Motorola XTL 1500, Detailed Service Manual, Page: 224 / 452

6815854H01-A June 15, 2005
Troubleshooting Charts: Flowcharts 5-63
5.6.52 RFPA Power Control—No or Low TX RFPA_CNTRL (700–800 MHz)—Part 2 of 2
Specific Notes:
1. Remove Q0954. If proper power is restored, repair/replace Q0954. If the problem still
persists, check for proper operation of U0958-1, and replace U0958 if not functioning
properly. If U0958-1 operation is correct, refer the controller section in the theory of operation
chapter.
2. Remove D0950. If proper power is restored, inspect R0942-5, R0991, and U0956-4. Replace
D0958.
3. Inspect R0974-5.
4. Remove R0974. Measure U0963, pin 5 voltage. Replace R0974.
5. Inspect the current limit and temperature cutback circuitry (refer to the power control section
in the theory of operation chapter).
6. Adjust the Power Detector Calibration via the Tuner software (see the tuner Help text) and
monitor the output power while the transmitter is keyed. If the circuit is functioning properly,
output power will decrease if the softpot is increased, and output power will increase if the
softpot is decreased. If the circuitry is not functioning properly, then inspect U0952, U0956-2,
R0971-3. If the problem persists, refer to the controller section in the theory of operation
chapter.
7. Retune the Power Detector Calibration if any circuitry is repaired/replaced.
8. Adjust the power via CPS (see the Help text) and monitor output power. If the softpot is
decreased, power will increase; if the softpot is increased, power will decrease. If the circuitry
is not functioning properly, replace U0959 and retune the power via CPS (see the Help text
for complete procedures). If the problem persists, refer to the controller section in the theory
of operation chapter.