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So a while ago I wrote about my headphone problems with the HTC HD2 mobile phone. The slim version is that when I tried to use any of my normal off the shelf headphones the phone would perform random actions seemingly on its own. These actions ranged from dialing the last dialed number, to launching Windows Media Player to actually shutting the phone off. As you can imagine that was quite annoying.

If you read through my last post you will see I edited it a few times to report on my so called progress in resolving this issue. The last update titled "The End" left me thinking I had found a solution by way of the very cheap and easy to purchase "iphone 3G headphone Handsfree Adapter Converter + Mic" from ebay. This is a little 3 pole to 4 pole adapter that works just fine except the cable that comes from it is extremely fragile. It constantly broke off at the bottom where it was attached to the 4 pole jack. This meant the inner wires would cross and it would end up doing the same random actions as if I wasn't using the adapter at all. Other side effects where that it would only play in mono and sometimes it would just deactivate all together and suddenly my music would start playing out of the loud speaker. Quite embarrasing.

Time to get all A-Team on its ass!

...

I ended up buying 3 of these adapters but when the last one broke I decided that I'd had enough. They all broke in the same way as described above. Really the adapter did more than I needed. I just wanted a simple 3 pole to 4 pole adapter with none of the push button microphone malarky. I didn't even want a long cable as it just means I end up having 1 and 1/2 meters of cable jammed in my pocket (combining the adapters cable length with my headphones cable).

To this end I decided to hack a couple of the adapters together to make my ultimate adapter. For the main body of the adapter I decided to use the 4 pole L adapter I mistakenly bought last time:

It was titled "Mini Jack 3.5mm Plug Right Angled AV 4-POLE adapter" and cost £1.99 + 99p for postage. As you can see in the third image where it is opened up, it's a simple thing. You can solder to the 4 poles, doing so in reverse order. So the top most one is actually the bottom most one on the jack, working your way down to the actual big silver bit of the inner casing which is the top most pole on the jack. That will all make more sense in a bit.

The next bit was to cut out the 3 pole socket from one of my broke adapters. I also made note of which cables were connected to which pole. That didn't really help me in the end since I had to refere to a couple of online documents for my final solution. Both documents are pinout diagrams for both 4 pole and 3 pole jacks. The first was the Apple iPhone headphone jack pinout which the phone expects and the second was for a standard 3.5mm audio jack which my headphones use.

Knowing all of that it was just a case of cross soldering the 3.5mm socket to the 4 pole L jack. I linked the left, right and ground poles and just left the 4th on the 4 pole adapter empty. I kinda fudged it up the first time but eventually got it. The problem I had was that my soldering iron has a rather large nib so it melted parts of the black plastic that seperates the poles on the 4 pole jack. That meant some of the plastic was underneath the solder point and the cable came off when I tugged a few times.

Once it was all soldered I plugged the adapter into my phone with no headphones connected. When it didn't explode in my face and instead displayed the headphone icon in the taskbar I decided it was time to actually hook up my headphones and give it a test. I loaded up Nitrogen (the audio player I use) and sure enough it worked a treat. I put the black casing back on and then bent the wires around to the side. As a final step I wrapped the whole lot together using rubber tape.

I've been using it for about a week now and have had no problems with it. If it does kack up in the future then I know it'll just be a simple job of soldering a dislodged cable back into place.

It does suck that I had to do all of this just to use my own headphones with my phone of choice. As mentioned in my other post, HTC are well aware of the problem and their solution is for us all to buy their £20 adapter cable. This was the only real problem I had with the phone so now I'm a happy chappy again.