Neumann KML lavalier mic - schematic needed

Help Support GroupDIY:

Vac11

Well-known member
Joined
May 2, 2014
Messages
337
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.
 

Attachments

  • IMG_20211207_202726.jpg
    IMG_20211207_202726.jpg
    68 KB · Views: 44
  • IMG_20211207_202742.jpg
    IMG_20211207_202742.jpg
    71.7 KB · Views: 42
Last edited:

Khron

Well-known member
Joined
Apr 8, 2010
Messages
2,099
Location
Finland
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.
 

Vac11

Well-known member
Joined
May 2, 2014
Messages
337
Location
Czech Republic
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
 
Last edited:

RuudNL

Well-known member
Joined
Apr 26, 2009
Messages
2,519
Location
Haule / The Netherlands
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.
 

Vac11

Well-known member
Joined
May 2, 2014
Messages
337
Location
Czech Republic
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
 

Attachments

  • docu0062_historical_collection_KML.pdf
    109.7 KB · Views: 6
  • opin0084_KML_03-1967_E.pdf
    149.1 KB · Views: 9

Latest posts

Top