CCS800 | Service manual | Chapter 5 | Microphone stem adjustment en | 18
Bosch Security Systems | 2005-01| 3922 880 21112
AC input fuse F1
Replace power supply unit in case of fuse failure!
DC output pin assignment K2 1 2 3 4 5 6
+24V +24V +24V GND GND GND
5 Microphone stem adjustment
Microphone stem
When the microphone stem assembly has to be replaced, it is required that the input level of the microphone is adjusted
again by use of the preset potentiometer R72. This is due to the spread in sensitivity of the microphone capsule (approx.
±4dB).
Procedure
The adjustment is practical procedures to compare factory-adjusted units with units were the microphone stem is replaced
and to be tuned to the system level again.
Test set-up
• Audio sine wave generator
• Home made loudspeaker reference source or a professional sound level calibrator unit “A” (see figure below).
To make a home made reference source, mount inside an (empty) microphone head e.g. a paging bleeper as ref. Loudspeaker.
• CPSU.
• AC mV meter.
Measurements
Test procedure Comment
1 Connect the CCS800 unit with the CPSU. Select only one active microphone on the CPSU!
2 Connect to the ‘Line out’ of the CPSU the AC
mV meter
X12, see chapter 3.1.
3 Adjust the audio source to approx. 1kHz. The audio level of the loudspeaker should be distortion free and
at a level of speaking distance.
Take care that no acoustic nuisance from outside influences the
measurements.
4 Place the mic. of a factory adjusted CCS800
unit close to the loudspeaker on a fixed distance.
Make from an old DCN or CCS800 microphone head housing
an audio reference source (A)
Of importance is that for all measurements the distance
between loudspeaker and microphone is equal.
4a Measure the audio level on the AC meter. Take this level as ref. for the CCS800 units to be adjusted.
Repeat the ref. measurement for a check with other unit(s).
(The factory level adjustment is ± 1,5 dB)
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