Atari 7800 showing no colour in 2600 mode! Help please...

Archived from groups: rec.games.video.classic (More info?)

Hi, my Atari 7800 is suddenly showing no colour when playing 2600
cartridges. (well, actually, it shows any Yellow sprites, but all the
rest are in greyscale --- like black and white).

However, all 7800 games play just fine - in full colour.

Any suggestions as to why this is happening and how to repair -- is
this a chip failure?

Archived from groups: rec.games.video.classic (More info?)

woodenflutes@yahoo.ca wrote in news:1114208932.319031.90930
@l41g2000cwc.googlegroups.com:

> Hi, my Atari 7800 is suddenly showing no colour when playing 2600
> cartridges. (well, actually, it shows any Yellow sprites, but all the
> rest are in greyscale --- like black and white).
>
> However, all 7800 games play just fine - in full colour.
>
> Any suggestions as to why this is happening and how to repair -- is
> this a chip failure?
>
>

Try the pause button. It functions as the B&W switch on a 7800. If that
doesn't work, dunno. 8*)


--
___
Chuck Whitby - Founder
East Coast Gaming Expo
http://www.ecgx.com
"It's the games"

Archived from groups: rec.games.video.classic (More info?)

> It's possible the color pot may need to be tweaked a bit. I'd
suggest
> you go to www.atariage.com and look for the 7800 forum to see if
> anyone posted a similiar question or you can post your question
there.

I've fixed it. It was indeed a bad connection either with the colour
pot or a short circuit on the motherboard around the colour pot. It
seems that over the years the gentle flexing the 7800 motherboard
receives when cartridges are inserted and removed can cause this sort
of problem on the motherboard. I re-heated all the contacts on the
motherboard with a soldering iron and turned the pot a few times with a
screwdriver to help remove any internal oxidization. It works fine
now.

You could tell it was a bad contact problem because if you pressed on
the top of the RF shielding with medium pressure while the system was
turned on, the colour would intermittently go to black and white and
back (with yellow remaining as the only constant).

Thanks for all of your suggestions.

PS: my usenet searching indicated other people have had this problem
too (with 2600 games playing in B&W). So it's nice to know it's a
relatively easy fix.