On Wed, Oct 30, 2024 at 09:19 AM, Heinz wrote:
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Hi! I'm back in town and did the measurement.
Across the two capsule wires it's 10.2V when the microphone is working.?
To check the voltage when the mic is not working, I have to wait until tomorrow morning. Then it usually doesn't work and needs the warm-up time.?
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A DMM wil normally have an impedance of around 10MΩ. Can you check the make and model of your meter, to confirm that ?
If 10MΩ is true , then a reading of 10V is low. The mic will work, but sensitivity will be much reduced.?
If it measures even lower than that when first switched on,? then that would suggest a faulty component in the voltage multiplier output filter.?
It's more likely to be the the primary 0.1uF (100nF)? capcacitor, fitted between the 4M7 series resistor and ground, rather than the resistor itself.
Or - as I suggested earlier - possibly dirt underneath the capacitor itself???
Firstly though you need to confirm:
? the impedance of your DMM and?
? that the volts across the capsule are even lower at switch on
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