is something screwed up with it.

 

Mitch

http://atari7800.atari.org

[DamienC]

Just tried that. No change.

[+Propane13]

If I remember right, there are 2 color potentiometers in the 7800-- one is for the 2600 color scheme, and the other is for the 7800 color scheme. It's possible that the 2600 one is out of whack.

 

Disassembly of the 7800 can be found on Mitch's site:

http://members.aol.com/~Atari7800games/Diagnostic.htm

It tells you which pot is the 7800 one, so I assume that the other is the 2600 color pot. I'm sure someone can verify for me.

 

I hope this is useful.

 

Thanks,

-John

[+-^CrossBow^-]

The top is the 7800 color pot...the bottom is the 2600 color pot. In essence we have two pot adjusters because we have two chips responsible for graphics. The TIA for the 2600 games...and the Maria for the 7800 games.

 

I have also seen dirty contacts in the 7800 itself cause a black and white screen. Not sure which one it is...but this was happening to mine. However, adjusting the color pots is the best idea first. However, I still haven't been able to get my 2600 colors to look quite right. I tried to use Krull on my actual 6 switcher to compare...but for some reason...I couldn't get the colors right on the 7800 still. Oh well, close enough is better than none at all. Let us know?!

 

[DamienC]

Well, I adjusted the pot and now all the colors are appearing fine. Thanks a lot for all the help, guys.