Installation
Adjusting Potentiometers
2-20 MC3000 Digital Deskset Operator and Installation Manual
(6880309L15-A)
To program parameter values:
1. After you enter the program, press the Mode Down button until you get to the param-
eter you wish to configure. Look at the LCD Display to find the parameter. The first line
states which of the parameters you are currently setting and the second line states the
parameter value.
2. Press the Menu/Home button to enter the sub-menu.
3. Press the Mode Up or Down button to navigate to the desired parameter value.
Press the Menu/Home button to save the new parameter value and exit the sub-menu.
Adjusting Potentiometers
The deskset must be opened for access to the potentiometers and trimmers on the main
circuit board. All microphones have separate potentiometers that are set to factory default
values and do not require adjustment. All outputs are put through a common potentiome-
ter (R75).
The default value for R75 is approximately 3.6 K ohms for 80 mV
RMS
. The
value for R75 is approximately 25 K ohms for 0.78 V
RMS
. Use a multi-meter to
measure the resistance between point A and B of R75:
Line (Receive Audio) Input to Handset Ear piece/Internal Speaker
The audio received from the radio can be adjusted using the Volume Control knob.
To adjust the line input from the radio receiver to the handset ear piece and speaker:
1. To increase the volume of both speakers at the same time, turn the Volume Control
knob clockwise.
2. To decrease the volume of both speakers at the same time, turn the Volume Control
knob counterclockwise.
Internal Condenser Microphone to the TX Line
The audio level is factory set, but if the sensitivity of the internal condenser microphone
requires adjustment, this can be done using potentiometer R113 on the main board.
To adjust the Internal Condenser Microphone:
1. Use a multi-meter to measure the resistance between point A and B of
R113:
2. Adjust R113 to increase or decrease the gain as measured by the multi-meter.
The lower the resistance value, the higher the gain. The default value for R113 is
approximately 22.7 K ohms.
A
B
A
B
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