Only For Training And Service Purposes - LG KG290 Service Manual

4. TROUBLE SHOOTING
(3) Checking PAM Control Signal
TEST POINT
C506
(PAM_EN)
C505
(TX_RAMP)
Figure 4.3.3
Waveform
Checking Flow
Check TX_RAMP and PAM_EN
Check if there is
Any Major Difference or not Any Major Difference or not
Refer to Graph 4.3.3
LGE Internal Use Only
VBAT
C502 C503 C504
u 18p 33p 22u
U500
15
DCS_PCS_OUT
11
EGSM_OUT
SKY77318
19
RSVD_GND
21
P_GND
Graph 4.3.3
Go to Next Step
- 66 -
CIRCUIT
C508 C509
0.01u 0.01u
4dB
R507 C511
3
DCS_PCS_IN
24 R509
4
U500 R508
EGSM_IN
220
220
18
ENABLE
1
BS C513 10p
R511
30
R510 R512
180 180
5dB
No No No
Similar? Similar? Similar?
Yes Yes Yes
Copyright © 2007 LG Electronics. Inc. All right reserved.
R500 100ohm
R501 100ohm
R503 68
C505 C506 C507
68p 27p 27p
C543
1000p
33p
MC74VHC1G04DFT2G
QP
C514
39p
QN
Re-dow nload
S/W

Only for training and service purposes

PA_BAND
PA_EN
TX_RAMP
U502
5
VCC
2
GND
3
C5
0.