Checking Vco Block - LG U8500 Service Manual

4. TROUBLE SHOOTING

4.6.1 Checking VCO Block

TP2
TP1
TP3
TP6
TP5
R1027
24
R1032
15
R1034
51
Test Point (TXVCO Level)
TP1 TP4
TP2
925-960 MHz
C1086
1000p
L1015
9.1nH
L1028 10nH
MQW5V0C869M U1003
10 3
VC VB
1 9
OUT_GSM SW1
5 11
OUT_DCSPCS SW2
8 2
GND5 GND1
12 4
GND6 GND2
13 6
GND7 GND3
14 7
GND8 GND4
Schematic of RF TXVCO
- 88 -
TP4
TP6
TP3
R1037
82
C1083 C1085
120p 1000p
FB1000
VREG_RFTX_2.85V
R1025 100
GSM_TX_VCO_0_EN_N
R1026 100
GSM_TX_VCO_1_EN_N
VREG_MSMP_2.7V
VREG_RFTX_2.85V
TP5
38
VDDA11
39
TX_MOD_CP
40
VDDA12
41
C1084 (PPS)
TX_VCO_FB
42
22n
C1079
82p
R1036
47
R1030
51 C1076 C1081 C1072
0.1u 0.01u 22p
C1077 C1080
C1073
10u
0.1u 100p