TM8100 Mobile Radio
Service Manual
Diagnosis of Faults on Main Board
195
May 2004 © Tait Electronics Limited
4.
The VCXO tank circuit (Q501, D501, D502, XL501 and
associated components) or the crystal XL501 [at 5D3/5E4] is
faulty (see
). If not already done, remove the main-
board assembly from the chassis, and remove the
VCXO
BOT
can.
Locate and repair the fault, confirm the removal of the fault, and go
to Step 9. If the repair failed, return to
and replace
the complete main-board assembly.
5.
There is a fault in the CODEC 2 circuitry or with the digital
signals to and from IC205 [at 2P2/2D12]. The CODEC 2
circuitry comprises IC205 and associated components under the
CDC
TOP
can (see
) as well as R246 [at
2Q1/2C13] under the
CDC
BOT
can (see
). If not already done, remove the
CDC
TOP
can.
6.
Check the signals
DIG
CDC
2
LRCK
at pin 10 of IC205,
DIG
CDC
2
SCLK
at pin 12,
CDC
2
DIG
SDTO
at pin 8, and
DIG
CDC
2
SDTI
at pin 9 [at
2Q2]. The signals should be active 3.3 V digital signals to and
from the digital board. If the signals are correct, go to Step 8. If
they are not, go to Step 7.
7.
If any or all digital signals are missing, check the connections
between IC205 and the digital board. Repair any faults such as
open circuits, and return to Step 1. If the connections are not
faulty, then the digital board is faulty. Return to
and replace the complete main-board assembly.
8.
The CODEC 2 circuitry identified in Step 5 is faulty. Locate and
repair the fault, confirm the removal of the fault, and go to Step
9. Note that, if the circuitry is functioning properly, probing the
TP
501
test point [at 5F5/5G5] (see
) during power-up
will show a five-step staircase signal followed by a random nine-
step staircase signal — this is the expected power-up auto-
calibration sequence. If the repair failed, return to
and replace the complete main-board assembly.
9.
Replace all cans. Repeat Steps 1 to 3 to confirm the removal of
the fault. If the repair failed, return to
and replace
the complete main-board assembly.
Summary of Contents for TM8000 Series
Page 32: ...32 Introduction TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Page 78: ...78 Circuit Descriptions TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Page 106: ...106 General Information TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
Page 124: ...124 Servicing Procedure TM8100 Mobile Radio Service Manual May 2004 Tait Electronics Limited ...
