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Atari 2600 Game Select Problem


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#1 twiddler69 OFFLINE  

twiddler69

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Posted Thu Dec 6, 2018 2:36 PM

I picked up an Atari 2600 Six switch (heavy model) on Ebay cheap. Everything works except the game select is stuck in the cycle mode. I tried removing the switch but it's still stuck in game select. I tested the switch with a multimeter and it works fine. I tried removing all the chips and swapping them with another model but it still keeps cycling through the game modes. Any idea what might be causing this? I couldn't find any bad traces on the board or anything shorted. All the components look good and clean.



#2 chas10e OFFLINE  

chas10e

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Posted Thu Dec 6, 2018 6:06 PM

hmmmmmm does this happen on different game cartridges ?

 

I haven't encountered this yet and I hope this bump will get another member to chime in on what could be the culprit.

 

welcome to Atariage :)


Edited by chas10e, Thu Dec 6, 2018 6:07 PM.


#3 DrVenkman OFFLINE  

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Posted Thu Dec 6, 2018 6:14 PM

The console switches are read by the RIOT chip. Time to swap it out and test again. Good news is NOS RIOTs from early 00's production are available pretty cheap on eBay. Even better, all 6-switch systems are socketed so it's an easy swap. 



#4 twiddler69 OFFLINE  

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Posted Thu Dec 6, 2018 7:01 PM

It happens with any cartridge I try, I also did swap the RIOT chip with my Atari 2800 (Video Arcade II) and I get the same results, and the old RIOT chip worked fine on the 2800, so I don't think its a bad chip. I did this with all the socket chips with the same results. Perhaps its a bad ceramic disc capacitor? Everything visually looks fine.



#5 DrVenkman OFFLINE  

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Posted Thu Dec 6, 2018 7:10 PM

It happens with any cartridge I try, I also did swap the RIOT chip with my Atari 2800 (Video Arcade II) and I get the same results, and the old RIOT chip worked fine on the 2800, so I don't think its a bad chip. I did this with all the socket chips with the same results. Perhaps its a bad ceramic disc capacitor? Everything visually looks fine.

 

Those go bad pretty rarely, but anything's possible. It's also possible (and more likely in my experience) that you might have a bad socket - socket wipes can lose spring tension, can become dirty or corroded and in extreme cases completely break. I've run into that more often than bad ceramic caps (which I've never personally experienced). Given that you're having issues with a 6-switch, the most likely culprit to me is probably the ribbon cable between the two boards, or one of the connections on either end.

 

Anyway, if swapping chips didn't address the issue, what I would do in your circumstances is to open up the system and make some measurements with a logic probe (if available) or at least a multimeter as you try to cycle the switch, with a copy of the schematic handy while you do it. You'll figure out the issue pretty quickly. 



#6 twiddler69 OFFLINE  

twiddler69

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Posted Thu Dec 6, 2018 7:35 PM

I'll take a closer look at the sockets. I'll also check continuity on the ribbon cable.

 

Thanks






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