Check Signal From Codec - Tait TM9100 Service Manual

First generate an appropriate audio test signal and check whether the signal
Task 8 —
Check Signal
is present at the output of the CODEC circuitry.
from CODEC
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TM9100 Service Manual
© Tait Electronics Limited August 2005
Enter the CCTM command 400 x, where x is a valid channel number.
(A suitable channel will depend on the programming of the radio.)
Enter the CCTM command 21 to force unmuting of the received
audio signal.
Enter the CCTM command 110 128 to set the audio level at its
midpoint.
At the test set apply 60%, 1kHz modulation to the RF signal. Reduce
the volume to a minimum.
Enter the CCTM command 324 r5.
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
If the above signal is correct, go to
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 Figure
(see Figure 13.5). Also check the auxiliary connector itself. Repair
any fault.
Confirm the removal of the fault and go to
or the fault could not be found, replace the main-board assembly and
go to "Final Tasks" on page
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 "Final Tasks" on page
AUD TAP OUT
Figure 13.5) (alternatively,
shown in
CDC AUD TAP OUT
Step 8. If it is not, go to
13.6) and the link R747
Step 10. If the repair failed
147.
Task 15
394. If there is no
147.
CODEC and Audio Fault Finding
) of the
Figure 13.4).
Task 9.
of "Faulty
383