Tait TM8100 mobiles, Service Manual

Page: 295 / 620

TM8100/TM8200 Service Manual Transmitter Fault Finding (>25W) 295
© Tait Electronics Limited November 2007
Task 14 —
Shaper and
Level Shifter
If the voltage measured in Task 13 is correct but not the current, either the
first PA or the shaper and level shifter for the PA is suspect.
Important
Ensure that the current limit on the DC supply is 3A.
And, when entering the CCTM command
331 x , do not
specify a value
x
higher than that recorded in Task 12 . Fail-
ure to do so may result in the destruction of the PAs.
1. If the
PAF TOP
can has already been removed, go to Step 5 If it has not,
go to Step 2 .
2. Enter the CCTM command 32 to place the radio in receive mode.
3. Remove the
PAF TOP
can.
4. Enter the CCTM command 33 to place the radio in transmit mode.
5. Enter the CCTM command
331 x
(where
x
was recorded in Task 12 ).
6. Check that the voltage at the gate of Q310 is (see Figure 11.11 ):
7. Enter the CCTM command 32 to place the radio in receive mode.
8. If the voltage measured above is correct, Q310 is faulty; replace the
board and go to “Final Tasks” on page 163 . If it is not correct, go to
Step 9 .
9. Check the circuitry between pin 14 of IC301 and the gate of Q310
(see Figure 11.11 ). If a fault is found, repair it, confirm the removal
of the fault, and go to “Final Tasks” on page 163 . If the repair failed
or Q310 itself is faulty, replace the board and go to “Final Tasks” on
page 163 .
gate of Q310: 2 to 5V