Checking Ant. Sw Module Block - LG U8290 Service Manual

4.4 Checking Ant. SW Module Block

GSM 900 TX
GSM 900 RX/WCDMA
DCS1800/PCS1900 TX
DCS 1800 RX
PCS 1900 RX
ANT _SEL0
ANT_SEL1
ANT_SEL2
Antenna Switch Block(Bottom)
ANT200
RF200
R221
C279
G2
ANT RF
G1
2.2nH
KMS-507
1p
L229
C283
10nH
VREG_RFRX_0_2.85V
R224
ANT_SEL2
0 C285
100p
R223
ANT_SEL1
0 C277
100p
Q507
R222
VREG_RFTX_2.85V
0 C281
100p
ANT_SEL0
UMC4N
Schematic of the Antenna Switch Block
ANT_SEL2
LOW
LOW
HIGH
LOW
HIGH
Logic Table of the Antenna Switch
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4. TROUBLE SHOOTING
TP1
TP1
33p
U207
GSM900_RX
GSM1800_RX
10
C286
VDD GSM1900_RX
0.1u
9
VC1 WCDMA
8
VC2
5
VCG
GSM18001900_TX
GSM900_TX
SFAY0004601
C284
27p
ANT_SEL1
LOW
LOW
HIGH
HIGH
LOW
1
2
3
4
12
13
ANT_SEL0
HIGH
LOW
LOW
LOW
LOW