Get yer panels off, I'll give yer a good servicin'
It was simple wiring inside so I traced it all out and got the following circuit. Lots of bits of mini coax connected to the shells of the potentiometers as a ground reference. This guitar has a double humbucker pickup so has a selection switch to choose which set of pickups is used.
No output from the jack socket when the strings were plucked so it was quickly narrowed down to a faulty volume pot wiper.
The offending article
- B500k COR-TEK pot
- Notionally 500k ohms logarithmic response
- Solder terminals
- 23.5mm diameter body, 11mm deep
- 8.7mm diameter mounting shaft, 10mm long to bottom of collar
- 6mm diameter splined spindle
During a bit of research I discovered that there are different log potentiometer response curves. Every day is a school day. There was no indication of the response curve type for the replacements but since they aren't matched to each other and adjusted by ear then I decided not to worry about it. The volume pot was a B curve and the tone pot had a D curve.
Anyway, parts arrived, were duly fitted and now there is something on the jack socket output other than 50Hz hum.