Condenser Mic Repair?

[dcrenshaw]

Hello everyone
This is my first post here. I got tired of a certain other unnamed forum, so I'm hoping to find more eh, fruitful grounds...

I'm at the end of my pitiful rope with a condenser mic, CAD M177. The problem is it cuts out randomly. First, I made sure it's the mic and not a bad connection. The CAD rep suggested I send the mic back to them. They'll fix the cartridge(capsule) for $115. Too bad I'm poor.

The sound is fine when the mic decides to work. All the elements should be alright I guess. Wouldn't a problem like this have to be a short in the wiring? If I replace the wires and resolder everything should that fix it? Or maybe that's wishful thinking... If anyone has any insight or idea about this, please please share it with me. I don't want to pay a hundred bucks to repair a hundred-fifty dollar mic!

[jaykeMURD]

First thing I'd do is open her up and look for obvious problems.

BTW, did the mic work fine originally, did this just suddenly happen?

[dcrenshaw]

The mic was fine before. The problem started a month ago and is occurring more frequently now. It's been kept in the same room for the past six month. It hasn't taken any abuse either.

I've opened the mic up as far as I can. The electronics on the circuit board appear to be in good shape. It looks like the capsule with the diaphram is well-encased, so I will need to cut the wire mesh to get inside. If there are any telltale signs to look for then I can check it. CAD isn't one to make this easy.

Thanks

[jaykeMURD]

Could easily be a bad capacitor or resistor- that's very hard to tell too!!

If the mic is handled fairly easily, it's probably not wiring. Unless you want to diagnose the problem, you're better off letting CAD handle it. You have to use specialized equipment (and know how to do it!) to diagnose a problem. Even then, it may be a difficult repair. Bad transformer or something! YUCK!

[PhilGood]

No No No!!! No mesh cutting! Have a set of jewelers screwdrivers handy. The body comes apart by taking the mount screw off, then the 4 screws around the sides. There should be a couple of screws that hold on the grill to a round metal plate. Just remove them an gently slide the grill off. Gingerly check the center screw of the diaphragm. I MEAN BE VERY CAREFUL!! If you slip, boom, capsule gone! Also, just tighten it, but do not let it spin then washer.

Now, check all the solder points, including the XLR connectors. That's where I am suspecting the problem is, since that receives the most push-pull activity.

For the most part, the mic is ALL PCB, lots of Op-Amps and mini components, so not too much in the way of wiring.

Good luck, and Via Con Dios!!!

[dcrenshaw]

thanks for the guidance there. hopefully i won't screw it up more than it is hehe...

[Jakedafake]

I seem to recall that the M177 needs about 8 ma of phantom power which is a lot more than most mics require.

Check that the phantom power specs on your mixer/preamp can supply enough power for your Cad mic which if not sufficient could well cause the erratic behaviour.

What preamp/mixer are you using?

[mbrebes]

I would check all solder connections and make sure there are no cracked solder joints. Also check wires to the capsule. If they are screwed down, are the screws tight?