LG GW520 - Qwerty Key Sense Trouble

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Copyright © 2009 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
5. Trouble shooting
GW520 service manual
5.6 Qwerty Key Sense Trouble
Start
END
Change the Dome Sheet
And check again.
Work well?
Check TP1 soldering
& signaling. OK?
Work well?
Check TP2 soldering
& signaling. OK?
Re-solder R621,R622,
R637, R639
Start
END
Change the Dome Sheet
And check again.
Work well?
Check TP1 soldering
& signaling. OK?
Work well?
Check TP2 soldering
& signaling. OK?
Re-solder R621,R622,
R637, R639
Circuit DiagramCircuit Diagram
27p
EVLC5S0250
VA402
C417
VA401
EVLC5S0250
0.1uC403
C415 27p
2V62_VIO
1uC410
R425 DNI
470
R401 4.7K
R418
C408 27p
EVLC5S0250
VA400
C404 0.1u
R400 120K
R402
4.7K
C416
27p 27pC414
C413 C412
27p 27p
P51
11
P52 P53
10
9
P54
P55
5
P56
4
3
P57
PGND
29
RESETB
27
2
SEL_28P
1
TEST
23
VDD
26
XI
XO
25
CLK_SEL
24
GND1
8
GND2
28
P10
22
7
P15
P17
6
21
P40
P41
20
P42
19
P43
18
17
P44
P45
16
P46
15
14
P47
13
P50
12
EUSY0300004
PP2106M2
U400
27pC407
C418 27p
470
R404
R419 470
470R407
R429 470
DNIC411
C419 27p
R411 470
2V62_VIO
R428 470
470R422
470R415
470R410
27pC409
R414 470
470R432 470R431
R430 470
KEY_INT
KEY_I2C_SCL
KEY_I2C_SDA
KEY_ROW0
KEY_ROW1
KEY_ROW2
KEY_ROW3
KEY_ROW4
KEY_ROW5
KEY_COL4 KEY_COL3 KEY_COL2 KEY_COL1 KEY_COL0
KEY_COL7
KEY_COL6
KEY_COL5
TP2
TP1
TP1