Icom M120 Service manual

Technical
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IC M
Ml20
VHF MARINE TRANSCEIVER
MICMOD
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The original EM53 and EM56 microphones are no longer available.
The Ml20 can be modified to accept a replacement HM114 hand
microphone.
l- Remove the 6 screws on hack of the Ml20 holding the case in place and slide
the case off
2- Unplug the old mic from the MAIN board 5108 jack and remove
3- Unplug coax connectors from P501 and P502
4- Unplug interboard connectors P402, P503 and P504 , remove 8 screws holding
board down, then flip board over front panel to gain access to circuit side
5- Unsolder connector JlO8 (use extreme care to avoid board damage), then remove
6- Replace J108 with a (#936-05432) connector (make sure pins align I for 1 etc), solder
7- On bottom of MAIN board, jumper pin #l to pin #7 on 5108
8- Sleeve ends of a 4.7K resistor (#915-01171) and install between pin 5 of JlO8
and the T8 connector at point “M”
9- Reinstall MAIN board and all previously removed connectors and screws
lo-Thread new mic cord into radio, snug mic cord restraint into notch on side of
chassis and plug intoJto8The small 2 pin connector on the HM114 is not needed.
Note: Up/Down buttons will notfunction on the new mic.

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