Modifications for the Kenwood MC-55
MC-55 Change in mic element (T91-0328-08)
Trio-Kenwood Communication, inc.
Service Bulletin no. 953 (4-5-1989)
The new Mic element for an MC-55 comes in two pieces. One piece is a two pin ECM and the other piece is a spacer. The spacer is required as the new ECM is half the side of the old one. The wiring configuration is somewhat changed for the installation of the new Mic element. The figures below show the original configuration, the new configuration, and the assembly. The black wire is not used with the new ECM and a 330 ohm resistor is installed on the foil side of the microphone amplifier board. The leads of the resistor should be insulated with electricians tape or shrink tubing.