Hello everyone, I am new here, but not new to recording / audio. I had the same problem with my HTC ATT Vivid, Plugging in the headphone does not silence the speaker, nor play through headphones. I have seen many posts about lint in the jack stopping the contact. This is probably not the case. Resist the temptation to shove a pointed object into the jack because it will damage the actual contacts that make the headphone work.
The headphone plug is a standard 3.5mm or I used to call them 1/8" TRS plugs (Tip, Ring, Sleeve). TRS is what allows stereo, one part of the plug is "common", one is left, one is right. The plugs with 4 sections, are "probably" for a type of headset with a microphone and a wire, as opposed to bluetooth that uses no wire. A standard 1/8" MONO plug does not have 3 sections (TRS), it only has two.
Here is what about 2 hours of measuring and observing fixed my headphone problem. Because I kept reading things like "I pushed the plug in hard, and it worked, I wiggled it from sided to side and it worked, or all of a sudden it quit working. Then I saw something like I got a warranty replacement, it worked for a while then quit.
Those 3.5mm plugs do have a surrounding plastic, or metal ring right above the actual plug. From my testing with 3 different TRS plugs, and a fourth was a set of high end pro audio headphones, what might be your problem is that the actual plug is not able to go all the way into the phone. It may look like it, but what I found was HTC's headphone jack may actually be made to tighter tolerances than some phones that have a more "sloppy" tolerance. These jacks do have standards of manufacturing. The TIP, RING, and SLEEVE have to fit almost perfectly. This may take some experimenting. In my situation, I took that case off of it, which is a snap on plastic case, and the couple of millimeters it kept the plug from going in made it so none of the TRS made proper contact.
I had to shave a bit of the case, which looked like it had plenty of room. That fixed it. If you are brave, cut gently, shave a little of the plastic that is right above the actual plug, maybe allowing it to go in the jack better. I do not believe you can push the jack in too far, I did see a bottom on it, and if that bottom isn't a built in stop, all that will happen is as you push the modified plug in, it would first work, then pushing again would shut off the headphones, turn the speakers back on. The jack in the HTC is tight, the contacts are close tolerance, which means, holds better, but it is less forgiving.
A good start, is be sure you take the HTC out of any sort of case, then plug your headphones in. If that fixes it, the plastic or metal above the plug is bumping on the case.
I can find nowhere there is a software setting, or control for the sound except the built in "MEDIA VOLUME" which controls both headphone level, and speaker level. It isn't like a pro audio amp where you can listen to both headphones, and speakers at the same time. Plugging in a plug shuts the speakers off.
This being a software issue is slim, it is mechanical. If your player plays through speakers on the phone, it should play headphones too. (shutting off the speakers when the plug is in right.)
Watch out for right angle plugs. That rippled looking boot (strain relief) right above the plug is notorious for the plug not going in right.
Hope this helps.
Maybe someone can help me in return. The VIVID does not play FLV files, requiring an app. Unbelievable, Real Player App doesn't do it. Which player / organizer do you like, maybe something that will play a lot of formats beside FLV. The built in music app plays mp3 just fine.
Art C
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