Only For Training And Service Purposes - LG MG295 Service Manual

(3) Checking PAM Control Signal
TEST POINT
U500
C506
(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
Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

VBAT
C503 C504 C505
8p 33p 22u
15
DCS_PCS_OUT DCS_PCS_IN
11
U502
EGSM_OUT EGSM_IN
SKY77318
19
RSVD_GND ENABLE
21
P_GND
C507
(PAM_EN)
Graph 4.3.3
Similar? Similar? Similar?
Yes Yes Yes
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4. TROUBLE SHOOTING
CIRCUIT
C509 C510
0.01u 0.01u
4dB
R507 C512 33p
3
24 R511
4
R510
220
220
18
1
BS
C516 100p
R513
30
R512 R514
180 180
5dB
C519
39p
No No No
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S/W
R501 100ohm
PA_BAND
R502 100ohm
PA_EN
R504 1K
TX_RAMP
C506 C507 C508
39p 27p 27p
2V
U501
MC74VHC1G04DFT2G
C511
1000p 5
VCC
2 4
GND
3
R509
1M
1K
R515
C517
QP
1000p
LGE Internal Use Only