Atari 800 suddenly has no color

[bcostin]

I haven't had a chance to use my Atari 800 in a few weeks. I just hooked it up to my gaming TV via the RF output and, to my consternation, the display has no color. Everything seems to work correctly otherwise, it's just all in B&W.

 

I know it's not the TV. Unfortunately I don't have a composite video cable with the DIN connector, so I can't test the alternate video output. The RF cable on the original 800 is built in, rather than a jack, so I can't easily swap RF cables, either.

 

Has anyone else seen this happen? Any ideas?

[+rdemming]

I don't know about the 800 but the XL and XE series have inside a small potentiometer to regulate the color. There is a hole in the bottom in the XL/XE to adjust that potentiometer without opening the case.

I also had black/white output on my XL because of a bad contact in that potentiometer. But cleaning the contacts solved the problem.

 

Robert

[bcostin]

Thanks, rdemming, I found another reference to that adjustment via Google. I opened up my 800 last night and located the RF modulator, but I didn't see the adjustment pot nearby where I expected it to be.

 

I'm going to try cleaning the RCA jack mounted on the board (where the external cable connects), so I'll take a closer look for that potentiometer at the same time.

[A2600]

if anything tellme cause Im having the same problrm with my 520STfm

[bcostin]

Aha. I couldn't find the adjustment potentiometer on the mainboard because that's not where it is. It's actually on the back of the computer, behind a small hole in the metal frame that holds the RAM expansion and OS modules. Those clever little engineers. Oh well, I had to open up the case to fix a few sticky keys anyway.

 

The article archive on this web site helped me find the adjustment:

 

http://www.page6.org/issues/issue_08/Issue...are%20Facts.htm

 

Unfortunately adjusting the pot doesn't seem to have helped. I tweaked it a bit in both directions and the display is still in glorious monochrome. Maybe a faulty RF modulator? A bad chip? Evil spririts? I suppose it's time to buy a video cable and see if the composite output has the same problem...

[Callipygous]

It could be the GTIA chip. You could try reseating it. Gently pry it out and then push it back in. Oxidation prevents the pins from making good electrical contact and just the friction of removing and putting the chip back will fix them.

 

[edited]