LG PRADA KE850 - Page 100

5. Trouble shooting
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5.13.4 Checking PLL Control signals
Checking Points Checking Flow
R416 (RF_EN)
R422 (RF_CLK) R424 (RF_DATA)
U404
Check U404
Yes
No
No
Yes
Control Signal is OK.
See next page to check
Mobile SW & FEM.
No
Yes
Check U404
Check U404
EN Signal is OK?
DA(Data) is Normal?
CLK(Clock) is Normal?
RF Transceiver Circuit Diagram Waveform
Transceiver
NA
C446
11
XO XOX
12
VCO_RC
18
VDDDIG1V5
8
VDDDIG2V8
VD
19
VDDRX1V5
VDDRX2V8
20
17
VDDVCO2V8
15
VDDXO2V8
FSYS1
14
FSYS2
10
9
FSYS3
13
GND1
MB6272
U404
7
CLK DA
6
EN
16
10p
C440
C442
0.1u
R424 0
C445
NA
0R422
0
R418
470pC433
C444
100p
R414 820
26MHz
X401
2
GND
3
OUT
VCC
4
VCONT
1
R421 0
VRF2V7
R417 1.8K
CLK
DA
26M_BB
AFC
RF_EN
RF_CLK
RF_DATA
Figure 7. Transceiver
Figure 8. Transceiver Circuit
Figure 9. PLL Control Waveform