Although I did pick up a NIB high impedance microphone on eBay for $3.00 (
), I really wanted to see if I could fix the OEM mic from Voice of Music. After a lot of effort and study, I discovered that the cap is just a pressure fit, although it appears that an adhesive may have been applied at the factory when new. The cap can be worked off with a small blade screw driver.
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When I got the mic disassembled, I found one of the wires loose, although I may have done that removing the cap. The shell is also filled with cotton wadding. I removed the retaining ring that holds the element in the cap, but the element appears to be glued into the cap, so I didn't try to remove it.
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I thought the crystal or ceramic element might be dead, but I connected the two terminals to my signal tracer and found it was working fine. But when I reassembled the mic, it didn't work. I found the positive terminal was shorting against the mic's shell, which killed it.
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I soldered new leads and reassembled the mic after bending the positive terminal away from the edge of the cap.
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I haven't finished restoration of the VOM tape recorder yet, but I tested the mic again with the signal tracer, then tried it in the microphone input of an amplifier and it seems to be working well.
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