LG KF350 Service Manual page 95

4. TROUBLE SHOOTING
4.14.3. Checking TX I/Q Signals
FE2
33
VBIAS
34
VDDTX1V5 VDDRX2V8
35 20
TX1 VDDRX1V5
U401
36 19
TX2 VCO_RC
PMB6272
37 18
VDDTX2V8 VDDVCO2V8
38 17
VDDMIX2V8 EN
39 16
GND3 VDDXO2V8
40 15
FSYS1
14
GND4 GND1
41 13
TP4(QX)
X400
4
GND2
1
HOT1
TP1(I)
TP3(Q)
TP2(IX)
Figure 17. TX I/Q
Checking Points
U401
Figure 18. TX I/Q
LGE Internal Use Only
C433 C434 C435
0.1u 0.1u 0.1u
C437
R410 47n
820
NX3225SA
3
HOT2
GND1 2
26MHz
BT_CLK
RF_CLK
RF_DA
QX
Q
IX
I
TP1(I)
TP4(QX)
TP2(IX) TP3(Q)
Checking Flow
Check TX I/Q Signals(TP1~TP4)
Signals are
Normal ?
Yes
TX Part is OK.
Check Base Band Circuit
or
Re-Download S/W and Cal
I
Q
I
Q
Figure 19. TX I/Q Waveform
Copyright © 2008 LG Electronics. Inc. All right reserved.
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Replace
No
Transceiver
PMB6272(U401)
TX
Only for training and service purposes