LG KE800 Service Manual page 66

4.19.4 Checking PLL Control signals
Checking Points
RF_DATA
U501
U501
U501
RF_CLK
Figure 6. Transceiver
RF Transceiver Circuit Diagram
FE2
33
VBIAS
34
VDDTX1V5 VDDRX2V8
35
TX1 VDDRX1V5
U501
36
TX2 VCO_RC
PMB6272
37
VDDTX2V8 VDDVCO2V8
38
VDDMIX2V8 EN
39
GND3 VDDXO2V8
40
FSYS1
GND4 GND1
41
Figure7. Transceiver Circuit
RF_EN
1V5_RF 1V5_RF 2V85_RF
C515 C551 C516 C517
0.1u 0.1u 0.1u NA
20
19
18
R502 820
17
16
15
14
13
2V7_VCXO
X501
3 1
OUT VCONT
4 2
VCC GND
C529
26MHz
0.1u
Checking Flow
EN Signal is
OK ?
Yes
DA(Data) is
Normal ?
Yes
CLK(Clock) is
Normal ?
Yes
Control Signal is OK.
See next page to check
Mobile SW & FEM.
2V7_VCXO
C518
0.1u
Figure 8. PLL Control Waveform
- 67 -
4. Trouble Shooting
No
Check U501
No
Check U501
No
Check U501
Waveform
RF_EN
RF_CLK
RF_DATA