Neumann.Berlin Condenser Microohone Owner's manual

Neumann-Information 1
88 043 I April 1988
Re: Disassemblina and Cleanina of Neumann Condenser Microohones
The disassembli- of the microphones in amplifiers and capsule head is
described in the operating instructions which are delivered with each
microphone.
Attention:
-~-
It is by no means allowed to tauch with the finger the contact and isolat-
ing elements for the connection of the capsule head. Also the other high
impedance Parts of the circuit may not be touched. 4lready minimum grease
and dirt quantities tan diminish the isolation figures and Cause noise
voltages.
Cleaning the microphone amplifier:
- -
Existing dirt on components and contacts tan be removed by means of a
soft brush using a detergent on the basis of Freon, Kaltron or Frigen.
Microphone capsules:
-
The microphone capsules of U 89 i, TLM 170 i and the KM . . . miniature micro-
phones are constructed in a way that the total surface is connected to
0 Volt. For this reason these microphones are extremely insensitive against
dirt and atmospheric influences and should not be cleaned.
When microphone capsules had to be constructed in a way that the isolating
areas between the electrodes could be reached by dirt (the large double
membrane Systems of U 67, U 87 (A) i, SM 69, SM 69 fet, USM 69 i, IJ 47 fet)
after a long period of Operation noise voltages may occur. For cleaning the
membranes the capsule has to be removed from its protecting grille. At t-he
U 67, U 87 (A) i, U 47 fet microphones the 3 mounting screws at the lower
plate of the capsule head have to be removed and then the complete capsule
assembly tan be removed from the capsule head.
At the microphones SM 69, SM 69 fet, USM 69 i the disassembly of the protect-
ing grille is more difficult:
The black dot on the upper part of the grille (position O”) has to be
removed.
Behind the opening a spring is visible, this spring has to be
pressed back by approximately 1 mm, the
grille tan then slightly be lifted
at the front side. Now the
grille has to be turned by 180°, then another
spring becomes visible which has also to be pressed backward, now the
complete upper part of the grille tan carefully be removed. To prevent the
springs to be lost these should also be removed. The complete capsule
assembly tan now easily be removed from the lower part of the grillle.
pto.
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Cleaning the membrane:
Every membrane is carefully brushed with a very soft brush with distilled
water. The water with the dissolved dirt tan then be removed with very
soft blott ing-Paper. This procedure has to be repeated several times unt il
the capsule is really clean. Those capsules which cannot be cleaned by
this method have to be exchanged.
Cleaning the membrane by means of solvents is not allowed
These solvents are too thinly liquid and fugitive.
For careful cleaning then no time remains and inhomogenit
on the membrane;
ives may rema in
solvents could also transport dirt below the membrane fixing rinqs:
solvents tan also cool down the membrane strongly and then humidity tan
condense below the membrane which cannot be removed from there.
Besides that the use of solvents bears the risk that the mechanical tension
of the membrane is influenced.