Tait TM8100 mobiles, Руководство по обслуживанию

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366 Transmitter Fault Finding (25W) TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
Task 15 —
Shaping Filter for
Power Control
If neither the voltage nor the current measured in Task 13 is correct, then
the shaping filter for the power-control circuitry or the CODEC and audio
circuitry is suspect.
Important
Ensure that the current limit on the DC supply is 2A.
And, when entering the CCTM command
331 x
, do not
specify a value
x
higher than that recorded in Task 12 .
Failure to do so might result in the destruction of the PAs.
1. Use the multimeter to measure the voltage at the
FIN
1
test point
(see Figure 12.8 ). The voltage should be:
2. Enter the CCTM command 331 x (where x was recorded in Task 12 ).
3. Check that the voltage changes to:
4. Enter the CCTM command
32
to place the radio in receive mode.
5. If the voltage measured above is correct, go to Step 6 . If it is not, go
to “CODEC and Audio Fault Finding” on page 399 .
6. Check IC301 and the surrounding shaping-filter circuitry
(see
Figure 12.8
). 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,
replace the board and go to “Final Tasks” on page 163 .
FIN1 test point: 18 ± 2mV (initially)
FIN1 test point: 1.1 to 2.7V (after entry of CCTM 331 x )