LG B2050 Service Manual - Page 59

Checking PAM Control Signal

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4 . TROUBLE SHOOTING (4) Checking PAM Control Signal TEST POINT Waveform 12 11 20 19 CIRCUIT VBAT C509 10p C510 33u GND9 18 GND10 GND2 10 GND1 DCS_PCS_IN 1 AND_SELECT 2 3 TX_ENABLE VBATT 4 GND 5 VRAMP 6 GSM_IN 7 RF2V85 R503 R504 36 150 [6dB] R506 R507 30 180 [5dB] R505 150 R508 180 C501 39p C504 27p C511 27p R500 15K R501 100 R502 100 RF2V85 C518 C519 0.022u 22p TX_RAMP PA_BAND PA_EN TX_RAMP PAM_EN Band Select (R501) GSM TX_Low DCS/PCS TX_High Checking Flow Graph 4-7 Check TX_RAMP and PA_EN Check if there is Any Major Difference or not Refer to Graph 4-7 Similar? Yes No Download S/W Go to Next Step - 58 -

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- 58 -
PAM_EN
TX_RAMP
TEST
POINT
CIRCUIT
Checking Flow
Waveform
Check TX_RAMP and PA_EN
Check if there is
Any Major Difference or not
Refer to Graph 4-7
Band Select (R501)
GSM TX_Low
DCS/PCS TX_High
Similar?
Yes
No
Go to Next Step
Download S/W
Graph 4-7
]
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d
6
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B
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5
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3
3
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1
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GND9
7
N
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G
10
GND1
GND10
19
20
11
GND2
5
8
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2
F
R
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(4)
Checking PAM Control Signal
4 . TROUBLE SHOOTING