Only For Training And Service Purposes - LG TU550 Service Manual

4.6.4 Checking PAM Block
PAM Control Signal
TP1. GSM_PA_RAMP : Power Amp Gain Control. typically, 0.5V < Vapc < 1.6V, TP2. GSM_PA_EN :
TP3. GSM_PA_BAND : Power Amp Band Selection Control
TP4. +VPWR : PAM Supply Voltage Vcc higher than 3.5V
C1038
C1511 C1046
68p
100p
33p
C1828
0.5p
L172
L402
4.7nH
6.8nH
16
DCS_PCS_OUT
U102
10
GSM_OUT AND0041
Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

Power Amp Enable
(Power ON : higher than 2.5V , Power OFF : lower than 0.7V)
(GSM Mode : lower than 0.7V , DCS/PCS Mode : higher than 2.5V)
TP4
TP1
TP2 TP3
R1008
(1%)
2.2K
TP1
C1051
33p
C1056
51p
1
DCS_PCS_IN
7
GSM_IN
3
TX_EN
2
BS
TP3
Schematic of PAM block
4. TROUBLE SHOOTING
GSM_PA_RAMP
C1041 22n
TP4
FL104
NFM21PC105B1A3
2 1
OUT IN
4 3
C1052 G2 G1
100u
TP2
R1014 15
R1016
GSM_PA_EN
R1018 R1019
GSM_PA_BAND
270
270
- 89 -
1
IN
G2 O2
5 4
C1829
0.5p
+VPWR
MQW5V0C869M X101
10
VC VB
1
OUT_GSM SW1
15 5
OUT_DCSPCS SW2
8
GND5 GND1
R1020 R1021 12
GND6 GND2
13
220 220
GND7 GND3
14
GND8 GND4
R1022
51
LGE Internal Use Only
FL103
B7844
3
9
11
2
4
6
7