Picture goes black and white after a few minutes. Bad capacitor?

[Yoder]

Hey guys,

 

This is my first "real" post, and as usual, its about an issue :-) I'm a member over at Sega-16 a but I own almost every retro console, and of course, it all started back in the early 80s with the 2600 :-)

 

Anyways, I have an Atari 2600 that started doing this thing where after a couple of minutes I hear an "RF interference" sound and then I look over and the screen is black and white with some wavy lines on it. Restarting the Atari fixes it again, but only for a minute until it returns.

 

I'm wondering if I have a bad capacitor in there. If so, are there any that I should focus on? Or do I just need to change all of them?

 

Is this something you guys have seen? I have an NES that sort of does the same thing...thinking it's a bad cap too.

 

Thanks!

[zylon]

While that's possible, I'd check the voltage from the regulator before and after it screws up before anything else. That's where it all starts. Should be around +5 volts on third leg.

[Yoder]

While that's possible, I'd check the voltage from the regulator before and after it screws up before anything else. That's where it all starts. Should be around +5 volts on third leg.

 

Cool! That sounds like a good idea! Maybe I'll try it tonight yet :-)

[Yoder]

While that's possible, I'd check the voltage from the regulator before and after it screws up before anything else. That's where it all starts. Should be around +5 volts on third leg.

 

Cool! That sounds like a good idea! Maybe I'll try it tonight yet :-)

 

OK, I checked voltage in and out of the 7805 and it was 10.2V and 5V before and during the funky black and white screen. I also checked the big 2200 uF capacitor. I turned off the console and found that the voltage across the cap went up to 15 V and stayed there for a minute or so and was solid. Then I turned the switch to the "on" position and the cap slowly drained down over the next 30 seconds. I'm not sure if what I did made any sense or not, though :-)

 

The weird thing is that now it's taking much longer for the screen to go black and white...like 20 minutes whereas it was taking only a minute or two before.

 

I'll play with it more tomorrow night...

[Benzman66]

Replace that "green chicklet" looking capacitor near the power regulator. That should cure the problem. Most of the systems I have repaired over the years always needed one.

 

If it doesn't, then the next thing would be the IC chips or even a cold solder joint on the back of the B/W-color switch, but first be sure to spray some contact cleaner in the B/W-color switch and work it up and down a little, just to make sure no corrosion to save time.

Edited May 6, 2011 by Benzman66

[Yoder]

Replace that "green chicklet" looking capacitor near the power regulator. That should cure the problem. Most of the systems I have repaired over the years always needed one.

 

If it doesn't, then the next thing would be the IC chips or even a cold solder joint on the back of the B/W-color switch, but first be sure to spray some contact cleaner in the B/W-color switch and work it up and down a little, just to make sure no corrosion to save time.

 

OK, thanks. I'll take a look at that. One thing I've noticed is that the B/W picture I'm getting when it does this doesn't look the same as the "regular" B/W picture since it changes a little when I put the switch on B/W. Also the screen is full of wavy lines...like a moire effect.

 

I don't have a pic yet, but I get this sort of thing all over the screen:

 

[Benzman66]

 

Also the screen is full of wavy lines...like a moire effect.

 

I don't have a pic yet, but I get this sort of thing all over the screen:

 

 

I always use to say it looks like a huge thumbprint over the playfield.

[Yoder]

 

Also the screen is full of wavy lines...like a moire effect.

 

I don't have a pic yet, but I get this sort of thing all over the screen:

 

 

I always use to say it looks like a huge thumbprint over the playfield.

 

Yes that's exactly what it looks like :-)

 

Well, I had thought I narrowed something down to an issue with the power switch since it seemed flaky, especially when the screen got wavy (it seemed super sensitive then). So I opened it up and cleaned nasty tan gunk off everything. I now get a solid picture for 15 minutes or more (used to give me problems in 2- 5 minutes) but then it gets funky again...

 

I'll see if I can get the green capacitor at RS. I think it says 100V .22M and then there is an "F" a little bit lower. Is it a .22 microfarad cap?

 

This thread suggests that those are in six-switch 2600s and that mine is a .1 uF 24 V, but this one is a 4-switch Vader... Any thoughts on this? I'm thinking it's really a .22 uF based on what's printed on it...

 

http://www.atariage.com/forums/topic/62893-atari-2600-turning-bw/

[Benzman66]

Correct!

 

It depends I think on the day the board was assembled. I have seen small caps and large caps used in the wood and vader 4 switch models. The caps usually are printed 1K/100V, 104k/100V, 224/100V, etc.

 

I bought a crate of 224/100V and that is what I have been putting in each system I repair and never had an issue. You should be able to get them at Radio Shack. If not, I know Mouser Electronics does.

Edited May 7, 2011 by Benzman66

[zylon]

Jameco has them as well. (knock-on-wood) I've yet to replace one. Bound to sooner or later.

[Yoder]

Ok, cool. I thought so, so I bought a two-pack of them at Radio Shack today :-) They're the .22 uF ones and were $1.50. Hopefully I can put them in tomorrow if I get some time... This will be my first ever capacitor replacement :-) Then I have an NES with the same wavy lines issue, a Genesis with no audio, a Sega CD Model 1 with laser issues, and a Game Gear with back light issues. Each of these may need cap replacements unfortunately.

[zylon]

Ok, cool. I thought so, so I bought a two-pack of them at Radio Shack today :-) They're the .22 uF ones and were $1.50. Hopefully I can put them in tomorrow if I get some time... This will be my first ever capacitor replacement :-) Then I have an NES with the same wavy lines issue, a Genesis with no audio, a Sega CD Model 1 with laser issues, and a Game Gear with back light issues. Each of these may need cap replacements unfortunately.

For Game Gears, I'd recommend replacing almost every cap in it while you have it open. They were notorious for caps failing everywhere. The Majesco versions were slightly more reliable.

[Yoder]

For Game Gears, I'd recommend replacing almost every cap in it while you have it open. They were notorious for caps failing everywhere. The Majesco versions were slightly more reliable.

 

Yep, that's my plan. There is a guy in the UK that sells complete kits (and maybe even offers AA discounts IIRC). Not sure if I'll do that or try to piece together my own kits. I have one I bought and two others that the retro game place gave me (all with different issues), so maybe it would pay to just get an order from mouser, digikey, etc.

[Yoder]

OK, I changed the chiclet capacitor with a 100V .22 uF one from Radio Shack and I think it worked! It's been running for 45 min to an hour now and I haven't heard or seen anything unusual :-)

 

I'm not gonna close this case quite yet, but I think that may have done it :-)

 

Thanks for your help, guys! I probably would have started with the big 2000 uF capacitor if I had taken a wild guess.

 

Also resoldered the custom power cable for my 7800 that my two-year-old yanked apart :-/ I'll let him slide since he loves my Ataris :-)