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R/E/P => Klaus Heyne's Mic Lab => Topic started by: jacobsworm on November 13, 2014, 06:50:42 PM

Title: PSU pin-out for Gefell UM92s
Post by: jacobsworm on November 13, 2014, 06:50:42 PM

Hello everyone.

This is my first post here ever. I am badly in need of a little expert knowledge. I have bought a pair of used UM92s mics from a japanese seller. It turns out the powersupplys are not original and one is malfunctioning (seems to be stuck in omni-mode and more noisy than the other). I have contacted Microtech Gefell, but they say that they cannot help me as the powersupplys are not original.
Their best suggestion is to have the mics converted to the current version (UM92.1S) and buy new PSU's - which would set me back 3000€. A bit of a bitter pill having already payed for the mics once.
My question is: Does anybody know the voltages and the pinout for the UM92S? Could it be run with a modified UM57-power supply? And does anybody know of someone who could manufacture a pair of PSU's?

I really hope that someone in here knows what power the mics need as Microtech Gefell wouldn't tell.

Jacob

FinlandStudio.dk

Title: Re: PSU pin-out for Gefell UM92s
Post by: klaus on November 13, 2014, 08:07:24 PM

Pin-out UM 92S:

#1: Audio (+)
#2: Audio (-)
#3: Electrical Ground, Chassis Ground and Shield
#4: Tube Heater
#5: B+
#6: Nothing
#7: Rear Polarization Voltage

While the voltages will be the same for the UM92S and the UM57, the pin- outs and connectors are different:

Pin-out UM57:

#1: Ground
#2: Audio (+)
#3: B+
#4: Heater
#5: Audio (-)
#6: Rear Pol. Voltage

While UM92S and UM92.1S share the same connector, the voltages (and pin-outs) in the latter are vastly different, due to a different tube being used (EF86). So a power supply suitable for a UM92.1S is not applicable for your mic.

If you cannot get ahold of an original supply for your UM92S or UM57 (its called the UN920 and UN61, respectively- try eBay.de),
you can hire Scott Hampton ("Hamptone") to make you one.

Best of luck!
KH

Title: Re: PSU pin-out for Gefell UM92s
Post by: panman on November 14, 2014, 09:00:19 AM

Yes, as Klaus says, try ebay.de! I don`t know the current situation of the availability of UN61/UN57, but my previous experience is that they are more rare, but pop up every now and then. However, N61 as well as N57 are found there pretty constant and can easily be modified into UN61/UN57 just adding some parts.
Esa

Title: Re: PSU pin-out for Gefell UM92s
Post by: jacobsworm on November 14, 2014, 02:43:59 PM

Thanks a lot for your answers! That really helps me. I am looking forward to getting the mics up and running.

All the best

Jacob