TM8100 Mobile Radio
Service Manual
Diagnosis of Faults on Main Board
215
May 2004 © Tait Electronics Limited
Task 6 —
Check Biasing
of First PA
Check the biasing of the first PA (Q310).
1.
Use a multimeter to measure the voltage at pin 14 of IC301 [at
3G1/3C6] (see
). The voltage will be 40 ± 5 mV.
Enter the CCTM command
331
a
(where
a
was recorded in Task
5) and check that the voltage is between 2 and 5 V. Also note the
current reading; this should increase by an amount equal to the
offset noted in Step 2 of Task 5.
2.
If the voltage and current are both correct, enter the CCTM
command
331 1
to turn off final bias 1, and go to Task 7. If the
voltage is correct but not the current, go to Step 3. If neither the
current nor the voltage is correct, go to Step 5.
3.
If not already done, remove the
PAF
TOP
can. Enter the CCTM
command
331
a
(where
a
was recorded in Task 5) and check that
the voltage at the gate of Q310 [at 3F2/3D5] is between 2 and 5
V. If it is, Q310 is faulty; return to
and replace the
complete main-board assembly. If it is not, go to Step 4.
4.
Check the circuitry between pin 14 of IC301 and the gate of
Q310 (see
to
). If a fault is found, repair
it, confirm the removal of the fault, and return to
If the repair failed or Q310 itself is faulty, return to
and replace the complete main-board assembly.
5.
Use the multimeter to measure the voltage at the
FIN
1
test point [at
3J1/3C8] (see
). The voltage will be 18 ± 2 mV.
Enter the CCTM command
331
a
(where
a
was recorded in Task
5) and check that the voltage is between 1.1 and 2.7 V. If it is, go
to Step 6. If it is not, go to
on the CODEC and
audio circuitry.
6.
Check IC301 and the surrounding shaping-filter circuitry (see
). If a fault is found, repair it, confirm the removal of
the fault, and return to
. If the repair failed, return
to
and replace the complete main-board assembly.
Содержание TM8000 Series
Страница 32: ...32 Introduction TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Страница 78: ...78 Circuit Descriptions TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Страница 106: ...106 General Information TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Страница 124: ...124 Servicing Procedure TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Страница 164: ...164 Servicing of Control Head TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
