Tait TM8100 mobiles Service Manual page 412

Task 9 —
Check LPF and
Buffer Amplifier
412 CODEC and Audio Fault Finding
If there is no test signal at the internal-options connector, then either
CODEC 1 is faulty or there is a fault in the LPF or buffer amplifier.
1. Remove the
CDC BOT
2. Check the signal at the junction between R224 and IC204
(see Figure 13.7). This should be:
junction of R224 and IC204: 0.7V
3. If the above signal is correct, go to
(IC204) is faulty; replace the board and go to
page 163.
4. Check the voltage at pin 1 of IC201 (see
pin 1 of IC201: 1.2V
5. If the voltage is correct, go to
based on IC201 (pins 1 to 3) (see
conclude with Step
6. Check the voltage at pin 7 of IC201 (see
pin 7 of IC201: 2.4V
7. If the voltage is correct, go to
amplifier based on IC201 (pins 5 to 7) (see
fault and conclude with
8. Check R207 and R208 (see
conclude with Step
9. Confirm the removal of the fault and go to
or the fault could not be found, replace the board and go to
Tasks" on page
10. If there is also a fault with the transmit modulation, notwithstanding
modulation at the auxiliary connector, go to
Using Auxiliary Connector" on page
go to "Final Tasks" on page
can.
with 2.4V DC offset
pp
Step
Step 6. If it is not, check the LPF circuit
Figure
9.
Step 8. If it is not, check the buffer
Step 9.
13.7). Repair any fault and
Figure
9.
163.
163.
© Tait Electronics Limited November 2007
4. If it is not, CODEC 1
"Final Tasks" on
Figure 13.7).
13.7). Repair any fault and
Figure 13.7).
Figure 13.7). Repair any
Step 10. If the repair failed
"Faulty Modulation
420. If there is no other fault,
TM8100/TM8200 Service Manual
"Final