I have considered replacing the encoder but I can't help but think about how it worked (albeit in one direction) and then stopped all of a sudden, making me think it's something else. ![Undecided :-\](https://www.eevblog.com/forum/Smileys/default/undecided.gif)
Is there any way you would test this theory of the worn out knob before I shell out the money for a new one?
There are only 4 (or 5, if it has a push button) connections for an encoder.
There is, say, a ground connection and power connection and two outputs. There are electromechanical contacts in there that close and open and get sent through the output lines. The micro on the other end receives these two outputs A and B, and based on the order and timing of these pulses (which is called
grayscale gray code, I think), it determines if the knob has meaningfully moved in the up or down direction.
Both outputs are necessary to produce a step in either direction. All of the solder joints must be good. In both my faulty devices, up works fine, and down works 1/20 times. But 1/10 times, a down click gets recorded as multiple up ticks. So it takes about a thousand tries to get all the way down where you want without having to start over.
As the encoder ages, the signal noise and bounce changes. And the firmware guy who wrote and tested the code while using a brand new encoder will eventually learn what he overlooked. But that doesn't help you.
Theoretically, you might be able to get it working again with small LCR filter circuit on each output. Small decoupling cap and then a small value resistor between the encoder and the receiving micro. But you have no idea what the software filter and algorithm is on that receiving end. It could work, or it could be hopeless.
This why I want to replace the encoders in these two devices with two push buttons outputting gray code through a micro. Once the output is tuned to the right speed, it will never change based on how fast or slow you turn the knob, and it will have no mechanical bounce or wear. This takes the firmware guy on the receiving end out of the equation.