Motorola HT Series Service Manual page 144

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