TM8100 Mobile Radio
Service Manual
Diagnosis of Faults on Main Board
239
May 2004 © Tait Electronics Limited
Task 3 —
Faulty Receiver
If the receiver does not operate, check the operation of the base-band
CODEC and receiver AGC as described below. It is assumed that the
receiver and power-supply circuitry were checked and no faults were
found.
1.
Remove the
CDC
BOT
can. With no RF signal applied, check that
the voltage at pin 14 [at 2N4/2F12] of IC201 exceeds 2.5 V DC
(see
). If it does, go to Step 4. If it does not, go to
Step 2.
2.
Check that the voltage at pin 12 [at 2N5/2F11] of IC201 exceeds
1 V DC. If it does, go to Step 3. If it does not, check for and
repair any shorts to ground at the junction of R238 [at 2N5/2F11]
and pin 12 (see
). Confirm the removal of the fault
and return to
. If the repair failed or the fault could
not be found, return to
and replace the complete
main-board assembly.
3.
Check the circuitry (R238, R239, R240) [at 2N4/2F11] around
pins 12, 13 and 14 of IC201 (see
). Repair any fault.
Confirm the removal of the fault and return to
the repair failed or the fault could not be found, return to
and replace the complete main-board assembly.
4.
Apply a strong on-channel signal. (Use the programming
application to find the frequency selected for channel 1.) Check
that a sine wave is present at the
QN
test point [at 4P1/4C12] (there
is access through a hole in the
IF
TOP
can — see
). If
there is, the digital board or IC204 is faulty; return to
and replace the complete main-board assembly. If
a sine wave is not present, go to
on the receiver.
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 ...