Substantial improvement obtained!
I had a slowly growing sense of “D’OH” as I was writing up my second approach: I realised that the contacts I’d adjusted couldn’t possibly have included a tip connector, and my remaining problems seemed to be with the tip. Of course the phone needs four wires to cope with ground, microphone, left and right channels, and while I’d adjusted four contacts, two were for the same connection, effectively gripping the “neck” of the plug. My previous photos even show where the tip contact is, and like the first pair that I had to drill to get at, it’s inaccessible. Opened things up again, drilled into the back face of the socket to get at the final connector, tightened it up, and had my first dropout-free walk while listening to audio in over a month…
In the above image of the rear of the headphone socket, the large circular hole is part of the original structure of the socket, but the smaller circle connected to it is drilled out with a 1mm drill bit. You can see the tightened tip connector glinting through that smaller circle (actually that’s levered out a little far). The 1mm drill bit is definitely large enough, but the position that I’ve drilled in there is not ideal: if doing it again I’d go 0.5mm further left. As it was, I could see the connector through the hole, but it was a bit of work to get a needle behind it to lever it out/tighten it up.
This isn’t perfect: I still find that one channel or another will just drop if I rotate the plug to the right angle, but once both channels are playing, there are no drop-outs from pushing the plug left/right/forward/backward, and after dropping the phone in my pocket I can walk freely without interrupting the audio.
I’ll report back in a week to say whether the fix survives daily use.
Tips for anyone else trying this:
- Having a compressed air canister is handy, to make sure there’s no plastic dust left in the socket after you’ve finished working.
- Before you start to reassemble, take a careful look at what happens when you insert and remove your headphones a few times, just to see everything looks ok and the contacts appear to connect.
- I sprayed a bit of contact cleaner into the socket before closing things up.
- When reassembling the top section around the PCB before reinstalling it in the phone, I found that of all the metal clips that hold the two halves of its plastic wrapper together, the clips at each end got stuck bent a little outwards and so didn’t grip nicely during reassembly: bending them back in a little before clipping everything together helped.
- I’m now almost certain that you don’t need the 1.5mm drill bit: 1mm should be good for all three holes.