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Atari 2600 - strange video problem


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#1 Amstari OFFLINE  

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Posted Tue May 3, 2011 4:54 AM

Hi Everyone, I posted this in the hardware section but I haven't had any replies yet. Hopefully someone here can help!


I've got a strange problem with an Atari 2600 Jr with the Longhorn AV mod.

This is what happens with Space Invaders.

Posted Image

This is what happens with the Harmony Cart.

Posted Image

Both carts work fine on another console.

Has anyone seen this problem before? I purchased the console with the mod already installed and it has been working perfectly until yesterday.

Any advice would be appreciated. I have some broken consoles that I can take parts from to fix it.

#2 Benzman66 OFFLINE  

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Posted Tue May 3, 2011 1:34 PM

I would think it is an IC chip issue, but unfortunately most Jr boards have the chips soldered in instead of socketed, so it is going to be a little harder and more time consuming swapping them out.

#3 zylon OFFLINE  

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Posted Tue May 3, 2011 1:41 PM

I'd 2nd the IC problem, but I'd double check my connections to the chip first. One might've bridged.

#4 Amstari OFFLINE  

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Posted Sat May 7, 2011 6:09 PM

Thanks for the advice Benzman66 and zylon.

I'm going to try uninstalling the AV mod and see if I have the same problem before I start removing any IC chips.

If I still have problem which IC would you recommend I replace first?

#5 Benzman66 OFFLINE  

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Posted Sat May 7, 2011 7:05 PM

That is a hard one, as I have seen all three cause strange video issues. I would go with the RIOT chip first. That is the chip with 10750 printed on it and closest to the cart slot. Watch how you take it out and make sure the notch on the end of the chip is lined up the same way with the new chip when you put it back in. You may want to think about getting a socket at RS or Mouser and install that first. It will save you the hassle of soldering the chip if ever needing replaced in the future.

#6 zylon OFFLINE  

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Posted Sat May 7, 2011 7:38 PM

That looks like RIOT failure to me. In cases like that, it becomes a question of time+effort versus another console.

Edited by zylon, Sat May 7, 2011 7:41 PM.


#7 Amstari OFFLINE  

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Posted Sat Jul 16, 2011 11:24 PM

I finally decided to remove the AV Mod from the faulty Atari 2600 Jr. I haven't tried this console with RF yet but will report the results when I do.

Instead I put the AV Mod into a Light Sixer that has always had problems since I got it.

The original problem with the light sixer was that the picture was very snowy and the sound was almost all static, you could barely hear the game sounds. The picture seemed to get worse when sound played in a game too.

I installed the AV Mod and now it has perfect sound and a clear picture however the colors white and yellow are reversed. I've tried adjusting the color pot but it doesn't correct the problem.

Has anyone seen this problem before?

#8 Mark T OFFLINE  

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Posted Thu Jul 21, 2011 12:37 PM

I haven't seen that problem before with reversed colors...check out my thread on adjusting the pot effectively...hope it helps for you!


http://www.atariage...._1#entry2326952


Also fix the following component on the switchboard might help:
Green Capacitor: 224k Ohm 100v Capacitor
Fixes fuzzy video problems.

Edited by Mark T, Thu Jul 21, 2011 12:42 PM.


#9 Amstari OFFLINE  

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Posted Fri Jul 22, 2011 7:37 AM

I haven't seen that problem before with reversed colors...check out my thread on adjusting the pot effectively...hope it helps for you!


http://www.atariage...._1#entry2326952


Also fix the following component on the switchboard might help:
Green Capacitor: 224k Ohm 100v Capacitor
Fixes fuzzy video problems.


Thanks Mark. I had checked out your thread and I originally thought that is was just a pot adjustment issue but it didn't fix it.

I don't have any fuzz since installing the AV Mod but I might try replacing the capacitor anyway.

Fortunately I've got another Atari 2600 (PAL) that works fine but it doesn't have a mod. However I would like to get the light 6er working because it is NTSC and then I can play NTSC games with the correct colors.

#10 Mark T OFFLINE  

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Posted Fri Jul 22, 2011 9:10 AM

Amstari: Indeed! Good luck with fixing it…I might post my problem I had last weekend with the Heavy 6-switcher I bought from Ax and see if ppl on here might know what’s going on with it.

Have you tried replacing the chips?

#11 Amstari OFFLINE  

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Posted Fri Jul 22, 2011 9:23 AM

Have you tried replacing the chips?


Not yet. The only consoles I've got for spare parts is two Atari 2600 Jrs. So it would a pain to remove the chips from them, I might have to order some replacement chips.

#12 Amstari OFFLINE  

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Posted Sat Jul 30, 2011 7:50 AM

I've decided I'm going to try replacing chips starting with the TIA.

Should I get one from Best Electronics or is there anyone on Atari Age selling them?

#13 Deteacher OFFLINE  

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Posted Sat Jul 30, 2011 10:06 AM

I'll jump onboard the RIOT train on this one. I remember having a similar issue back in the day, when you would actually send the consoles away for repair. That space invader pic looks familiar to me. We could actually start up a game, but the invaders wouldn't speed up as you eliminated them. Even if there was only one invader left, it was still going at the first slow speed. Turned out the RIOT was bad. We sent it away, they fixed it and sent it back and we were good to go!

#14 Amstari OFFLINE  

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Posted Sun Apr 22, 2012 12:45 AM

It's been a long time since I tried to fix this but I gave it another try. I tried replacing the RIOT chip but I had no luck.

I've given up on the NTSC console for now and I want to put the AV Mod into a PAL Vader.

Is it possible to install Longhorne AV mod in a PAL console? I know it is designed for NTSC but can I just connect it to different pins on the TIA?

#15 Mark T OFFLINE  

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Posted Mon Apr 23, 2012 6:19 AM

A PAL mod is in the works!

http://www.atariage....d/page__st__150




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