Neumann N149 Schematic

[Gus]

IIRC Oliver posted something about a sense circuit in the heater supply on a forum some years ago.
I would use a resistor to load the heater part when testing the supply to make sure it is in closed loop.
I would load all the supplies if I was testing/repairing one.

The build does not look that bad the PCB looks OK.
The use of a enclosed PS might be safer than an open frame switching supply.
A 12VDC 1.25 amp switcher should be easy to find if that part is bad.

You might be able to fix it there is an old thread at this forum that svart? started some that has good information about repairing switchers

You can't buy some devices a with leads anymore so you need to work with SMD.

 

[rogs]

.... The build does not look that bad the PCB looks OK...

The PCB itself maybe OK -- and the enclosed switcher is probably reasonably well constructed internally? ---
But the 'bent' metalwork brackets, and the wiring apparently randomly 'tacked' onto the PCB from all angles......

Not really quite what I would have expected to find in a $1000 Neumann product?....

I'm obviously a bit out of touch with what is acceptable manufacturing practice these days!

 

[Whoops]

Thanks Ruud

 

[Ritchie Paris]

A switching PSU in a Neumann microphone !!incredible NEUMANN ARE YOU SERIOUS ?

 

[abbey road d enfer]

A switching PSU in a Neumann microphone !!incredible NEUMANN ARE YOU SERIOUS ?

What's wrong with that?

 

[RuudNL]

What's wrong with that?

Not much, IMHO.
I use a tube microphone power supply with a switching PSU without any problems.
(Not a Neumann PSU BTW, but a DIY version.)

 

[ubxf]

What's wrong with that?

The credibility of the OP

 

[granger.frederic]

The credibility of the OP

In fact there are pros and cons with SMPS.
You can make ultra low noise PSUs more easily (with good output filters) , very good for small signals like preamps and tube mics (less for amps because it's regulated, not much headroom...), are smaller , lighter and cheaper ...
The cons are RFI/EMI, long term reliabilty, not easy to repair...

 

[abbey road d enfer]

The credibility of the OP

?
OP was just asking for a schemo...

Or did you mean "credulity"?

 

[ubxf]

Sorry i was joking and made a mistake OP was meant as the person you answered with What's wrong with that?

 

[LevinGuitar]

How much amperage goes on that 70v? Could it drive a tube in a standard way through 100k? Not asking for raising the voltage yet, but still as for mod ideas

 

[ZHOUJUN]

I feel that the design of the M149 microphone is an imperfect one, and the power supply is also a low-cost solution. Please note that when switching the direction of the M149, it is best to turn off the power first.

 

[jeremynothman]

You mean before switching the directional pattern? That, or moving the mic, both seem like crazy things one should need to switch off the PSU for.

The other day I used one of these (the mic sounded great on jazz kick), and the power supply weighed about 1/10th of the PSU for the Blue C12s that were also used on the session. That it is a switchmode powersupply is not a surprise given that. A bit sad to make a non-serviceable item, and attempt to charge $1K for a replacement.