TM8100/TM8200 Service Manual
Receiver Fault Finding
247
© Tait Electronics Limited
June 2006
Task 8 —
Moderately Low
Sensitivity
Following the initial investigation in
, check the circuitry as follows
when the sensitivity loss is moderate.
1.
Remove the
FE
TOP
can and, if not already done, the
IF
TOP
can.
2.
Check the soldering of all the components of the front-end tuning
circuitry from
C400
to
T401
(see
3.
Check the 3V supply voltage at
L404
; use the measurement point
shown in
4.
Also check the LNA bias conditions. First measure V
c
between the
collector of
Q401
and ground (see
5.
Secondly, check I
c
. To do so, unsolder and raise one terminal of
L404
(tombstone position) (see
), connect a multimeter
between this terminal and the pad for the terminal, and measure the
current.
6.
If the checks in
to
. If there
is a fault, repair it and go to
7.
Check the signal level at the output of LO1 and continue the fault
diagnosis as in
“Power Supply for FCL” on page 227
8.
Recalibrate the receiver using the calibration application.
9.
Confirm the removal of the fault and go to
. If the repair failed, go to
V
c
: 2.7 ± 0.1V
I
c
: 10 ± 1mA
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...