Weird graphics problem with my 2600 Junior...

NERDtendo

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I got an Atari 2600 Junior in a trade a couple weeks ago. It was just the console, 26 games, and a 6 game switcher. I located a set of joysticks, a pair of paddles, an AC adapter, and I went to RadioShack and got a Phono Male to CoAx Female adapter for the video. I hooked it all up and turned it on and there is something up with the graphics. Turn on the console and half of the graphics are all smashed into the left side of the screen. Here is the wierdest part for me. If I hold the fire button down on my joystick controller, the graphics will correct itself (but of course the fire button is also continuously firing too). My joysticks aren't very good so I will need to look into a better set, but I don't think the joysticks are part of the problem as the graphics are like this whether a controller is in the port or not. Here are some pictures of what I am seeing...

While playing M*A*S*H...
MASHNoTouch.jpg


M*A*S*H while holding down the fire button...
MASHHoldingFire.jpg


Berzerk...
BerkerkNoTouch.jpg


Berzerk while holding the fire button...
BerkerkHoldingFire.jpg


I did open the system when I first got it (while I was waiting for the stuff I needed to play it) and cleaned the case and used a can of air to dust the inside.

I made an AtariAge account and posted the question there too. Anyone have any ideas of what could be wrong and how to fix this issue???
 
Try turning the system on with out a controller and see if that produces the same result. There are a few ram chips that do go bad but rarely do.

-Jake
 
Looks like a problem with the custom TIA chip.

The horizontal position of sprites is driven off internal counters in the TIA, synched to the clock from the CPU. 2600 has sprites for player 1 and 2, 2 missiles and a ball, and these sprites can be multiplexed vertically on the screen for more objects. The TIA also has latches to read the control ports.

Since not all sprites are being smooshed to the side, it could be a bad TIA. You can check the connections around the TIA pins 35 and 36 (player trigger inputs) for obvious shorts or problems eg with capacitors and check correct power (pin 1 is GND, pin 20 is +5V). If it's a bad TIA, then that 2600 is basically toast.

- James
 
Looks like a problem with the custom TIA chip.

The horizontal position of sprites is driven off internal counters in the TIA, synched to the clock from the CPU. 2600 has sprites for player 1 and 2, 2 missiles and a ball, and these sprites can be multiplexed vertically on the screen for more objects. The TIA also has latches to read the control ports.

Since not all sprites are being smooshed to the side, it could be a bad TIA. You can check the connections around the TIA pins 35 and 36 (player trigger inputs) for obvious shorts or problems eg with capacitors and check correct power (pin 1 is GND, pin 20 is +5V). If it's a bad TIA, then that 2600 is basically toast.

- James

Thanks that was the general conclusion over at AtariAge too.
 
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