Paddle Jitters..........hey doctor!

[SoundGammon]

I was going through some service info from Atari back in the day and reading service bulletins.

 

One mentioned a fix for paddle jitters and that it was caused by ripple on the power supply going to the pokey chip.

 

The fix was simple: solder a 10uf 16volt capacitor right on the power pins on the pokey chip!

 

Pins 1 - gnd / neg and 17 5V + positive!

 

Makes me wonder if it would help the 2600 and doing the same thing on the RIOT chip!

 

 

[+-^CrossBow^-]

It could, but honestly the reason these paddles jitter is simple due to time and corrosion build up on the wiper and crud building up on the carbon pad inside the pots. A good spritz of some de-ox-it or other similar cleaner and actuating the pot fully in both directions about 20x and they are pretty much good as new again. Don't even have to take them apart as I used to do nearly 20 years ago.

 

Also get a syringe of di-electric grease to fill the pot with and that will keep it lubed and help prevent oxidation from building back up again as quickly once it is cleaned.

Edited April 4, 2019 by -^Cro§Bow^-

[BigO]

I suppose it would depend on the jitter being observed. I can see how ripple that's not in sync with the sampling frequency could cause the paddle input to vary with no actual change in resistance, but I wouldn't expect it to amount to much.

 

I haven't noticed that happening on the 2600. If you're seeing that on the 2600, I don't see much harm on trying it. I guess if there's substantial resistance between the power supply and the chip somewhere this could cause the TIA to power up too slowly, but that's a stretch.

 

But, jitter on the 2600 is widely known to be caused by dirty or otherwise malfunctioning pots. I haven't seen anybody claim that addressing the pots didn't fix the jitter problem.

[SoundGammon]

I center the pot and put in some 99% rubbing alcohol and then I use my air tank hose and blast it out drying it! Works great!