
TP9100 Service Manual
CODEC and Audio Fault Finding
287
© Tait Electronics Limited
May 2005
12.6 Faulty Modulation Using Accessory Audio Tap In
Introduction
This section covers the case where the transmitter operates normally but
there is no modulation from
AUD TAP IN
(although there is modulation at the
accessory connector). There are two tasks:
■
Task 15: check
AUD
TAP
IN
path
■
Task 16: check audio and modulation
If there was also a fault with the speaker audio at the accessory connector, it
is assumed that this has now been rectified.
Task 15 —
Check
AUD
_
TAP
_
IN
Path
To check the
AUD TAP IN
path:
1.
Check the connector
PL1
(see
) and the flexible acces-
sory board connection to the main board as defined in
. Assuming this is correct, proceed to
2.
Check the DC offset voltage at pin 8:
3.
If the offset is correct, go to
. If the offset is not correct go to
4.
Check and repair the components and soldering around
PL1
,
E902
,
and
C911
(see
).
5.
Confirm the removal of the fault and go to
. If the repair failed, go to
.
6.
Check for and repair any soldering faults around
IC205
and
R241
(see
7.
Confirm the removal of the fault and go to
. If the repair failed, go to
.
8.
Check the DC offset voltage at pin 3 of IC205:
9.
If the offset is correct,
IC205
is okay but there is a fault between
IC205 and PL1. Recheck soldering and components
R241
(see
E902
,
C911
(see
). If the offset is not
correct, replace IC205.
10.
Confirm the removal of the fault and go to
. If the repair failed or the fault could not be found, replace
pin 8 of PL1: approximately 1.5V DC offset
pin 3 of IC205: approximately 1.5V DC offset
Содержание TP9100
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Страница 294: ...294 Spare Parts TP9100 Service Manual Tait Electronics Limited May 2005 ...
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