Motorola APX 7000 Detailed Service Manual page 155

Troubleshooting Charts: PA Failure
PA Failure – Page 3 (Aux Antenna Switch)
3
Lift shield SH11 and
check switch U1111
for functionality.
In RX mode, and main antenna
mode measure resistance from
pin 28 to pin 1 of U1111. Then in
RX mode and auxiliary antenna
mode measure resistance from
pin 24 to 28.
Is resistance
less than 10
Ohms?
No
Is supply to
U1111 pin 12
near 3.3 V?
Yes
Verify logic to pin 13 of U1111.
Pin 13 should be near 2.775 V
for the main antenna and near 0
V for the auxiliary antenna port.
Is logic correct?
Yes
Check for solder
shorts on the RF pins
1,2,23,24, and 28.
Were any pins
shorted?
Yes
Clear short, or
replace U1111.
Repeat resistance
measurement from center
Yes
pin of J101 and J102 to
pin 28 of U1111 for main
and auxiliary antenna
modes respectively.
No
Check pin 12 for
solder shorts.
No
Check pin 13 for
solder shorts.
If all else is OK, and
resistance is still high,
No
then replace U1111
and re-measure
power.
Is resistance
less than 10
Ohms?
Yes
4
Verify voltage divider
No
Is the pin
at R1183 and R1184
shorted?
under sheild SH13.
Yes
Clear short, or
replace U1111.
Verify voltage at pin
No
Is the pin
22 of U703 under
shorted?
sheild SH1. See
FGU trouble
shooting charts for
further information.
Yes
Clear short, or
replace U1111.
Replace defective
No
antenna connector
J101 or J102.
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