Amplifier: Testing and Inspection

Inside Microphone, Function Test

With BOSE sound, and inside microphone (R74) is installed to determine interior noise (AudioPilot). This is switched directly with the amplifier (R12). If interior noise increases, the amplifer (AudioPilot) automatically increases volume according to a predetermined pattern.

After turning on the radio (R), the amplifier determines the gauge of the inside microphone voltage supply. If the result is OK, there is no reaction.

In contrast, if no inside microphone is installed, three short tones sound one after another.

In case of short circuit, three individual tones are heard.

Function Test

- Turn on the radio and tune in a station.

- Set the volume to approximately "20".

- Now lightly tap on the inside microphone (front interior light (W1)) several times.

The volume of the station selected on the radio must increase noticeably during the tapping. The procedure is done slowly.

- Stop tapping.

The volume of the station selected on the radio must decrease noticeably.