Troubleshooting Flow Chart For 25W Transmitter (Sheet 2 Of 3) - Motorola 6864115B62-C Detailed Service Manual

3-4

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

2.1
Check S3440,
R3442 and R3443
Check Components
between U3402-2 Pin7
and Q3421. Check
Resistive Network at Pins
5 & 6 before replacing
Q3421
DC
NO
Voltage at
U3402-1 Pin
3 = 8.8V?
YES
Measure DC Voltage at Pin 2 & 3 of U3401
Check Q3442 and
Resistive Network at
U3402-1 Pin 3
before replacing
U3401
DC Voltage
NO
at U3402-2
Pin 5 <8.8V?
YES
Check Q3422
Check PA Stages
No or too low Power when keyed
NO
DC Voltage
at U3501
Pin 23 =0?
YES
>6
<2V
DC Voltage
at U3402-1
Pin 1?
2-6
Pin 2 Volt-
NO
age 0.62 *
Voltage at
Pin 1?
YES
Pin 3 Volt-
NO
age 0.51 *
Voltage at
Pin 1?
YES
<2V
>6V
DC Voltage
at U3402-2
Pin 7?
2-6V
Check Final PA Stage
TROUBLESHOOTING CHARTS
If U3201 Pin 2 is high,
replace PCIC
Check Resistive Net-
work at Pins 2 & 3 of
U3402-1 before replac-
ing U3401
Replace U3401
Replace U3401
Check Components
between U3402-2 Pin7
and Q3421. Check
Resistive Network at
Pins 5 & 6 before
replacing Q3421