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[Dick Swaneveld]

One of my very dear TLM170's suddenly has a problem:
The attenuator switch stays (electrically) in the -10 position
no matter the position of the mechanical switch.
I have checked the switch and now I suspect the DC-converter board having a problem.

Is there a simple component known to cause this problem ?

Richard Leopold

[Dick Swaneveld]

I am sorry if I asked my question on the wrong forum.
Did I ??

Richard

[klaukholm]

I would post the question in the Neumann forum. you may want to include the manufacture date or SN in the post as there were some revisions of the electronics over time.

[Klaus Heyne]

Richard,
At one point all Neumann mic switches became magnetic reed switches: two thin metal reeds are encased in glassand one of them is moved in and out of a magnetic field (a simple magnet on the backside of the switch you move) which bends it slightly, closing contact with the other half.

These switches tend to fail quite a bit more often than the old-style mechanical contact switches Neumann used to use. The switch will move, as before, but the reed does not close the contact when the magnet moves towards it.

If you have a magnetic attenuator in your mic, this would be a likely target to examine, and is a  cheap fix.

[Dick Swaneveld]

Klaus, thank you for your reply.
I have looked at the switch and it is a real old-fashioned mechanical slide two position switch, not a reed version.
The switch is OK as I could figure out with an ohm meter.
Therefore I thought the DC-circuit would be giving the trouble.
I will post the Neumann forum: Odd that I did not think of that forum in the first place....

Thanks !
Richard

[Klaus Heyne]

Please let us know their response, for the benefit of all!

[Dick Swaneveld]

Will do !!!