Checking Pll Control Signal - LG KE600 - Cell Phone Service Manual

5.15.8 Checking VCTCXO Circuit
See RX Part "1. Checking VCTCXO Circuit"

5.15.9 Checking PLL Control Signal

See RX Part "2. Checking PLL Control Signal"
5.15.10 Checking TX I/Q Signals
2V7_VCXO
VCC
4
C641 C632
NA OUT VCONT
1u
3
C633 100p R620 0
2V85_RF
1V5_CORE
R622 10
C636
C637
0.1u
0.1u
Figure 14. RX I/Q Circuit
Checking Points
TX_I
(IX)
Figure 20. TX I/Q
26MHz
GND
2
R619 680
1
X601
C634
22p
C635 1000p
RX_I
RX_Q
(I) (Q)
Checking Flow
Check TX I/Q Signals
AFC
Signals are
Normal?
BT_CLK
RF_CLK
RF_DA
Yes
RX Part is OK.
Check Base Band Circuit
or
Re-Download S/W and Cal
QX
Q
IX
I
TX_I
TX_Q
TX_Q
(QX)
TX_I
TX_Q
Figure 21. TX I/Q Waveform
- 111 -
5. Trouble shooting
Replace
No
Transceiver
PMB6272(U602)
TX