Motorola GM640 Service Information - Page 25
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Troubleshooting Flow Chart for 25W Transmitter (Sheet 1 of 3)
2.0
Troubleshooting Flow Chart for 25W Transmitter (Sheet 1 of 3)
Check Components between
Q4441 and RF Output,
Antenna Switch
D4471,D4472,Q4472,
Check PA Stages
Check 9.3 V Regulator
U0641
Replace PCIC U4501
If U4201 Pin 2 is high,
replace PCIC
U4501,otherwise
check controller and
FGU
Check Power Setting,
Tuning & Components
between PCIC Pin 5
and ASFIC (U0221)
Pin 4 before replacing
ASFIC
Replace PCIC U4501
START
No or too low Power when keyed
Check if Pressure Pad closes S5440
Current
>500mA & <4A
>4A
increase
when keyed?
<500mA
Control Volt-
YES
age at
TP4402
>1V
NO
NO
PCIC U4501
Pin 14 9.3V
DC?
YES
NO
PCIC U4501
Pin 16 >4V
DC
YES
NO
TP4404
9.1V DC
YES
NO
PCIC U4501
Pin 5 > 1V
DC?
YES
YES
TP4403
>0.5V DC?
NO
Check Forward Power
Sense Circuit (D4451)
Short TP4403 to
NO
Check PA Stages
Check Forward Power
Sense Circuit (D4451)
3-3
Ground
Voltage at
TP4402
rises?
YES