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Level 3 Service Manual
1.
Remove
2.
Place UUT into manual test mode,
then enter
mode),
(TX level), and
3.
PA_B+ signal modulated byDM_CS
(approximately
present on
Negative bias (approximately
-3V P-P
N
Figure 21. Low Transmitter Power
6881036B20
M
U300
.
9823#
(change GSM/DCS
11062#
1215#
(GSM ARFCN),
310#
(Pseudo-random TX).
3V P-P@ 217 Hz
) is
U300 Pin 13
?
YES
YES
U300
) is present on
Pin 2
Pin 8
and
?
NO
NO
-5V
is present on
Q370 Pin 1
?
YES
NO
Correct signal is
U390
present on
Pin 7
?
YES
Q370 Pin 1,
Check
Pin 2
Pin 3
, and
See Note 1
MOTOROLA CONFIDENTIAL - PROPRIETARY
O
1.
DM_CS is present on
NO
U800
No: check
.
See Note 1
2.
Correct control signal is
Q380 Pin 4
present on
1.
U300
Replace
.
2.
Check for intermittent
fault
See Note 1
5V
U903 Pin1
-
is present on
U903
U904
No: check
and
Q370
R103
Yes: check
and
See Note 1
U390
U200
Check
and
See Note 1
November 20, 2000
In most cases, a reference board can be
used to compare signals.
Q381
?
NO
Replace
Q381
?
YES
Is PA_B+ present on
Q380 Pin 5
Pin 8
and
Q380
No: replace
?
.
.
Note 1: Check components for correct
orientation, cold solder joints, physical
damage, and functionallity.
Troubleshooting
?
000780-O
37
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Table of Contents
Troubleshooting
