Reporting another satisfied customer with a sucessful repair thanks to this thread giving me confidence to try!
I've had my GP2X for about 18 months, with no problems, but was aware of the headphone socket problem from having read this board. This year, I set up my GP2X to take on holiday - new memory cards with videos, new batteries - and new headphones - D'OH!
The inevitable happened - the new headphones obviously strained the socket where the old ones hadn't, and a couple of days into the holiday hubby started complaining that he could hear my sound - pushed the jack in more firmly, and snap, the whole socket was rattling around inside the unit.
So spent the rest of the hol reading more and watching less than I'd intended.
When I got home, I looked up this thread.
My first problem came on opening up the unit - not having needed to open it up before, the screws were very tight, and the screwdriver was distorting the heads rather than unscrewing them. I finally managed to get it open by using WD40 in each hole.
When I finally got the back off, the loose socket was very obvious, as was the place it should fit. There is a round component just below that makes getting the socket back in place slightly difficult - it needs a sort of wiggle to get it back into the hole in the case.
The four little terminals that need soldering are obvious - one on the left, 3 in the right.
I had to buy a small soldering iron, as the one we had was much too large. The iron and solder cost me about £10.
Not having ever soldered before, I looked for links to help me. Most of those suggested upthread are now broken, but I found this a useful guide:-
http://www.epemag.wimborne.co.uk/solderfaq.htm
and this was less relevant, but has videos about how to hold the iron etc.:-
http://www.solder.net/technical/tips.asp
I followed all the instructions about 'tinning' my new solder head, and then practiced on the innards of a broken pair of headphones. I found that the thing that would be most difficult for the 'real' task on my GP2X would be getting a small enough blob of solder - holding the iron to the end of the solder rod melted too much off at a time.
I came up with the solution of snipping about 1mm from the end of the solder onto a piece of aluminium foil, melting this with the side of the soldering iron, then using the edge of the foil to nudge the blob to the tip of the iron. Then, I could apply it accurately to the right spot.
I had used Superglue to make sure my socket wouldn't go walkies again - a blob to stick it to the case around the hole, and another blob to stick it to the board underneath. It felt quite firm (but didn't work - the electrical connections still needed joining (I checked, just in case!))
So - I screwed up my courage and applied four little blobs. They are probably much too big for a neat job, but there's nothing else for them to contact - and it now WORKS!
I'm very pleased that this thread gave me the confidence to try for myself - I know that most people on this board are perfectly at home with soldering, electronics, pcb's etc - but I'm not!
I've no idea if the snipping solder technique is a usual one or not - the guides I read implied that the solder should be taken right from the end of the rod - but what I did worked well for this particular repair, which is why I've mentioned it here.