Motorola 6864115B62-C - Page 183

Troubleshooting Flow Chart for 45W Transmitter (Sheet 1 of 2) 3-7
3.1 Troubleshooting Flow Chart for Transmitter (Sheet 2 of 2)
Pin 2
Voltage 0.62
* Voltage at
Pin 1?
NO
YES
Check PA Stages
No or too low Power when keyed
NO
YES
Replace U3401
Pin 3
Voltage 0.51
* Voltage at
Pin 1?
2-4V
Supply
0V
Bias 1 DC
Voltage at
TP3406?
NO
YES
PCIC U3501
Pin 24 2-4V
DC?
Check Bias Tuning
before replacing
PCIC U3501
Check Voltage at Pin 2 & 3 of U3401
Replace U3401
Replace Q3421
NO
0V
1-4V
Bias 2 DC
Voltage at
TP3407?
YES
RF Voltage
at TP3401
>100mV?
YES
RF Voltage
U3401 Pin 6
>3V?
Replace
Q3421
Supply
Replace Q3431
Check FGU (U3301)
NO
Check Components
between TP3401 &
C3417
NO
YES
ASFIC
U0221 Pin 6
1-4V DC?
Check Bias Tuning
before replacing
ASFIC U0221
Check Components
between ASFIC and
Q3431 before
replacing Q3431
YES
RF Voltage
Q3421 Gate
>1V?
NO
Check Components
between C3417 &
Q3421
YES
RF Voltage
Q3431 Gate
>4V?
NO
Check Components
between Q3421 &
Q3431
YES
RF Voltage
Q3441 Base
>5V?
Check Components
between Q3431 &
Q3441
NO
Check Components
between Q3441 &
Antenna Connector
Voltage
Voltage