Neumann KML lavalier mic - schematic needed

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Vac11

Well-known member
Joined
May 2, 2014
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383
Location
Czech Republic
Hello,

Im repairing Neumann KML lavalier mic from 70s. This mic has km85 capsule. Output transformer bv 151 looks to me like 2:1. There was 22.5V baterry in small "psu".

Need to bring it back to life and rebuild it to P48 standard if needed.

Unfortunatelly it looks like theres no schematic online. Any help is much apreciated.

Thanks

M.
 

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Any chance it might have a similar schematic to the KM84 or U87? Doesn't look particularly complicated, so reverse-engineering should be quite feasible.
 
Ok, here is first bird to disscusion. (one resistor, output cap and transformer is in PSU chassis though).
Dont know what is the part with three legs on the bottom side of pcb. Looks like transistor to me, but im not sure...


KML.jpg
 
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As drawn, there is no polarisation voltage for the capsule.
This seems unlikely to me, since the capsule is not an electret type.
The 27K//100nF looks 'strange' to me at the drain of the FET.
 
Thanks Ruud, I think polarisation voltage was somehow taken from second 22.5V baterry.
I found some good documents with technical info about this lavalier mic (see attached files). Have to try second look on circuit and 27K/100nF parts.

PV.jpg
 

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  • docu0062_historical_collection_KML.pdf
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  • opin0084_KML_03-1967_E.pdf
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