Motorola CM160

Troubleshooting Flow Chart for 40W Transmitter (Sheet 1 of 3) 3-5
2.1 Troubleshooting Flow Chart for 40W Transmitter (Sheet 2 of 3)
No
Yes
Yes
No
Check bias tuning
before replacing
U504
Check PA
Stages
No or too low power when keyed
DC
Voltage
at Q101 & Q102
base=0?
DC
Voltage
at U103
Pin 8
Check U510
Check resistive network at
Pin 9 and 10 of U103
before replacing U101
Measure DC Voltage at Pin 2 & 3 of U101
Pin 2
Voltage
1.6V x Voltage
at Pin 1
3.5V
Replace U101
Pin 3
Voltage
1.66V x Voltage
at Pin 1
Replace U101
DC
Voltage at
PA_CURRENT
line?
Replace Q105
Check Final PA Stages
ASFIC
U504
Pin 5 1.64V
Check components be-
tween ASFIC and Q105
before replacing Q105
DC
Voltage at
U103 Pin
10=8.8V
Check Q102,
Q101, R122, R165
Check U103 and Resistive
Network at Pin 10 of U103
before replacing U101
No
No
Yes
>5V
2 to 5V
Yes
Supply Voltage
2-3V
Yes
No
0V
<2V