Pa Failure - Motorola APX 5000 Service Manual

5-56
PA Failure – Page 1 (7/800 PA)
1
Measure TX current
at 7/800 test
frequencies.
Is current less
than 350 mA?
No
Is current
approximately
500 mA?
No
Is current
greater than 2A?
Yes
Yes
Replace Q1001
Use a spectrum
analyzer and high-
Yes
impedance RF probe.
Measure RF_IN_2 at
C1001.
Is the frequency
correct?
Yes
Is the power
level about 3
dBm?
Yes
Measure power at
C1022.
Is the power
appoximately 36
dBm?
Yes
Measure power at
C1411, and calculte
harmonic filter loss.
Is the loss less
than 1 dB?
Yes
PA and harmonic
filter are functioning
properly.
If power issue is not
resolved.
4
See FGU
No
troubleshooting
charts.
Check U1110 and
No
see FGU
troubleshooting
charts.
No
Replace U1002.
No Repair any issues
with 1400 series parts
in the harmonic filter.
Troubleshooting Charts: PA Failure
Measure voltage at
pin 4 of U1001.
Is voltage
Yes
Replace U1002 and
approximately 6
V?
No
Measure voltage at
pin 5 of U1001.
Is voltage
Yes
Replace U1001.
approximately 7
V?
No
Measure voltage at
pin 3 of Q1102.
Is voltage
Yes
Replace Q1104.
approximately 0
V?
No
Measure voltage at
pin 1 of Q1102.
Is voltage
Yes
Replace Q1102.
greater than 1.5
V?
No
Measure voltage at
pin 6 and 7 of U1119.
Are Pins 6 and
Yes
Replace U1119.
7, 5V and
2.775V
No
6
Q1001.