Hello, all. I recently received a pair of Apple //e Handcontrollers ( as shown) but it appears there is something wrong with the analog locations. While running Breakout, the paddle twitches and jumps all around. I wrote a small program that outputs the value of pdl(0), and saw that the value will sometimes spike while turning the knob, seemingly at random, but will never be above 244. Additionally, there is a large "dead zone" when the knob is turned all the way to the left... the value stays at 0 while turning the knob to the right a little. What could be causing the issue? Is it possible to recalibrate and / or clean anything inside the controller itself?
Atari paddles develope similar issues due to oxidation inside the potentiometer. You need to disassemble each paddle and the potentiometer inside. To fix the jitter, clean the contacts with rubbing alcohol and a q-tip. The only downside is that the screw that holds the paddle together is under the label, and I don't know how to remove it safely so that it can be reapplied.
Guides for the Atari paddles can be found on YouTube, but I doubt the process will that different for Apple paddles. Google "Atari Jittery Paddles" and you should get a ton of results. Sadly "Apple Jittery Paddles" didn't yield any useful results. But maybe you can fill that void.
Within each of the paddles (what you refer to as a handcontroller) will be a potentiometer (a round can with a protruding stem that rotates). Over time these potentiometers can get dirt/dust in them and end up in the state that you describe. A similar problem occurs in old audio equipment with volume controls - ever noticed scratching/static when adjusting the volume knob on older speakers? Its the same problem.
The good news is that you should be able to clean the potentiometers with a little contact cleaner (available from your local electronics store). Spray a little contact cleaner into each potentiometer and work through the full motion - say 20+ times and retry your testing. You should find that the values will be more what you are expecting. Just a warning, make sure you don't use anything like WD-40 or any other oil based product to clean the potentiometers - chances are you will make them worse and maybe non-repairable.
Good luck and let us know how you get on.
Alright! So, I followed the advice of the fine folks here, and have documented what to do. Hopefully, this will help someone in the future.
I started by slowly peeling back the sticker on the bottom, and found a small square hole with a clip inside. Using a very small screwdriver, I pulled the clip forward and was able to release the bottom of the controller.
Being able to see inside somewhat, I realized that there was a screw under the knob that I needed to unscrew. Fortunately, the knob pulls off with just a little force. No prying needed.
The bottom cover then came off quite easily. Because a cotton swab would not fit between the board and the potentiometer, I bent the straw of the electronic cleaner, placed it in the small gap, and gave a few quick bursts.
After spraying, I replaced the knob and turned it to the two extremes about twenty or thirty times, as was suggested. I could feel the knob becoming much easier to turn.
After allowing the cleaner to fully dry (I gave it five minutes), I replaced the bottom cover and screw. The controller came back together as if it hadn't been opened at all.
I then wrote a (very) short program to test the values of the controller.
The values came back greatly improved, only increasing or decreasing when I turned the knob. There were no spikes in the values as I tested it.
Finally, I tested it out by playing Breakout, and found that it now works perfectly.
Unfortunately, even a perfectly functioning paddle couldn't stop Woz from giving his opinion on my playing skill.
So, there it is. Thank you to the fine folks of this community for helping me out. I hope my experience can be used to help others
Like the terminator, one day you'll be back.
Thank you for the tutorial and sharing your results on the paddle cleaning. I had done that years ago for a set of Atari VCS paddles.