53724 Microphone Broken

[rjk_165]

Hi,

I bought a Motorola 53724 Microphone a while ago for a Talkabout radio I have, and it worked fine for a while, but when when I used it this year, it seemed to be broken.

When you key up on the radio you see the red LED turn on meaning that you are transmitting... However, when you speak, you can't hear yourself over other radios. So I do know that it is transmitting, but the microphone seems to be shot, because the speaker function of it still works.

Anyone have any similar problems?

I'm posting to see what I can do about either getting it replaced via the retailer (Target online), or Motorola, or even cracking it open and fixing it myself.

[n2hbx]

Do you have another radio you can try it on? It might be a problem with the jack on the radio. The jacks can be problematic at times, even on the commercial models.

Larry

[cmdrwill]

The cords go bad on them too.

[rjk_165]

I do have another radio, and tested that... The problem is limited to the microphone.

[gewecke]

I agree, that it's likely the plug on the mic. (or the jack). I have the same mic and it's not a commercial mic. possibly the ptt switch but I doubt it.
Try tracing it out using a vom.

73,
n9zas

[cmdrwill]

Some of the speaker mics have a phantom PTT.. the PTT is sensed in the radio when the external mic is switched on drawing some current for the electret bias.

This is true on GP300/P110 radios.

[rjk_165]

Originally Posted by gewecke

I agree, that it's likely the plug on the mic. (or the jack). I have the same mic and it's not a commercial mic. possibly the ptt switch but I doubt it.
Try tracing it out using a vom.

73,
n9zas

I doubt it is the PTT switch as well. I have the radios and microphone right here with me, and I tested it on both radios. You do notice the transmit light turn on the radio, and you also notice that the other radio picks up the transmission... However, when you try to speak into it, it doesn't work. I have a feeling it has to do with the physical microphone...

Originally Posted by cmdrwill

Some of the speaker mics have a phantom PTT.. the PTT is sensed in the radio when the external mic is switched on drawing some current for the electret bias.

This is true on GP300/P110 radios.

My radio isn't as high-tech as those... I'm using the mic with a Talkabout T5420 and a Talkabout FV700.

I did notice that last year the mic did this, but over the summer it worked for like a week, then it quit again, and that leads up to now... I'm almost thinking of just hitting it against a few things to see if maybe something knocked out of place (what do I have to lose, it's already broken!) and if not, do you guys think there's anything I can solder or re-connect by cracking the housing open and looking inside? I want to see if I can get this going by Saturday, I was planning on using these for skiing. If there isn't a solution, then no problem, I'm not surprised lol.

[cabletech]

Open the case, use a ohm meter and check the mic element. If the mic is bad, then figure out where you maybe able to find a new element.

Simple troubleshooting.

[rjk_165]

I think I'll try that today. I'll let you know what happens. Thanks!

[rjk_165]

So I unscrewed the back off, and I took that green board out.

Here's what I got. The microphone seems to be connected to the first red wire coming out of the white box (the red wire being closest to the microphone itself)

I rubbed a screwdriver over the two little nibs of solder and you could hear it making that scratching/rubbing noise... But still no luck talking. Tips on where to go from here?

[rjk_165]

Another pic... Won't upload.


http://hostthenpost.org/uploads/773c...df4c633598.jpg

[cmdrwill]

Check with a voltmeter for the Mic bias.

[gewecke]

Tip; That's a electret mic element which usually requires 4-5vdc to pass audio, so it's possible that the source for it's power might not be present. I would trace the leads back from the element with a vom as stated before.

73,
n9zas

[rjk_165]

Of course the one day I need it, the meter is nowhere to be found!

I will try that... Where should I measure?

[cabletech]

check to see if you have any voltage between the red and the black. then plug and put your meter in ohms and again across the red and blck see if you measure any thing. if you have voltage all is good to that point.

Put your meter in about 2k ohms range. if you do not get a reading, then the element is dead.

[rjk_165]

Which red and black?

[cabletech]

This is trouble shooting 100 and he has failed the class.

[rjk_165]

Very funny :P

What I mean to say is did you want me to to measure the voltage by testing (what seems to be) the main supply lines, or the voltage that goes directly to the actual microphone?

[ecanderson]

I don't wish to hijack this thread, but have a question directly related to this subject, and it sounds like we have some folks here who understand these units.

Current Talkabout units use a single 3/32" 3 wire connection for audio out and mic. Plugging anything (even a bare 3/32" 3 conductor plug) into the jack fires up transmit. Can anyone elaborate on how these units are wired - (there's obviously some switching going on on the jack)? Need to get audio out only for some firing range headphones (no external mic) from the jack *without* disturbing the usual PTT action on the side of the unit.

[cmdrwill]

ecanderson,

Try a capacitor in series with the headphone hi side. Grounding the earphone hi side is what keys the tx.