Only For Training And Service Purposes - LG TU550 Service Manual

4.6.1 Checking VCO Block
TP3
Test Point(TXVCO Level)
FL104
NFM21PC105B1A3
2 1
OUT IN +VPWR
4 3
G2 G1
TP5
R1014 15
R1016 15
R1018 R1019
D
R1020
270
270
220
TP6
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Only for training and service purposes

TP4
TP5
TP2
TP6
TP1
TP1
MQW5V0C869M X101
10 3
VC VB
1 9
OUT_GSM SW1
5 11
OUT_DCSPCS SW2
8 2
GND5 GND1
R1021 12 4
GND6 GND2
13 6
220
GND7 GND3
14 7
GND8 GND4
R1022
51
Schematic of RF TXVCO
4. TROUBLE SHOOTING
100
C1039
120p
TX_ON
TP4
R1012
VREG_MSMP_2.7V
100
C1503
TP2
0.01u
FB102
C1062
C1063 C1064 C1065 TX VCO CONTROL LOGIC
C1066
15p 15p
33p 4.7u
0.1uF
tcc_1608h_9_r
GSM850/900
DCS1800/PCS1900
TP3
NO OSCILLATION
- 85 -
TX_MOD_CP
40
C1040 VDDA12
R1010 41
330p
TX_VCO_FB
42
33
33p
C1045
C1043
5.6n
ECHU1C562JX5
C1048
82p
C1054
C1055
1000p
100p
VREG_RFTX_2.85V
R1015 100
GSM_TX_VCO_1_EN_N
R1017 100
GSM_TX_VCO_0_EN_N
SW2 SW1
HIGH LOW
LOW HIGH
HIGH HIGH
LGE Internal Use Only