Chosen Solution
Hello, for some reason my subwoofer(JBL 138) started producing static sound when it is not plugged in. I just brought it down, and it worked for the first day, then it started creating a fairly loud static. The subwoofer still works fine when plugged in(LFE) however at low volumes it is very discernible. I’ve tried different electrical sockets, all producing the same static. I’ve mostly run out of ideas to fix it, it does feel unlikely that it suddenly produced an error inside the actual subwoofer, however not impossible. What might be the cause of the issue?
Hi, Does the static sound mechanical (rattling vibration type sound) or electrical (crackly sound)? If mechanical it could be a loose fitting for the actual driver causing the vibrating rattle etc. If electrical you could have faulty capacitors on the power supply rails in the amp. Check for bulging or leaking capacitors and possibly for any obviously heat stressed components on the pcb. Here is a link to the service manual which provides a schematic diagram and a parts list which may be of some help.
