Motorola APX 7000 Detailed Service Manual page 153

Troubleshooting Charts: PA Failure
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
Yes analyzer and high-
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.
Measure voltage at
pin 4 of U1001.
Is voltage
Yes
Replace U1002 and
approximately 6
Q1001.
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
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