Sennheiser MKH 40-P48 User Manual download pdf (Page 5)

MKH 20...70

04/2005 5/53

Description

Contents of these Service Instructions

These Service Instructions summarize the technical documentation on the

microphones MKH 20 to MKH 70. Information concerning all models is given first,

followed by detailed data on individual microphones.

Service concept

Tests and checks for faults are divided into 3 parts:

1. Acoustic test

2. Capsule check

3. Test instructions

General service information

In the event of a service incident, perform a general functional check, first. For this

purpose, connect the microphone to an amplifier under field conditions and

monitor the microphone using headphones. Speak into the microphone, shake the

microphone, and move the connection cable.

In most cases, this acoustic test will give you a first impression of the kind of fault

that occurred. Perform all subsequent testing and measuring measures according

to the following test instructions.

Checking the microphone capsule

To check the microphone capsule, disassemble the microphone, first.

For the MKH 60 and the MKH 70, unscrew the sound inlet, first.

Loosen the two countersunk head screws on the housing and then use the XLR con-

nector pins to carefully press out the frame together with the capsule. To further

disassemble the microphone, loosen the three screws on the capsule and then pull

off the capsule.

Attention!Before you touch the connections 1 and 3, touch the capsule housing to avoid

damage due to electrostatic discharge. When connecting measuring equipment,

always establish the connection to the capsule housing (pin 2) first.

Checking the capacitance

Capsule connections (bottom view):

Use a capacitance meter to measure the capsule capacitance.

Type 1; KS 20, 30, 40, 50 Capacitance: 40 to 45pF

Type 2; KS 60, 70 Capacitance: 30 to 35pF

Checking the insulation

Capsule connections (bottom view):

Use a multimeter (20MΩ range) to measure the capsule resistance.

R>20MΩ (out of range)

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Sennheiser MKH 40-P48 User Manual Page 5