LG GX500 Service Manual page 95

4. TROUBLE SHOOTING
GX500 Operational Description
4.12.2 Checking PLL Control signals
Checking Points
TP1 (RF_EN)
Figure 4-34. Transceiver
RF Transceiver Circuit Diagram
FE2
33
VBIAS
34
VDDTX1V5 VDDRX2V8
35 20
TX1 VDDRX1V5
36 19
TX2 VCO_RC
37 18
VDDTX2V8 VDDVCO2V8
38 17
VDDMIX2V8 EN
39 16
GND3 VDDXO2V8
40 15
FSYS1
14
GND4 GND1
41 13
Figure 4-35. Transceiver Circuit
LGE Internal Use Only
LG Electronics
TP3 (RF_CLK)
TP2 (RF_DATA)
C430 C416 C411
0.1U 0.1U 0.1U C442
0.1U
R402
820
TP1
TP1
X401
TP3
4 3
1 2
26MHz
TP
DSX321SG-26M
RF_CLK
RF_DA
TP2
QX
TP401
Q
IX
TP402
I TP2
*SIM2-> Transceiver is embeded in BB chip.
Checking Flow
EN Signal(TP1) is OK ?
Yes
DA(Data,TP2) is Normal ?
Yes
CLK(Clock,TP3) is Normal ?
Yes
Control Signal is OK.
See next page to check
Mobile SW & FEM.
Waveform
RF_DATA(TP3)
RF_EN
26MHZ_MCLK
RF_CLK(TP2)
RF_EN(TP1)
Figure 4-36. PLL Control Waveform
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Revision A
No
Check U401
Check U401
No
No
Check U401
Only for training and service purposes
LGE Property