Motorola HT Series Service Manual

8-54 Maintenance: 900 MHz Troubleshooting Charts
8.17.5 Troubleshooting Flow Chart for Transmitter
Check C163,
C127, and
C142 for open
circuit.
Is the fuse
F501 OK?
Is there a
short circuit
after C113?
Is overall
radio current
between 0.8 and
1.3 A when
transmitting?
Is the
voltage at pin 4 of
U102 between 2V
and 5.6V?
Is the voltage
at pin 32 of
U102 between
6V and 9V?
START
No Power out or Low
Power.
Ye s
Ye s
Check L104, L105, C120,
CR101 for open circuit.
Find and remove
short circuit from
antenna switch or
harmonic filter.
Low Power
Ye s
Replace
F501.
Ye s
Ye s
Ye s
Replace
U102.
No
No
No
Is the voltage
at R105 and
C116 between
1.8V and
2.2V?
Is the voltage at
pins 6, 5, 8, 9 of
U101 between
5.5V and 7.5V?
Ye s
Troubleshoot VCO
Replace
U101.
Replace
Q101
No
No
No Power
No
No
Ye s
No
Is the
voltage at pin 24
of U102 between
2V and 5V for High
Power, 0V for
Low Power?
Replace
parts.
No
Ye s

Motorola HT Series Specifications

General

Battery Type	Li-Ion
Waterproof	IP54
Operating Temperature	-30°C to +60°C
Frequency Range	VHF: 136-174 MHz
Number of Channels	16