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Andrud

2600 Graphical Issues - TIA/RIOT Issue?

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I recently purchased a 2600 Darth Vader at a yard sale. The unit was labeled ‘2600 Original Needs Work’. It was $15 so I decided to pick it up anyway. I fixed the first issue which was the power jack not making connection with the power cord end.

 

Now that the unit powers on, it displays incorrect graphics. From looking around on threads, it seems that this is an issue with one of the ICs. I am unable to get a clear answer if this is a bad TIA chip or RIOT chip. I would rather not buy both unless necessary.

 

post-61511-0-63335400-1501973742_thumb.jpg post-61511-0-57991000-1501973795_thumb.jpg post-61511-0-84981700-1501973818_thumb.jpg

 

Does this seem to jump out as a specific issue to anyone? Any help would be appreciated.

 

Symptoms:

Misplaced/distorted graphics

No (or very little?) sound

 

Related(?) Threads

https://atariage.com/forums/topic/263506-atari-2600-jr-bad-tia-or-riot/
https://atariage.com/forums/topic/240746-bad-tiariot-need-help/
http://atariage.com/forums/topic/181394-atari-2600-strange-video-problem/

https://www.youtube.com/watch?v=aAeXVazgUXc

In this video, the 2600 is having similar issues to mine. He troubleshoots it by swapping the ICs with a working machine, but I only have a working 2600jr with soldered ICs.

post-61511-0-06490000-1501973855_thumb.jpg

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I'm gonna say it's PROBABLY the TIA chip (furthest from the cartridge slot), but there's an outside shot it might be RIOT. I'd suggest you start with some of the simplest, early games for the system, since they rely on the TIA for nearly everything, with very few clever memory tricks. Combat, for instance, reflects the playfield around using internal TIA registers, and they generates the video signals to display the game. If even Combat looks fubar, it's almost certainly TIA.

 

Now having said all that, removing unsocketed IC's is a pain, especially if you're trying to save the chip just in case. Use lots of flux and a de-soldering iron and lots of patience. Install a socket when you've got the old chip out and the holes cleaned up well. That way you can replace chips again in the future if necessary with a lot less trouble!

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It looks like, based on the photo, your chips are socketed, correct? If so, you won't have to do any soldering or unsoldering. That's a big plus. I'm usually broke, so I understand not wanting to buy both chips. However, once you figure in shipping, it might be better to buy both at one time. There are probably some people here on the forums that have extras they might let you have cheap. You can post a thread in the "WANTED" section and see if anyone can help you out. I'd agree with DrVenkman about it probably being the TIA, but there's always a chance it isn't. If you're a gambler, the odds are in your favor that it's the TIA. ;)

 

Oh, Welcome to the forums! :-D

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These are, in fact, socketed ICs so they are easy to remove. I also removed, cleaned and re-seated the RIOT and TIA, but no change.

 

I broke out some earlier Atari games as recommended

 

post-61511-0-31050700-1502041430_thumb.jpg post-61511-0-29887400-1502041444_thumb.jpg

In combat all of the playfields seemed correct but the tank’s positions randomly changed and the blue tank spun around at the left side of the field.

 

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Space Invaders looks almost perfect, though vertical lines appeared sometimes. Bullets also seemed misplaced.

 

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Super Breakout has some misplacement as well.

 

If this is still looking to be a bad TIA then I’m going to order a replacement. I’ll post in “Wanted” like @RamrodHare mentioned, but I’ll get one from Best Electronics if I don’t get a hit after awhile.

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Yeah, I really think it's a TIA issue with the fubar graphics. Frankly it wouldn't hurt to have a spare RIOT or two. I've had two 4-switch Woodies with bad RIOT chips. so ...

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