Troubleshooting Flow Chart For 25W Transmitter (Sheet 2 Of 3) - Motorola Commercial CM Series Service Information

Troubleshooting Flow Chart for 25W Transmitter (Sheet 1 of 3)

Troubleshooting Flow Chart for 25W Transmitter (Sheet 2 of 3)

2.1
Check Q101, Q102,
R153, R136, R165,
R122, R168 & R137
Check U103 before re-
Check Q102, R139,
R155, R166, R126-
R128, R169, R138,
R175, R147
U102 Pin 3 =
Check U102 before re-
placing Q105
No or too low power when keyed
No
DC
Voltage at
<3.5V
U103 Pin
10=8.9V
Yes
placing U101
<2V
No
DC
Voltage
8.7V
Yes
Check PA
Stages
DC
Voltage
at Q101 & Q102
base=0?
Yes
DC
>4.5V
Voltage
at U103
Pin 8
3.5 to 4.5V
Measure DC Voltage at U102 Pin 1
>3V
Pin 1
Voltage
2-3V
Check Final PA Stages
No
Check U403
Check resistive network at
Pin 9 and 10 of U103
before replacing U101
Check resistive network at
Pin 2 & 3 of U102 before
replacing Q105
3-5