318 Transmitter Fault Finding (50W/40W) TB7100 Service Manual
© Tait Electronics Limited October 2005
Task 24 —
Power Control
In this task any faults in the power-control circuitry will be located:
1. Measure the voltage at pin 8 of IC303 (see Figure 14.11 and
Figure 14.12) in the power-control circuit. The voltage should be:
2. If the voltage is correct, go to Step 3. If it is not, enter the CCTM
command 32 and return to Task 23
.
3. Measure the voltage at pin 10 of IC303 in the power-control circuit.
The voltage should be:
4. If the voltage is correct, go to Step 5. If it is not, go to Task 25
.
5. Enter the CCTM command 32 to place the radio in receive mode.
6. Check C322, C324, R342, R347 (see Figure 14.11 and
Figure 14.12) and R396 (see Figure 14.18 and Figure 14.19) in
the power-control circuit. Repair any fault. Replace IC303 if none
of the other components is faulty.
7. Confirm the removal of the fault and go to “Final Tasks” on
page 123. If the repair failed, replace the main-board assembly and go
to “Final Tasks” on page 123.
pin 8 of IC303: 7.4 ± 0.5V
pin 10 of IC303: 4.8 ± 0.5V
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