Checking Pam Block - LG U8500 Service Manual

4. TROUBLE SHOOTING

4.6.4 Checking PAM Block

PAM Control Signal
TP1. GSM_PA_RAMP : Power Amp Gain Control. typically, 0.5V < Vapc < 2.6V,
TP2. GSM_PA_EN : Power Amp Enable
(Power ON : higher than 2.5V , Power OFF : lower than 0.7V)
TP3. GSM_PA_BAND : Power Amp Band Selection Control
(GSM Mode : lower than 0.7V , DCS/PCS Mode : higher than 2.5V)
TP4. +VPWR : PAM Supply Voltage Vcc higher than 3.28V
TP1
TP1
TP3
Test Point (RF Tx Level)
R1050 R1049
0 0
L1026 L1025
NA NA
C1102
68p
15
DCS_PCS_OUT
11
U1005
GSM_OUT
SKY77328
19
RSVD_GND
Schematic of PAM block
TP4
TP4 TP4
+VPWR
C1100
C1104
0.01u
68u
C1098 C1070
10u
0.01u
TP2
3
DCS_PCS_IN
4
GSM_IN
18
100 R1041
ENABLE
1
BS
R1044 100
C1103 C1101
15p 15p
- 92 -
TP2
TP3
GSM_PA_EN
GSM_PA_BAND