Tait TM8100 mobiles Service Manual page 410

Task 8 —
Check Signal
from CODEC
410 CODEC and Audio Fault Finding
First generate an appropriate audio test signal and check whether the signal
is present at the output of the CODEC circuitry.
Enter the CCTM command 400 x, where x is a valid channel number.
1.
(A suitable channel will depend on the programming of the radio.)
Enter the CCTM command 21 to force unmuting of the received
2.
audio signal.
Enter the CCTM command 110 128 to set the audio level at its
3.
midpoint.
4. At the test set apply 60%, 1kHz modulation to the RF signal. Reduce
the volume to a minimum.
Enter the CCTM command 324 r5.
5.
6. Check that the received signal is present at pin 2 (
internal-options connector SK102 (see
the measurement point for
The signal should be:
pin 2 of internal-options connector: received signal with 2.4V DC offset
7. If the above signal is correct, go to
8. Check the components in the path from pin 13 of the auxiliary
connector SK101 to the CODEC and audio circuitry. These are
C719 and L708 (see
(see Figure 13.5). Also check the auxiliary connector itself. Repair
any fault.
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
Modulation Using Auxiliary Connector" on page
other fault, go to
CDC AUD TAP OUT
Step
Figure 13.6) and the link R747
163.
"Final Tasks" on page
© Tait Electronics Limited November 2007
) of the
AUD TAP OUT
Figure 13.5) (alternatively,
shown in Figure
8. If it is not, go to Task
Step 10. If the repair failed
"Final
Task 15 of "Faulty
420. If there is no
163.
TM8100/TM8200 Service Manual
13.4).
9.