Video problems on 6 switch.

[boogieman!]

I recently dug out my 6 switch 2600. I plugged it in and it wouldn't output video signal correctly. I messed around a bit and figured out the first problem. The power jack had bad solder joints, it was floppy in the board. They two outer pins had come loose from the solder, I think it's called a cold joint.

 

I cleaned and resoldered the power jack. Upon further inspection, where the ribbon cable goes through the main board also had really bad joints, to the point some were wiggling around, again cold joint. I reflowed them.

 

I put in a clean cartridge and used a known good power supply and RF cable. The 2600 worked, the graphics showed up on my tv. I figured all was fixed. At this point, everything appeared to work perfectly.

 

Then the trouble started. I plugged a known good joystick in. As I plugged it in, the video went wonky. The colors seem correct, but the image is in horizontal bars. It's almost as if the image/video is squished and repeated about 5-6 times horizontally. There is no rolling or anything, it's rock steady, but just slices repeated. It does remind me of how it used to look when your TV needed adjusted to not roll the image from top to bottom. The vertical height on each slice is so small I can't tell if it's displaying the whole game screen X6 or just artifacts that are the correct color as the "intro" on the cartridge.

 

Has anyone ran into a similar problem? How can I go about diagnosing, testing, and fixing the problem? I have multimeter, and soldering ability. I've briefly scanned the "field guide" but seeing as how this was working but stopped when a controller was plugged in, I don't see any relevant info.

 

A side question, was solder different back then, or did some workers at atari just suck at soldering? Bad quality control?

 

 

[+DrVenkman]

To answer your last question first, QC back then was pretty good but of course there will always be outliers. I modded one of my 4-Switch Woodies a few months back and found that one of the pins for the 6532 RIOT chip socket had never been soldered at all - just flat missed during assembly. I got the system from the first owners, along with all their games and they evidently hadn't ever noticed any problems; go figure. In your case, the cold solder joints probably just occurred after years (decades!) of slight expansion/contraction cycles of the board from changes in temperature.

 

As for your video issue, since it started right when you inserted the joystick, you may very well have damaged something with static electricity. Later systems have diodes added to the joystick lines to prevent such problems. As for where to start diagnosing, you've already mentioned the Field Service Manual - that's the bible for system repairs. Check the symptom flowchart and see what it says. If you don't want to do that, you're stuck with some pretty rudimentary steps - measure the output of the voltage regulator; it should be right at +5VDC, give or take a tenth of a volt. Examine the board and see if any capacitors are suddenly leaking, if there are any burned spots on the board, etc. After that, it's chip swapping. Since you have a video issue, I'd suggest (in order of where I'd start replacing) TIA, 6507 and 6532 RIOT.

 

Good luck.

[AtariLeaf]

I didn't think hot swapping joysticks on a 2600 was an issue like it is with systems like the Colecovision but from my experience it can cause issues. I have a cap I have to replace because of an auto fire in my right joystick port and it could have taken the 4050 chip too (It didn't though). I now know to always turn the system off and even unplug it before switching controllers.