I am wiring an electric guitar.
Part of the wiring process is a tone capacitor (0.022 µF) which is attached to a linear taper potentiometer, when the potentiometer is turned, the capacitor is brought into the circuit and takes away the high end treble of the signal, essentially a low pass filter.
I have wired a few guitars and am comfortable with the basic circuitry, I have never had this problem.
I have the guitar wiring hooked up to an amp and I am listening to it, when I heat the solder, the capacitor to one of the arms of the potentiometer I have about 5 seconds of it working as it should, rolling off the treble, being active in the circuit, until it cools down and blam it stops working.
Mind you the cap has two arms, one grounded to the outside of the pot and the other going into one of the arms of the pot, it’s only the one attached to the arm that needs to be warmed.
Other things I have troubleshooted:
- I have tried four different capacitors, all behave the same way, two of the four are 0.047 µF and the other two are 0.022 µF. One is rated for 400 V the other for 100 V although this doesn’t mean anything in guitar as there is no voltage running through the circuitry.
- The 400 V one seems to last the longest but my guess is because it can retain the most heat as it is physically the largest and allows the solder to stay warmer longer.
- I have tried the capacitors in each orientation (if there is an orientation to the capacitor)
- I have replicated this behaviour of only working when warm dozens of times.
I guess it has to be a cold solder joint problem. Is that suspicion right?
The solder I am using is lead free.
Is it possible the solder is creating an oxidation later as it cools? All other connection in the wiring are working as normal. None of the parts are damaged.
I can provide sound and video and pictures as needed.