Explanation For Micom Circuit - LG LSC27931SB Service Manual

6.EXPLANATION FOR MICOM CIRCUIT

1. EXPLANATION FOR PCB CIRCUIT
1-1. Power circuit
The power circuit includes a Switched Mode Power Supply (SMPS). It consists of a rectifier (BD1 and CE1) converting AC
to DC, a switch (IC2) switching the DC voltage, a transformer, and a feedback circuit (IC3 and IC4).
Caution : Since high voltage (160 Vdc) is maintained at the power terminal, wait at least 3 minutes after unplugging the
appliance to check the voltages to allow the current to dissipate.
Voltage of every part is as follows:
Part VA1
Voltage
110~127 Vac
BD1
D3SBA60
R2(PRC)
560K
1/2W
L2
1.3A,40mH
R1(PRC)
CM2
220nF 330K, 1W
FUSE2
250V/5A
L1
7A,2mH
CM1
330nF
275VAC
VA1
SVC621-200V
(SVC331-100V)
FUSE1
JF1JF2
250V/15A
CON1
TAB1(N) TAB2(L)
2 1
POWER
CE1
160 Vdc
TRANS
D3
1 RL3
10
CM3
R3(PRC)
473
56K,2W
+16V
CE1
/630V
68uF
D1
/400V
FB1
2
FR107
12
D4
RL3
D2
R5*
FR107
68,1/8W
5
R4* CE2
CE4
6.8K 22uF
1000uF
1/8W /50V
/35V
4
4
4
1
3
8
2
IC2 R6
5
680
STR
Rocp
G6351
CC1*
0.68,1W
471
3
CC2
CE2 CE3
14 Vdc 12 Vdc
+12V
R8*
1.8K
RF2*
1/8W
9.1KF
CC30* CC31*
1/8W
104 104
IC3
CE3 1
R9*
1000uF
1K
R89* CC3*
/25V
1/8W
2
10K,1/8W
104
RF3*
IC4
KIA431 2.4KF
1/8W
The part highlighted in green, are the
components of the Switched Mode
Power Supply
- 21 -
CE4 CE5
15.5 Vdc 5 Vdc
5V
IC5
1 64 VDD
3
7805
55 Varef
2
IC1
CE5
220uF CC6*
CC4* CC5*
104
104 104 /16V
MICOM
32 Vss
54 Vass
26 TEST