3M C960, Service Information

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18
Duplex Systems Only
The following procedure sets system audio levels for duplex systems so that headset/belt pack volume controls
have enough “range” to allow operators to adjust headset volume to their preference.
*Note
The microphone at the menu sign must be located within four feet of the vehicle for duplex
operation.
To set the audio levels:
1. Turn the base station MENU MIC SENS control to minimum (CCW).
2. Adjust the headset volume control to maximum.
3. Press the headset Talk switch, and set the base station outbound (DAY/NIGHT) audio levels to the desired
level at the post/sign.
4. Press and hold the headset/belt pack Talk switch, and turn the base station MENU MIC SENS control up
(CW) until feedback occurs. Then turn the MENU MIC SENS level control down (CCW) until the feedback
stops.
5. Check each additional headset/belt pack (to be used in the system) at maximum volume. Verify that feedback
does not occur. If feedback occurs, adjust the MENU MIC SENS level down until the feedback stops.
6. Lower the volume control on the headset/belt pack 2 levels from maximum, and check that the inbound
audio level from the menu mic is usable. If everything is all right, the audio will be too loud.
7. Compare this inbound listen level in the headset to the page audio level from another headset.
8. Adjust the MENU MIC SENS level down (never up) to match the page audio level as required.
9. If the inbound listen level cannot be made to match the page audio level, then more acoustic isolation is
needed for the menu mic and menu speaker.
This procedure ensures that feedback will not occur even if the headset/belt pack is run at its maximum setting. It
is also a measure of how the menu sign/post components are placed in relation to one another.
Duplex and Standard Systems
*Note
For Duplex systems, the microphone at the menu sign must be located within four feet of the
vehicle for duplex operation.
For Standard (half–duplex) systems, jumper J6 must be placed in the STD position.
The following procedures apply to both duplex and standard systems.
Alert Tone Level
The alert tone level is the volume of the alert tone heard in the headset.
To set the alert tone level:
1. Turn the headset off and then on. (This sets the volume control to midrange.)
2. Have someone drive a vehicle up to the menu sign. When the vehicle is detected, you will hear the vehicle
alert tone in the headset.