Trouble Shooting; Power On Trouble - 3.3V Main Power - LG FM300 Service Manual

4. TROUBLE SHOOTING

4.1 Power on Trouble – 3.3V Main power
Main source power of BCM5358U :
12V is Supplied From Adaptor to Modem
CN100 KJA-DC-0-0037
5
4
3
ENJW0002601
R14 100K
C18 C3
100n 1u
C8
2.2u
C15
10u
C115
DNI
LGE Internal Use Only
Passes DC/DC and 3.3V is supplied for BCM
TP1
TP1
EAH61438301
1
C106 C107 PSD24C-LF C108
DNI 0.1u 10n
ZD100
2
TP3
TP3
R102 100K
R11 100K
30
VIN5
1
FB
2
V5V
U2
3
AGND1
SC424
4
VOUT
EUSY0369702
5
VIN
6
VLDO
7
BST
C4 1u
NP_EN
VA100
4. TROUBLE SHOOTING
Q1
SI7121DN
EBK61571901
C109
DNI
R101
DNI
R8 2.7K
L100
21
LX3
20 2.2u
LX2
19
PGND6
18
PGND5
17
PGND4
16
PGND3
15
LX1
C12
31
47p
LX4
SPPH410100
ESPY0001701
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4. TROUBLE SHOOTING
EDSY0020101
C17
0.1u
C101 C102
C9
22u 22u
10n
C1
DNI
Only for training and service purposes
TP2
TP2
D1
B340A
TP4
TP4
C104
22u
C103
0.1u