Tait TM8100 mobiles, Service Manual

Page: 161 / 620

TM8100/TM8200 Service Manual Servicing Procedures 161
© Tait Electronics Limited November 2007
Task 9 —
Check the Transmit
and Transmit-Audio
Functions
If the radio does not transmit, this can be caused by:
■
the synthesizer not being in lock
■
no or wrong carrier power
■
no modulation.
If the cause is already known, go directly to the relevant fault-finding
section.
Caution
Observe the servicing precautions for transmitter
issues listed
on page 113 .
1. Use CCTM command 101 x y 0 to set the transmit frequency to the
bottom of the band.
2. Use CCTM command 33 to set the radio to transmit mode.
3. Use CCTM command
72
to read the lock status.
4. If the synthesizer is in lock, go to Step 5 . If the synthesizer is not in
lock, repair the radio as described in “Frequency Synthesizer Fault
Finding” on page 185 .
5. Repeat Step 1 to Step 4 with the transmit frequency set to the top of
the band.
6. Use CCTM command
326 1
to set the power level to very low.
7. Connect a power meter and measure the transmit power.
8. If the carrier power is correct, go to Step 10 . If the carrier power is
not correct, try to re-calibrate the radio.
9. If the re-calibration repairs the fault, go to “Final Tasks” on page 163 .
If it does not, repair the radio as described in “Transmitter Fault
Finding (>25W)” on page 267 and “Transmitter Fault Finding
(25W)” on page 341 .
10. Repeat Step 6 to Step 9 with the power level set to high ( 326 4 ).
11. Check whether the speaker is the source of the fault, as described in
“Speaker Faulty” on page 440 (graphical display) or “Speaker Faulty”
on page 454 (1-, 2- or 3-digit display).
12. If the radio transmits audio now, the original speaker was faulty.
Reassemble the radio and go to
“Final Tasks” on page 163 . If the
radio still fails to transmit, reconnect the original speaker and go to
Step 13 .
13. After having eliminated the synthesizer, the transmitter circuitry, and
the speaker as cause for the fault, repair the radio as described in
“CODEC and Audio Fault Finding” on page 399 .