Service manual

3-30 800 MHz Troubleshooting Charts
Is the fuse
F501 OK?
Is there a
short circuit
after C113?
Is overall radio
current between
0.8 and 1.3 A
when transmit-
ting?
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
Yes
Troubleshooting Flow Chart for Transmitter
Yes
Check L101, L102, C101,
CR101 for open circuit
Find and remove
short circuit from
antenna switch or
harmonic filter
Low Power
Yes
Replace F501
Yes
Yes
Yes
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?
Yes
Troubleshoot VCO
Replace
U101
Replace
Q101
No
No
No Power
No
No
Yes
No
Is the voltage
at pin 24 of
U102 between
2V and 5V for
High Power, 0V
for Low Power?