Faulty M149
Author: Hynek Kocourek
Date: 12/03/2005
Hello Martin & others,

I just bought a new M149 (the 75 ann. edition) and I'm getting no sound. A few indications lead me to believe it's the power supply that causes the problem (as you know this version comes standard with the N149V vintage PS). Unfortunately I have no other N149 around for a swap test.

- The manual talks about the PS "ON" light staying dim and then turning bright when the mic is connected. This is not happening. The light is fairly bright after turn-on and stays so.

- The voltages on individual pins on the PS do not correspond with the manual (70V,-70V,30V,5V...). The manual also says the voltages are not introduced until the PS electronics detects the microphone properly connected, so I plugged the mic in, waited for a minute and measured the voltages on the connector from inside the box - no difference. Most pins show no voltage, then there's approx. -30V on one pin and 5V on another. Certainly no sign of 70volts anywhere.

- I measured the cable and it is in perfect condition.

- The internal switching PS outputs stable 12V which at least does not seem necessarily suspicious so I guess the culprit might lie somewhere down the road from there.

Why I'm asking you: I'm just trying to avoid sending the case 700km back. Maybe I could send just the PS? Should I send it back to the vendor or directly to Berlin? Is there something further I can do to get closer to identifying the problem? There is an unattended pin array on the PS's PCB on the side under the switching PS which I assume is for quality inspection purposes (?) Should I perhaps measure the voltages left to right and get back to you?

Thank you very much,

Hynek, Czech R (mic purchased in Germany)  
Hynek Kocourek
Martin Schneider/Neumann
Hynek Kocourek