14: Maintenance
14-18
PRC1099A-MS
14.6.3
Detailed Board Fault Location
This section provides more specific information to measure the performance
of each board. You should have a understanding of the operation of the test
equipment (refer to “General Fault Location” on page 14-16 and “Basic
Board Fault Location” on page 14-17) to locate the fault area and then use the
information in this section to confirm the nature of the fault.
Supply Voltages
To check the radio supply voltages:
1. Connect an external 13.8V, 5A power supply to the PRC1099A. Use
either the PRC-PS power supply or the PRC-CA12V battery cable.
The PRC-CA12V cable includes a protective diode to prevent damage
if the polarity of the power supply is accidentally reversed. There is a
small voltage drop across this diode.
2. Turn the
Power
knob to
LO
.
Power
Amplifier
Board
No simple check without instruments.
Carefully check voltages and connections
before replacement.
Tuner Board
Tuner does not tune when
Whip Tune
button pressed.
Make sure antenna mount or long-wire
adapter is screwed into antenna post.
Synthesizer
Board
Transceiver operates in either transmit or
receive mode.
Board is operational.
Processor
Board
Multiple operating malfunctions.
Processor controls all of the tuning, mode
and switching functions.
Memory functions not retained.
Replace lithium battery. (Nominal life is 10
years).
Display
Board
Transceiver operating correctly but
display is not operating.
Check connections.
Junction
Board
+5, +8, +12V supplies missing.
Board defective.
Microphone
Transmitter does not operate.
Swap with known good handset.
Ground pin C of connector and touch
pin B with hand. If transmitter shows RF
output, microphone is faulty.
Table 14-3 Fault Location Table (continued)
Board
Symptom/Action
Possible Problem/Solution
