Vertical adjustment and corruption?

[SlowCoder]

Ok guys and gals ...

 

I just got my hands on another 2600 4-switch. It's cleaned up, and when I turn it on with a known good game, it slowly scrolls vertically. I can see the game, but it appears corrupted and is unplayable.

 

I've cleaned the contacts multiple times, and verified the channel switch is on channel 3, same as my TV.

 

Ideas?

[SlowCoder]

Huh, not sure what the deal is, but I clicked the Edit button to update the initial post here, and when I tried to save, it told me I don't have permission to edit my own topic. Whatever ...

 

Anyway, I was trying to update it with more stuff I've tried ...

 

I've cleaned the contacts multiple times, both with alcohol and sand paper.

Verified the channel switch is on channel 3, same as my TV. As I see the video, this can't be the problem ...

Reseated the 3 mainboard chips.

Tried a different power supply.

 

The game loads, you can see animations, and it responds to game select and game reset switches, but doesn't appear to respond to joystick commands.

 

I doubt this could be a NTSC/PAL issue, as the game itself appears corrupted, not the video, except for the scrolling.

[Benzman66]

Try a different joystick. If it does the same thing, it is probably one of two things (or both).

1.Broken port

2.Bad chip

 

A bad port/cracked solder ring/etc would account for a joystick not moving in a certain direction if it is the same way on every joystick you try, but the same could go for a bad chip too. The scrolling issue definitely sounds like a chip issue. By swapping out the RIOT and middle (smaller) chips, should correct the issue, at least it has for me in the past.

Edited August 3, 2010 by Benzman66

[SlowCoder]

Try a different joystick. If it does the same thing, it is probably one of two things.

1.Broken port

2.Bad chip

 

I would think it is a bad chip as a bad port would not be giving you the scrolling issue on the screen.

Are you speaking of a particular chip? Which one would that be?

[Benzman66]

RIOT is the one closest to the game port, the middle one is the 10745 chip, and the bottom one is the TIA. I would swap out the RIOT first, then the 10745 next if no change. Make sure the notches on the chip line up with the while outline on the board.

[tetrode kink]

If the video problem is indeed caused by a bad chip, the TIA is way more likely to be the culprit. The TIA is the sole source of image generation, while the RIOT handles input and contains the console's whopping RAM stores.

 

-tet

[A.J. Franzman]

Huh, not sure what the deal is, but I clicked the Edit button to update the initial post here, and when I tried to save, it told me I don't have permission to edit my own topic.

You have one hour to edit your posts. If you get a paid membership, one of the many enhanced privileges that comes with it is extension of the edit deadline to one month.

[SlowCoder]

Yeah, you guys are awesome. I don't current have an extra Atari to pull chips on yet, but as soon as I do I'll give it a shot.