LG U990 Service Manual page 108

4.6.3 Checking PAM Block
14
GND6
13
GND5
12
VCC
U101
11 TQM7M5003
GND4
10
GND3
9
GSM_OUT
8
GND2
Test Point Net name
TP1 GSM_PA_RAMP
TP2 GSM_PA_EN
TP3 +VPWR
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Only for training and service purposes
TP2
1
DCS_PCS_IN
2
BS
3
TX_EN
4
VBATT
5
GND1
6
VRAMP
7
GSM_IN
R117 2.2K
C143
68p
TP1
GSM_PA_BAND
LOW
HIGH
Schematic of PAM Block
Test Point of PAM Block
Description
Power Amp Gain Control. Typically, 0.2 ~1.6V
Power Amp Enable (ON : >2.5V, OFF : <0.7V)
PAM Supply Voltage (Vcc > 3V)
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4. TROUBLE SHOOTING
TP3
GSM_PA_BAND R112
91
GSM_PA_EN
+VPWR
C137 C135
33u
1u
FL101
3 2
EFCH897MTDB1
G2 G1
IN
1
O1 G3
4 5
GSM_PA_RAMP
MODE
GSM
DCS/PCS
TP3
TP1
R111
DCS_PCS_TX
68
R113
10 dB
91
R114
GSM_TX
51
8 dB
R118 R119
120 120
TP2
LGE Internal Use Only