Tait TP9100 - Page 277

TP9100 Service Manual CODEC and Audio Fault Finding 277
© Tait Electronics Limited May 2005
Tas k 6 —
Check
SUI VOL DC
Input Signal
If the output of the voice-band CODEC is correct, but the signal level does
not
vary as the volume control is varied, check the SUI VOL DC signal.
1. Check the operation of the volume pot RV 1 (see Figure 12.4) as
described in “Volume Control Faulty” on page 142.
2. Check the voltage on
TP908 (see Figure 12.2). As the volume varies,
the voltage should vary as follows:
3. If the volume varies as expected, go to Step 6. If it does not, go to
Step 4.
4. Check and repair any soldering faults around R900
(see Figure 12.4), Q910, and R953 (see Figure 12.3).
5. Confirm the removal of the fault and go to “Final Tasks” on
page 134. If the repair failed, replace the main board and go to “Final
Tasks” on page 134.
6. Remove the
CDC TOP can.
7. Check the voltage at the junction of C245 (non grounded end,
see Figure 12.3). As the volume varies, the voltage should vary as
follows.
If the voltage varies as expected, CODEC 1 (IC204, see
Figure 12.3) is suspect.
8. Replace the main board and go to “Final Tasks” on page 134.
TP908: 0.4 to 1.1V as volume varies
C245: 0.4 to 1.1V as volume varies