Fixing Speaker Input

My speakers had an issue where the right speaker would sometimes cut out and wiggling the input jack would get it working again. Overtime the problem became worse until it was almost permanent. After testing the audio cable I ruled the cable out as a problem and focused on the input jack itself.

I pulled the board out of the sub-woofer where the power supply and amplifier boards are housed. The grey electrical tape in the previous photo is covering the soldered connections of a pair of wires I added to the amp -> sub-woofer connection to lengthen it enough that I could pull the board out of the box and work on it while still being able to test. The input jack and other input/output jacks were covered by a plastic enclosure to the left of the board in the photo. The plastic was both screwed and glued to the board for some reason.

I de-soldered the three points that connected the input jack onto the board. The top point was under glue that had to be scraped off before I could get to the solder. The gunk on the bottom solder point is excess flux from a previous failed repair attempt. That bottom solder point would end up being the probable issue.

I had to dremel through the plastic to get to the input jack. I somehow managed to not cut through anything else and was able to remove the jack.

I decided to solder wires to the board and solder the jack on the other end so I wouldn't have to keep re-soldering the jack onto the board each time I wanted to test or modify it.

With the input cable plugged in and testing the connection between the open end of the cable and the wiring connected to the jack, I found that my assumption of the configuration of the wiring to be incorrect. As seen in the previous photo, the order of the contacts on the input jack don't match the order of the contacts on the plug itself. Meaning that the bottom solder point in the third photo is the point for the right channel, the channel without audio. When I last tried to repair this the solder contact pad came off with the solder. I re-soldered the contact at a low temperature so I could manipulate it as a paste, and stretched the solder to reach the trace. This seems to have solved the problem.

My guess is that force on the input cable put enough force on the jack that the last solder point broke contact from the trace. With the speakers now working I just taped the jack onto the backside of the sub-woofer rather than re-soldering back onto the board.