Repairing 2600 and Capacitor Question

[Aamp]

Hi! Finally after a long time looking, I found a 2600 for ten bucks! My Coleco and Atari Pinball console work on my T.V. and the 2600 hooks in the same way, so I know it's connected up right but when switched on, I could only get a black screen with wavy bits and fuzz. No games came up.

 

I read about bad chips and checking voltage across the 3 pin regulator. I had 4.8 volts but my power brick either due to problems with the system, age, fluke, something I did while in there, etc. it died while testing.. Power was getting to the system. I stopped trying after so I don't blow something up. I bought a 3rd party new adapter today and have not plugged it in again.

 

Inside, I saw this and wondered what this waxy looking stuff on the ceramic disc capacitor is. Is that some ooze from it? Anyone know?

 

 

Thank you!

[Aamp]

Looks like it's a varnish coating that was thick in that spot. It scraped off and has a rougher surface there. Plus I don't think there's ooze in this type of cap Going to clean the unit, maybe remove the shield to the chips to inspect and hopefully get this working. Since I'm new and couldn't find a way to edit my post, I'll let you know how it goes!

[ApolloBoy]

Ceramic caps don't have anything to "ooze" out so that isn't your problem. You might want to try replacing the 7805 anyway, or you can also try reseating all three major chips.

[shadow460]

First thing I'd do is clean the cartridge port. While you've got the system open, look for anything that might have spilled onto the motherboard and remove it. If there's stuff under the port, you will have to desolder it. Also look over the entire motherboard very carefully for cracked solder joints. It takes a while to re flow the entire board, but it's a pretty easy fix otherwise--if that's what the problem is.

 

Next step is to remove and test, or at least clean, all three ICs. If any are soldered down, you don't need to worry about them--yet. If something was spilled into the system, it's possible that it got into a socket and is preventing a good connection between the socket and the chip.

 

What you really need is a working system to test the ICs in. I'm thinking you're gonna find a fault with one of them, probably the CPU or the RIOT. A working console (or known good ICs) would tell you if one of those chips was bad, and it would tell you which one. You'd have to desolder the ICs for this.

 

I had a similar problem after having coffee spilled into a Vader. I had to remove all three sockets and solder the chips down to correct it. There was coffee on all of 'em and it had run down into the sockets as well. It was also under the cartridge port, so I had to unsolder that and clean the board up around it.

 

I assume you've checked it on both channel 2 and 3. Did you try it third party games only, or were there some Atari or Sears ones in the mix? Those tend to be a little more reliable due to the invincible dust covers they have in each cartridge.

 

If none of that works, it's probably got something wrong with the motherboard. In that case, save or sell the thing for parts.

Edited December 26, 2012 by shadow460

[Aamp]

Thanks guys. I was reading about that coffee spill. Good you got it cleaned up and fixed up. I was trying to remove the cartridge port until I read that it had to be desoldered so I'm glad I caught that, thanks! . I am thinking I might try to get a populated motherboard to put in its case since after reading here and around here, I do suspect it is one of the chips. The system does the same thing when hooked to the tv with, or without any chips with just a black screen, no 3rd party titles were tested.

 

Two of the pins are bridged with solder on the TIA which looked odd but I think both the pins are AUD 1 and 0, I am assuming audio. Everything looks in great shape otherwise, I also noticed a Vader with a busted casing on local classifieds that I could maybe use to make a working one without a broken case or to test chips? I have been searching for a 2600 for a while now so this seems like a tease lol but thankfully I at least ad the video pinball console to play afterwards which makes it less disappointing

[Aamp]

Is 4.8 volts acceptable output on the one side of the voltage regulator?

[yllawwally]

4.8v is generally not enough. That voltage will usually allow the atari to start but give weird video issues, such as rolling, fuzziness, and color problems. I would put a new regulator in, they're cheap and easily swapped.

[BigO]

If you're still getting just 4.8 volts with the new adapter plugged in, I'd echo the above advice to swap the regulator. That's a part that even Radio Shack stores still carried last time I checked. (not as cheap as other places, but convenient).

Edited December 28, 2012 by BigO

[Aamp]

Thanks guys. I went to The Source which used to be Radio Shack here and grabbed a 7805. I soldered it in and now get a solid reading of 5.0 but still just a black screen on the TV. I learned what the 3 pins on the regulator are now though which I didn't know before . And I found a dreamcast at the same thrift store for $10 so I'm playing that today.. Thanks again for the suggestions, glad I tried the regulator or I would have wondered.