two-port 5200 video problem... help?

[TheDreadGazeebo]

I Picked up a boxed 5200 today from my local Salvation Army, It's in beautiful shape, but when I got it home and hooked it up, all I got was a garbled mess. Hoping someone can point me in the right direction, as I would really like to get this guy working. I have cleaned the pins on the console as well as my games with rubbing alcohol. I have it hooked up via one of these things, and am using the Atari brand power adapter that came with it. I have tried every possible combination of channels/switch positions too.

 

Here's what I usually get when I try to play some Pac-Man:

 

 

And here's what I get once in a blue moon if I wiggle the cartridge just right:

 

Any ideas what might be wrong here?

[0078265317]

Nice find, hope somebody can help. I always thought the 2 port was more stable. Zylon fixed my 4 port and since then no issies except once in a blue moon. Today I knocked the 4 port box slightly while playing jungle hunt just now and it went dead. It would not turn back on. I was so scared. Then I unplugged the box and all the connections and ac and reseated everything until I heard the click and it turned back on. What a relief. Not sure if the box has a fuse or what happened. I've done it once before but it always comes back on after a reset of the connections.

[zylon]

Looks like a possible RAM chip failure.

[TheDreadGazeebo]

thanks for the insight guys. I cracked the console open today and tried a different video cable. no dice. I pried the heat shield off, but now I have no idea what I am looking at. is there a replacement chip kit i can buy and just replace everything, or should I start looking for a parts console?

[FABombjoy]

The loss of horizontal sync / weird colors makes it look like the modulator is out of alignment. No advice to give as I've never adjusted the modulator on the 5200.

 

The service manual has a "Warped Ragged Picture Troubleshooting" section. It might be worth going through those tests.

[TheDreadGazeebo]

It seems those tests require an oscilloscope which I don't have access to. However, I noticed these two wires soldered to A15 and A27 on the board. I haven't seen anything like this online, is this a mod or repair, or something from the factory?

[0078265317]

Definitely weird. I hope somebody can help.

[zylon]

It seems those tests require an oscilloscope which I don't have access to. However, I noticed these two wires soldered to A15 and A27 on the board. I haven't seen anything like this online, is this a mod or repair, or something from the factory?

 

Not sure of the wire, but some systems had improvements or cost cutting measures taken. The row of 8 IC's right above that wire are where I'd look first. Those are the RAM and it looks like some have been changed out before.

2nd place I'd check would be the 4 largest IC's on the board.

[TheDreadGazeebo]

Should I just try swapping out each RAM chip one by one? I'm thinking of picking up a few of these which I found in another thread to try. Are those the correct replacements?

[zylon]

Should I just try swapping out each RAM chip one by one? I'm thinking of picking up a few of these which I found in another thread to try. Are those the correct replacements?

 

Not sure... The 5200 RAM is listed under custom IC's at Best Electronics so it may be different than the normal computers of the day. I'd have to go and look through my spare parts to see.

Best lists them at $1.50 each currently.

 

A couple ways of quick testing them is to feel if any get hot while running. A shorted IC will get very hot. (any that have MT as the brand should be replaced ASAP)

What I do is replace them one by one to find which ones are bad. I toss the bad ones and replace all 8 anyway. The leftover good ones I save for spares.

BTW: you may have more than one bad IC.

[TheDreadGazeebo]

awesome, thanks for the help. Going to test them out and order some replacements today. By MT do you mean Mostek? all 8 of my chips are made by them, guess I'll just order 8 of those IC's. Does Best Electronics have an order form somewhere, or do you have to e-mail them to place an order?

 

Edit: so I fired the console up with the case open and checked all of the RAM chips. none of them seemed to heat up at all, but the two largest IC's right below the cartridge slot got pretty warm. is this normal?

Edited November 11, 2014 by TheDreadGazeebo

[TheDreadGazeebo]

It's not letting me edit my post anymore for whatever reason, but I realized after posting that Best Electronics only takes orders by email. I sent them an email describing the problem, hopefully they can provide some insight. I'll report back here when they reply

[0078265317]

Also download this.

 

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CEUQFjAI&url=http%3A%2F%2Fwww.atariguide.com%2Fpdfs%2FAtari_5200_Field_Service_Manual.pdf&ei=tptiVMKWJYOlNtaTgegI&usg=AFQjCNEW6xyOti9lCyQQPTbXdR38sy0Y7w&sig2=lY0zZ2wR1h_Ikde736m1hw&bvm=bv.79189006,d.eXY

[zylon]

awesome, thanks for the help. Going to test them out and order some replacements today. By MT do you mean Mostek? all 8 of my chips are made by them, guess I'll just order 8 of those IC's. Does Best Electronics have an order form somewhere, or do you have to e-mail them to place an order?

 

Edit: so I fired the console up with the case open and checked all of the RAM chips. none of them seemed to heat up at all, but the two largest IC's right below the cartridge slot got pretty warm. is this normal?

 

None should get more than just warm. Another common culprit for graphic issues is the GTIA, which is lower right.

[TheDreadGazeebo]

None of the chips seemed to get excessively hot after 15 mins or so of the console being turned on, just warm as i would expect. I got a reply from Best Electronics, tried running a channel scan on two different tv's at their suggestion, and got nowhere. now I am convinced that I have a bad RF modulator.

[0078265317]

Any progress??

[kneehighspy]

is this a C021374 or C021376? i am refurbing a 5200 now and its a 21376, first i have ran into. is pin 11 of C014805-22 lifted?

 

all you need is an rf to composite adaptor to hook up the 2 port, the 4 port has the powered switchbox.

Edited November 18, 2014 by kneehighspy

[0078265317]

Any luck fixing this?

[0078265317]

Any progress. Or is this dead now.

[FABombjoy]

I had a chance to eyeball the 5200 modulator recently and there is a single adjustment on the side. I'd be curious if turning it clears up the OPs problems.

[ataridave]

Well, Combat Commando, now I know what's wrong with my 5200. Except, in my case, the 5200 freezes after a minute or so of game play. I don't have any kind of electrical or soldering skills at all, so I'll give it to my older brother, who will give it to a place that recycles electronics.

[atari-dna]

Probably just needed to tune the RF modulator. Can be done with a hex key 5/64. Preferably plastic, but you can use metal it is just harder to fine tune as it conducts and creates interference. Patience can get it done though.