Tait TB7100, Service Manual

Page: 316 / 370

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