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4. TROUBLE SHOOTING
TX Trouble
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
U401
SW401
U103
X101
FL401
TP3
TP1
TP2
TEST POINT
7
GSM_RX
NC
18
21
PGND
TX_EN
4
1
VBATT
VLOGIC
2
3
VRAMP
PCS_IN
19
6
PCS_RX
17
11
ANT
5
BS
GND1
8
9
GND2
10
GND3
GND4
12
13
GND5
GND6
14
15
GND7
GND8
16
GND9
20
GSM_IN
(50V,J,NP0)
(50V,J,NP0)
(50V,J,NP0)
(2012)
(16V,K,X7R)
(10V,Z,Y5V)
C405
33p
1K
R405
39p
C409
39p
C406
C411
18p
SKY77517
U401
C404
0.01u
VBAT
C408
39p
12p
C403
C401
10u
C410
39p
VLOGIC
DCS_PCS_OUT
GSM_OUT
BS
TXON_PA
TX_RAMP
CIRCUIT
H(2.7V)
H(2.7V)
VLOGIC (TP1)
H(2.7V)
L
BS (TP3)
H(2.7V)
H(2.7V)
TXON_PA (TP2)
PCS1900
TX
GSM850
TX
Mode
Signal configuration
Check Control
Signals(TP1,2,3)
Signals are
Normal ?
Check
ULC2(U103)
Yes
No
PAM Control Signal
is OK.
See next page to
check
Mobile SW Circuit.
CHECKING FLOW
TP2
TP1
TP3