Tait TM8100 mobiles, Service Manual

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376 Transmitter Fault Finding (25W) TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
9. Remove the
DIRC TOP
can.
10. Check the components of the directional coupler (see Figure 12.11 )
and go to Step 12 .
11. Check R340 between pins 6 and 7 of IC303 in the buffer amplifier
(see Figure 12.12 ), and then go to Step 12 .
12. Repair any fault revealed by the above checks. Replace IC303 if none
of the other components is faulty (see Figure 12.8 ).
13. Confirm the removal of the fault and go to “Final Tasks” on
page 163 . If the repair failed, replace the board and go to “Final
Tasks” on page 163 .
Task 23 —
Power Control
for PA Driver
In this task any faults in the path between the power-control circuit and the
PA driver will be located, as well as any fault with the PA driver.
1. Check for short circuits at the gate of the PA driver Q306 . Check
R333 , R336 (see Figure 12.8 ), C310 , R324 and R327
(see Figure 12.10 ) between the power-control circuit and Q306.
2. Repair any fault revealed by the checks in Step 1 . If none of the
above-mentioned components is faulty, replace Q306
(see Figure 12.10 ).
3. Confirm the removal of the fault and go to “Final Tasks” on
page 163 . If the repair failed, replace the board and go to “Final
Tasks” on page 163 .