LG KG920 Service Manual page 83

4. TROUBLE SHOOTING
(1) Checking PAM Control Signal
TEST POINT
U501
R515(TX_RAMP)
Figure 4-16.
CIRCUIT
19
11
15
CIRCUIT
R502(PAM_EN)
RSVD_GND BS
1
ENABLE
18
SKY77328
GSM_OUT U501 GSM_IN
4
DCS_PCS_OUT DCS_PCS_IN
3
C513 C514
0.01u 0.01u
(PA)
R515
TX_RAMP
10K
C519
27p
Figure 4-17.
Check TX_RAMP and PA_EN Check TX_RAMP and PA_EN
Check if there is Check if there is
Any Major Difference or not Any Major Difference or not
Refer to Graph 6
Figure 4-18.
WAVEFORM
Graph 4-6.
R502
PA_EN
0
C508
1000p
3dB ATTEN
R507
18
R508 R509
300 300
2dB ATTEN
2V8_VEXT
R510
12
R512 R513
R514
430 430
0
No No No
Similar? Similar? Similar?
Redownload S/W
Yes Yes Yes
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(GPO_16)