LG KP260 Service Manual page 50

(4) Checking TX I/Q
TEST POINT
TP8
Figure 4.2.3
CIRCUIT
CHECKING FLOW
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Only for training and service purposes
TP7
C521
0.1u
0280101
25
RX1900B
26
RX1900
27
RX1800B
28
RX1800
U502
29
RX900B
AD6548
30
RX900
31
RX850B
32
RX850
33
GND
TP8
Check if there is
Similar?
Any Major Difference
Refer to Graph4.3.4
Re-download the Software
And calibrate
- 51 -
4. TROUBLE SHOOTING
WAVEFORM
Graph 4.3.4
TP7
QP
C519
82p
QN
0.15MM
16
VLDO2
15
VLDO1
14
VBAT
13
VDD
12
VCC_TXVCO
11
TXOP_HI
10
TXOP_LO
9
VLDO3
IP
C542
82p
IN
No
Replace U502
Yes
LGE Internal Use Only