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R/E/P => Klaus Heyne's Mic Lab => Topic started by: Bo HansÚn on May 07, 2021, 04:47:26 am

Title: Nevaton MC/MK-51 tech info
Post by: Bo HansÚn on May 07, 2021, 04:47:26 am
Maybe a long shot but I'm giving it a try.

Is there possibly someone who has a schematic on the Nevaton MC/MK-51 microphone?
It is unusual, but I have now received two of these microphones for repair from two different customers.

I have been in contact with Nevaton in Russia but they do not respond, and Nevaton Europe does not want to help with schematic or technical advice, they want the mics to be sent to Russia for repair, but none of the customers are eager to do this.

I normally do not have difficulty for drawing/tracing the electronics in a microphone even if it is complex, but these are full of Russian components with tricky marking/text.
Of course, it is possible to sneak out component type and values, but it saves a lot of time and there is less risk of misunderstanding with a schematic.

Title: Re: Nevaton MC/MK-51 tech info
Post by: klaus on May 07, 2021, 03:15:16 pm
I cannot contribute a schematic for your FET Nevaton, but all FET condenser mics with discrete components follow a basic circuit architecture which is fairly easy to troubleshoot:

1. Check supply voltages into the mic
2. Check that the FET works, by checking the rough voltage at the drain, and drain-to-source differential prescribed for the specific type of FET used in the mic
3. Check proper polarization voltage, by measuring at the input of the last resistor connecting to the backplate wire (You cannot measure the output voltage of that resistor due to its high resistance value)
4. Lift one leg of all capacitors, one after another, and measure whether the stated capacitance is reached

That should be a good start to get somewhere.
Please report back.
Title: Re: Nevaton MC/MK-51 tech info
Post by: Bo HansÚn on May 07, 2021, 04:19:33 pm
Thank you Klaus,

Sure, if it was a similar simple setup and think of electronics as for example Neuman or AKG most common mics, it would not have been a problem to find the measuring points on the circuit board.
But this is a messy circuit board, and looks like a pretty odd circuit solution with many switching functions, so in this case I would appreciate having a schematic on the workbench.

Ok, I do not give up so easily, I will return and share with you the experiences of troubleshooting these mikes.
One is noisy and crackling and the other is weak and unclean.