In the past I wrote an article about bad design and unreliability of Archos devices. I thought I should document one of my successful repairs for the benefit of others faced with the same problem. This problem exists on the Archos V2 Jukebox Recorder (with blue plastic bumpers in the corners and an internal lithium-ion battery) and almost certainly also on the Archos FM Recorder. It manifests itself as occasional disconnection (silence) of left and/or right headphone outputs. The problem is due to a small circuit board breaking off the pins of the headphone jack.
You first need to open up the device. The Multimedia Jukebox has the same case and there is a good guide on how to disassemble it. Basically, there are two screws on the top (small side above the screen), two on the bottom, and metal clips sticking out from the metal part of the case holding the plastic part. You can also slide out the hard drive and battery, but some bending of the top end of the metal part of the case is probably necessary for that. The result should be:
Now you can see the little circuit board that's soldered to the headphone jack pins. Breaks in the solder are probably not wide open; the sides of the crack are probably touching. I found I could easily move the small board away, leading to this picture:
Now, one could just solder the small board back and close up the device. I chose to go further, desoldering the metal part of the case from the circuit board so that I could access the other side of the main circuit board. Some of these solder connections were already broken, often ripping off some of the copper. I then removed he headphone jack, inspected it to make sure it was okay, and glued it back with epoxy so that it wouldn't move and stress the connections. I'm not sure if glue is the best idea in case the jack breaks. I put a short length of electronic component lead (thin solderable wire) in the holes alongside the headphone jack pins to reinforce the solder, and I soldered the small board to the headphone jack. Here is a photo of the underside of the board with the headphone jack removed:
While that side is exposed, it would probably be a good idea to inspect the charger jack and battery contacts, and clean the battery contacts. The charger jack is mounted on its side. If you look at the full version of the photo you can see how the side that's supposed to be touching the circuit board is actually to the right. This makes the jack far more vulnerable to stresses from plugging stuff in. I later had to repair the connection from the bottom/outer pin (which goes to the right) to the small jumper wire that connects it to the circuit board. The battery contacts can get dirty, making it seem as if the battery is worn out. I cleaned them using an abrasive pen eraser. Some people have reported bent contacts, so it is a good idea to make sure that they have not been bent. Later, you can clean the battery and the contacts at the other end. If the battery is old you could replace it, but if it seems to perform poorly it's quite possible that the contacts were dirty and it will perform acceptably after they are cleaned.
Finally, while reattaching the circuit board to the metal part of the case I fixed the solder connections. Where the copper on the circuit board was broken I had to clean off surrounding copper and solder to that. I found that desoldering braid was best for making a reinforced connection. The trickiest part of the reassembly was the top-back part of the case. One has to bend it to put in the hard drive and battery, and bending it back afterwards can be a problem. It might make most sense to put those in before soldering the circuit board to the case.