16
2.5
TROUBLESHOOTING CHART (COMM SECTION)
MESSAGE
RECOMMENDED REPAIR
Receiver has poor signal
reception (low
sensitivity)
Check comm antenna in installation for intermittent
connection and/or high VSWR.
Verify connection between power/volume control
knob and CPU Board.
Verify connection between CPU Board and Comm
Receiver Board.
Replace comm chassis sub-assembly (see Section 3.2.2,
steps 1-7)
Replace CPU Board (see Section 3.2.4)
Receiver audio is
distorted
Verify connection between CPU Board and Comm
Receiver Board
Replace comm chassis sub-assembly (see Section 3.2.2,
steps 1-7)
Replace CPU Board (see Section 3.2.4)
Receiver audio volume is
low or intermittent
Verify connection between power/volume control
know and CPU Board
Verify connection between CPU Board and Comm
receiver board
Replace comm chassis sub-assembly (see Section 3.2.2,
steps 1-7)
Replace CPU Board (see Section 3.2.4)
Receiver squelch is stuck
open (noise through audio
at all times)
Verify connection between Control/Display unit and
CPU Board.
Verify connection between CPU Board and Comm
Receiver Board
Replace Control Display unit.
Replace comm chassis sub-assembly (see Section 3.2.2,
steps 1-7)
Replace CPU Board. (see Section 3.2.4)
Transmitter sidetone
audio is noisy or
distorted
Check comm antenna in installation for intermittent
connection and/or high VSWR
Verify connections from CPU Board to modulator
transistor Q34 and from Q34 to transmitter.
Verify connection between CPU Board and Comm
Receiver Board
Replace comm chassis sub-assembly (see Section 3.2.2,
steps 1-7)
Replace modulator transistor Q34 (see Section 3.2.2,
steps 8-14)
Replace CPU Board (see Section 3.2.4)
Transmitter has low or no
power output
Check comm antenna in installation for intermittent
connection and/or high VSWR
Verify connection from CPU Board to modulator
transistor Q34 and from Q34 to transmitter.
Verify connection between CPU Board and Comm
Receiver Board.
Replace comm chassis sub-assembly (see Section 3.2.2,
steps 1-7)
Replace modulator transistor Q34 (see Section 3.2.2,
steps 8-14)
Replace CPU Board (see Section 3.2.4)
