Tait TM8100 mobiles Service Manual page 245

Task 42 —
CODEC 2 Circuitry
TM8100/TM8200 Service Manual
© Tait Electronics Limited November 2007
4. Replace all cans.
5. Repeat Task 40
failed, replace the board and go to
If the CCTM checks indicate a fault in the CODEC 2 circuitry or with the
digital signals to and from the circuitry, rectify the fault as follows:
1. Most of the CODEC 2 circuitry is situated under the
If not already done, remove the
2. Check the following digital signals at IC205 (see
pin 10 :
■
DIG CDC
pin 12 :
■
DIG CDC
pin 8 :
■ CDC
pin 9 :
■
DIG CDC
These signals to and from the digital board should all be active:
digital signals: 3.3 ± 0.3V
3. If the digital signals are correct, the CODEC 2 circuitry is suspect;
go to Step 6. If they are not, go to
4. If any or all digital signals are missing, check the connections between
IC205 and the digital board (see
5. If there are faults such as open circuits in the connections, repair the
circuitry and repeat
If the connections are not faulty, then the digital board is faulty.
Replace the board and go to
6. The CODEC 2 circuitry comprises IC205 and associated components
under the
CDC TOP
can (see
CDC BOT
7. Repair the circuitry. Note that, if the circuitry is functioning properly,
501 test point (see
probing the
TP
will show a five-step staircase signal followed by a random nine-step
staircase signal — this is the expected power-up auto-calibration
sequence.
8. Confirm the removal of the fault, and go to
failed, replace the board and go to
9. Replace all cans.
10. Repeat Task 40
failed, replace the board and go to
to confirm the removal of the fault. If the repair
"Final Tasks" on page
CDC TOP
2
LRCK
2
SCLK
2
DIG SDTO
2 .
SDTI
Step
Figure
Task 40.
"Final Tasks" on page
can (see Figure 9.17) as well as R246 under the
Figure 7.3 on page
Figure
"Final Tasks" on page
to confirm the removal of the fault. If the repair
"Final Tasks" on page
Frequency Synthesizer Fault Finding
163.
CDC TOP
can.
Figure 9.17):
4.
9.17).
163.
174). Locate the fault.
9.18) during power-up
Step 9. If the repair
163.
163.
can.
245