LG KE800 Service Manual page 69

4. Trouble Shooting
4.19.6 Checking RX I/Q Signals
R502 820
DTX2V8 VDDVCO2V8
17
DMIX2V8 EN
16
D3 VDDXO2V8
15
FSYS1
14
D4 GND1
13
2V7_VCXO
X501
3
OUT VCONT
4
VCC GND
C529
26MHz
0.1u
2V85_RF 1V5_CORE
R510
10
C538 C539
0.1u 47n
Figure 13. RX I/Q Circuit
Checking Points
IX I
Q
QX
U501
Figure 14. RX I/Q
C521 820p
C528
NA
R508
1
620
2
C533
22p
C536 C537
NA NA
C552
NA
Checking Flow
RF_EN
26MHZ_MCLK
Check RX I/Q Signals
AFC
Signals are
RF_CLK
RF_DA
Normal ?
Ye s
BT_CLK
RX Part is OK.
QX
Check Base Band Circuit
Q
or
IX
Re-Download S/W and Cal.
I
I
Q
I
Q
Figure 15. RX I/Q Waveform
- 70 -
Replace
No
Transceiver
PMB6272(U501)
RX