I found a Ibanez TS9 Tube screamer at a friends the other day, and it has some crackling issues. I thought I would try and fix it if possible.
Some serious constant crackling occurs when the "Level" knob is at 12 o'clock. But when you turn it down to 9, or up to 3, the crackling is almost non existent. I don't think the issue is the pot, but I could be wrong.
Has anyone ever encountered this particular problem before? Some guidance would be greatly appreciated.
#1, this subforum is for digital and DSP (digital signal processing) - there's probably a better place for this post. Unfortunately, only a moderator can move it.
#2 while I know nothing about the TS9 specifically, level knobs in general are usually arranged the same. One end of the pot is grounded. The other end goes to the signal source (like the output of an op amp, possibly through a DC blocking capacitor), and the "wiper" goes to the effect output or following stage. Based on your description, my first suspicion would in fact be the pot itself because it has a mechanical aspect (the wiper contact sliding along a strip of resistive material) which can bend, wear out, or get crud in it, interrupting the circuit either totally or in the way you described.
Next time I will post in a more appropriate area. But thanks for the tip.
Try spraying some electronics contact cleaner in the pot and working the knob back and forth.
Here's an example of someone cleaning the pots on an amp.
http://www.youtube.com/watch?v=0QvOepREO4k
This may be reaching a bit, but I had a similar issue on a TS9 and it ended up being the DC power jack solder joints. If you are using a 9v adapter to power the pedal, try freshening the solder joints on the 9v jack and see if that helps.