TM8100 Mobile Radio Service Manual Diagnosis of Faults on Main Board 243
May 2004 © Tait Electronics Limited
Tas k 5 —
Faulty Speaker Audio
at Auxiliary Connector
If the receiver operates normally but there is no speaker audio at the
auxiliary connector, proceed as follows:
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%, 1 kHz modulation to the RF signal.
Reduce the volume to a minimum.
5. Enter the CCTM command 324 r5. Check that the received
signal is present with an offset of 2.4 V DC at pin 13 (
AUD TAP OUT)
of the auxiliary connector (alternatively, as
CDC AUD TAP OUT [at
2B6/2G3] at the junction of R207 and R208 — see Figure 9.32).
If it is, go to Step 6. If it is not, return to Subsection 8.1 and
replace the complete main-board assembly.
6. Remove the
CDC BOT can. Check that the voltage at pin 1 [at
2E6/2H4] of IC201 is 1.2 V, and that the voltage at pin 7 [at
2D6/2G3] is 2.4 V (see Figure 9.32). If they are, return to
Subsection 8.1 and replace the complete main-board assembly. If
they are not, go to Step 7.
7. Check the circuits involving IC201 (pins 1 to 3 and 5 to 7).
Repair any fault. Confirm the removal of the fault and return to
Subsection 8.1. If the repair failed or the fault could not be found,
return to Subsection 8.1 and replace the complete main-board
assembly.
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