Condenser microphone repair

Thread Starter

Yami

Joined Jan 18, 2016
352
Hi, I just got a SE2200a condenser mic to repair/have a look at - as it stopped working one fine day. Anything audio is something I'm very interested in and I like to sink my teeth into it. Surprisingly there is very little that I could find on the web about microphone design/repair/servicing etc. So firstly I'll be very grateful if you could direct me to any good sources.

Anyway back to the mic I have - the soldiering work looks very bad and there seems to be some white residue around the pcb.
1. How should I clean this off, I read that using IPA (99% alcohol) is also not good to use as it might leave some residue and cause noise issues.
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I checked the individual components (in circuit) and everything seems to be in order, obviously I didn't remove any components wanted to make sure how to clean it off after soldering job first.

2. I checked this capacitor and it didn't show any resistance it reads O.L.(normally with other caps it shows the caps charging up) It looks like there is some blackening on it as well. Could this be the culprit? The capacitor marking is 2A102J (whats the value?, 1nF?). The capacitor is placed between the drain and source of the FET. (photo 1).

3. There is a mysterious component - the marking on the PCB is G2 I don't think its a transistor. What could this be.
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4.I supplied phantom power from my sound card - I checked the voltage between pin2 and ground, pin 3 and ground - it show the correct 48V. But when I measured at these points from the mic it shows 38V.
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I tried speaking into and I was able to get an output, but the output clips the moment it gets even slightly loud. I could only describe it as when DC passes to an audio amplifier.

5. How could I check the capsule if it ok?

The person who asked me to have a look also did mention that when the mic died it gave off a burning smell
Thanks so much in advance for the help

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