392
CODEC and Audio Fault Finding
TM8100/TM8200 Service Manual
© Tait Electronics Limited
June 2006
Task 8 —
Check Signal
from CODEC
First generate an appropriate audio test signal and check whether the signal
is present at the output of the CODEC circuitry.
1.
Enter the CCTM command
400
x
, where
x
is a valid channel number.
(A suitable channel will depend on the programming of the radio.)
2.
Enter the CCTM command
21
to force unmuting of the received
audio signal.
3.
Enter the CCTM command
110 128
to set the audio level at its
midpoint.
4.
At the test set apply 60%, 1kHz modulation to the RF signal. Reduce
the volume to a minimum.
5.
Enter the CCTM command
324 r5
.
6.
Check that the received signal is present at pin 2 (
AUD TAP OUT
) of the
internal-options connector
SK102
(see
) (alternatively,
the measurement point for
CDC
AUD
TAP
OUT
shown in
).
The signal should be:
7.
If the above signal is correct, go to
. If it is not, 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
) and the link
R747
(see
). Also check the auxiliary connector itself. Repair
any fault.
9.
Confirm the removal of the fault and go to
. If the repair failed
or the fault could not be found, replace the board and go to
.
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 402
. If there is no
other fault, go to
pin 2 of internal-options connector: received signal with 2.4V DC offset
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...