Telefunken 251F Power Supply

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deveng

Well-known member
Joined
Jan 11, 2005
Messages
371
Location
California
Anyone have a schematic for this Telefunken ELA M251 F power supply?  This is the "imported" low cost supply that came with the ELAM 251F version microphone.  I want to drop the B+ voltage from 120V to 105v.  I can figure it out if I take it apart but it would be much quicker to deal with if I have a schematic!

telePS001.jpg

telePS002.jpg
 
Ok I opened it up and found the B+ adjust trimmer.  I expected it would only move the supply by about +/-5%.....but it goes all the way down to about 75V and well above 120V.  I can indeed adjust the B+ to 105v!  No mod needed there.  But while poking around I found the filament supply is not working.  It looks like a typical LM317 circuit (it does have the LM317 in there).  So I'll need to fix that.

Would still be nice to have the schematic if anyone has one. 
 

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