Tait TM8100 mobiles Service Manual page 418

Task 13 —
Check 2.3V Supply
Task 14 —
Check Bias Network
418 CODEC and Audio Fault Finding
If the signal is not as expected, the 2.3V supply needs to be
CH MIC AUD
checked.
1. If not already done, remove the
2. Check the voltage across C202 (see
voltage across C202: 3V
3. If the above voltage is correct, go to
4. Check the soldering of R209, and check for shorts to ground at C202
(see Figure 13.9). Repair any fault.
5. Confirm the removal of the fault and go to
page 163. If the repair failed or the fault could not be found, replace
the board and go to
If the signal at the 503 test point is incorrect, but the other checks in the
TP
above tasks reveal no fault, check the bias network.
1. Remove the
CDC TOP
2. Check the voltage at the junction of R229 and R232
(see Figure 13.10):
junction of R229 and R232: 1.5V DC
3. If the voltage is correct, go to
4. CODEC 1 (IC204) is faulty; replace the board and go to
Tasks" on page
5. Check the soldering of R229 and R232, and check for shorts across
R232 (see Figure
6. Confirm the removal of the fault and go to
page 163. If the repair failed or the fault could not be found, replace
the board and go to
CDC BOT
Figure
Task
"Final Tasks" on page
can.
Step 4. If it is not, go to
163.
13.10). Repair any fault.
"Final Tasks" on page
© Tait Electronics Limited November 2007
can.
13.9):
14. If it is not, go to Step
"Final Tasks" on
163.
Step 5.
"Final
"Final Tasks" on
163.
TM8100/TM8200 Service Manual
4.