Tait TM8100 mobiles Service Manual page 376

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