LG GD310 Service Manual page 93

5. TROUBLE SHOOTING
5.12.4. Checking RX I/Q Signals
C404
100n
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
X400 NX3225SA
4
GND2
1
HOT1
TP4(QX) 26MHZ
TP1(I)
TP3(Q)
TP4(QX)
TP2(IX)
TP1(I) TP3(Q)
TP2(IX)
Figure 12. RX I/Q Circuit
Figure 13. RX I/Q
LGE Internal Use Only
C432 C419 C418
100n 100n 100n
C406 47N
R403
820
C4
3
HOT2
2
GND1
BT_CLK
RF_CLK
RF_DA
QX
Q
IX
I
Checking Points
TP4(QX) TP4(QX)
TP1(I) TP1(I)
TP3(Q) TP2(IX) TP3(Q) TP2(IX)
U400
Checking Flow
Check RX I/Q signals(TP1~TP4)
Signals are
Normal?
Yes
RX Part is OK.
Check Base Band Circuit
or
Re-Download S/W and Cal
I
Q
I
Q
Figure 14. RX I/Q Waveform
- 94 - Copyright © 2009 LG Electronics. Inc. All right reserved.
N
Replace
Transceiver
PMB6272(U400)
RX
Only for training and service purposes