MXL V63M how to open the case

[Rick H]

My V63M after 22 years has become noisy. I suspect bad caps. I live in Honduras and ordering a kit of parts is very expensive to ship here but I can buy parts locally. My first question is: How do I open the mic case to expose the circuit board?

 

[Khron]

My V63M after 22 years has become noisy. I suspect bad caps.

What sort of noise? And why caps?

And as in 99% of cases, you unscrew the bottom bell.

 

[rock soderstrom]

Welcome Rick,

My V63M after 22 years has become noisy. I suspect bad caps. I live in Honduras and ordering a kit of parts is very expensive to ship here but I can buy parts locally. My first question is: How do I open the mic case to expose the circuit board?

Yes, describe the noises (or record them) so that we can help you better. I suspect that your microphone has problems in the high impedance area or in the microphone capsule itself due to moisture (and dust?).

 

[Rick H]

First I must learn how to open the mic. I have instructions for that now. I suspect capacitors only by hunch. With 20 years old electronics caps are the first thing to look at. While I have the mic apart I will look for dust, clean up the circuit board, look at solder joints. I am well experienced with electronics repairs but this is the first microphone I have serviced.
The noise is a low level continuous noise, but random pops which make the microphone unusable. When I leave the mic powered for several hours the pops decrease in rate and volume (as if electrolytics are re-forming). The pops are the bigger issue.
I now have the mic disassembled.

 

[Rick H]

At first visual inspection, the insides are very clean, like brand new. No visible dust.

 

[rock soderstrom]

The noise is a low level continuous noise, but random pops which make the microphone unusable. When I leave the mic powered for several hours the pops decrease in rate and volume (as if electrolytics are re-forming). The pops are the bigger issue.

the symptoms you describe match my diagnosis very well, this is not an unknown problem that you describe. I suggest you replace the capsule with another (working capsule) or install a ca. 60pF capacitor as a “dummy capsule”. If the problem is then gone, you know what is going on. An intensive cleaning of the high impedance area with 99% alcohol would also not be wrong, the impurities / moisture are usually not visible to the eye.

Sometimes it also helps to place the microphone in a dry, warm place for a some days...

 

[rock soderstrom]

I am well experienced with electronics repairs but this is the first microphone I have serviced.

The situation in condenser mics is indeed somewhat special due to the extremely high impedances (1G!). Even the slightest contamination lead to the problems you mentioned.