386 CODEC and Audio Fault Finding TM8100/TM8200 Service Manual
© Tait Electronics Limited June 2006
Task 5 —
Check Speaker
Outputs
If the inputs to the audio PA are not faulty, check the speaker outputs from
the PA.
1. Check the positive and negative speaker outputs
AUD ITF SPK+ and AUD
ITF SPK– at pins 3 and 8 respectively of IC202 (see Figure 13.2):
2. If the speaker outputs are correct, go to Step 5. If they are not, go to
Step 3.
3. Check for and repair any soldering faults around IC202
(see Figure 13.2), or else replace IC202.
4. Confirm the removal of the fault and go to “Final Tasks” on
page 157. If the repair failed, replace the board and go to “Final
Tasks” on page 157.
5. With the volume at maximum, check each speaker output at pins 3
and 8 of IC202 (see Figure 13.2):
6. If the speaker outputs are correct, the fault is unknown (it could be
intermittent); replace the board and go to “Final Tasks” on page 157.
If there is no AC, go to Step 7.
7. Check that C204 and R214 (see Figure 13.2) are not faulty and are
correctly soldered. Repair any fault.
8. Confirm the removal of the fault and go to “Final Tasks” on
page 157. If the repair failed or the fault could not be found, replace
the board and go to “Final Tasks” on page 157.
pin 3 of IC202 (AUD ITF SPK+): approximately half-rail bias
pin 8 of IC202 (AUD ITF SPK–): approximately half-rail bias
pin 3 of IC202 (AUD ITF SPK+): approximately 9.5V
pp
AC
pin 8 of IC202 (AUD ITF SPK–): approximately 9.5V
pp
AC
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