Checking Vco Block - LG KS10 Service Manual

4. TROUBLE SHOOTING

4.6.1 Checking VCO Block

GSM_PA_RAMP
R513
VBATT
0
C543
TP2
22u
TP1
R516 15
R518 15
R522 R523
R520 R521
270
270
220 220
R524
51
LGE Internal Use Only
TP3
VREG_MSMP_2.7V
TP5
MQW5V0C869M U502
10 3
VC VB
1 9
OUT_GSM SW1
5 11
OUT_DCSPCS SW2
8 2
GND5 GND1
12 4
GND6 GND2
C554
13 6
tcc_1608h_9_r
GND7 GND3
33p
14 7
GND8 GND4
C555
0.1uF
- 104 -
R507 100
(1%)
R508
R510
C537
100
120p
C539
(1%)
5.6n
ECHU1C562JX5
TX_ON
R514 100ohm
C545
0.01u
FB502
R517
R519
C553
TX VCO CONTROL LOGIC
4.7u
C557
15p
C556
15p
GSM850/900
DCS1800/PCS1900
NO OSCILLATION
TP4
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
_
37
GSM900_I
38
(1%) VDDA11
0
39
TX_MOD_
40
C535 VDDA12
41
330p TX_VCO_F
42
C541 82p
C546
C547
1000p
100p
VREG_RFTX_2.85V
100ohm
GSM_TX_VCO_0_EN_N
100ohm
GSM_TX_VCO_1_EN_N
TP4 TP5
HIGH LOW
LOW HIGH
HIGH HIGH