Avantone CK7 FET Microphone - Needed Repairs

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InTheBox

Member
Joined
Dec 9, 2021
Messages
17
Location
Spokane Valley, WA
Hello:

This is my first post on the forum. I am not an engineer, just an old guitar player with a microphone problem. I own an Avantone CK-7 microphone. Recently when I tried to use it for a recording session, there was a signal that came through the preamp into my DAW, but it was a very very weak signal. This microphone has always provided a robust signal. So, I know we have power because there is signal bleeding through, but very little amplitude. I have watched a number of You Tube videos now on repairing microphones, but none apply directly to my situation. I would appreciate some guidance from the experts on how to approach fixing this problem. I contacted Avantone, and the cost of the repair would equal the value of the microphone. I'm willing to attempt this myself. I tried to build my first guitar pedal last year. I made a mess of the soldering and never got it to work, but at least I gained some knowledge of the electronic components and what they are used for. My guess is that the problem lies with a transistor, or an electrolytic capacitor..... but I've never fixed a microphone before. Attached are some pictures I took of the Avantone. Your thoughts would be greatly appreciated.

Thanks,

Joe
 

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What voltages are you getting between ground (metal chassis / frame), and the positive terminals of each of those orange round tantalum capacitors?
 
Thanks for your response. I'll check on it this morning and report it back on the forum post. Need to have my coffee before I start playing with electricity. LoL
 
Can't really do that much damage with the heavily-current-limited phantom power supply, though...
 
Hope I did this correctly., Using my multi meter on Continuity, I got 159.6 ohms for C4. C3 ranged from 1 to 20 ohms, never a solid reading. C7 did nothing, No reaction whatever.
 
You are correct. Forgive my mistake. I just used the DC V setting on the multimeter. I set it at 200m and got the following readings.
C7 .3
C3 0
C4 0

I tried the other positions and they all gave a zero V reading.

Hope I did this correctly.
 
Oh, my apologies for not being even more clear - voltage readings are to be taken with the microphone plugged in, and phantom power on (y)
 
I also took the voltages using the AC V setting. I don't see a bridge rectifier on the circuit board so dont know if this is AC or DC voltage.

Using the AC V setting"
C7 2.0
C3 0
C4 0
 
As luck would have it, it would appear that even the component designators match.

What about the voltage between chassis and the banded end of D1, on the other circuit board?
 

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