Telex Airman 850, Руководство по обслуживанию клиента

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Airman 850 Maintenance | en 21
Bosch Security Systems LLC
Customer maintenance manual
09-2021 | V07 | F.01U.264.819
The output measured should be -18 ± 3dBV (or 89 - 178 mVRMS).
Measure current of 12V Power Supply
The current should be 4mA ±1mA with sound pressure supplied to the mic and ANR turned on.
The current should be less than 1mA without sound pressure supplied to the mic and ANR
turned off.
6.1.2 Microphone sensitivity adjustment
If the sensitivity of the microphone does not meet the requirements from Microphone /
amplifier sensitivity check, page 20, readjust the sensitivity.
To adjust microphone sensitivity, do the following:
1.
Turn the gain adjustment control in the microphone housing, using a small screwdriver.
For more information, see the illustration below.
Clockwise adjustment increases output level.
Gain Adjustment
Figure 6.2: Airman 850 headset, boom microphone gain adjustment location
6.1.3 Troubleshooting mic failure
The microphone circuitry is in two (2) parts; the boom microphone preamp and main amp
located on the main circuit board.
Testing the Boom microphone assembly
To test the boom mic assembly, do the following:
1.
Prepare the boom mic assembly (shown in the illustration below) by disconnecting the
three small boom mic wires from the main PC board.
2. Connect a 3.3 VDC power supply between the boom microphone RED (VCC) and the
COPPER wire (GROUND), and connect a voltmeter between the boom microphone
GREEN wire (OUTPUT) and the COPPER wire (GROUND).