Daewoo TVZ 1321, Service Manual

Page: 43 / 151

41
2-3. SMPS BASIC OPERATING DESCRIPTION
1) Power supply block circuit
2) Initial Operating Conditions
– When AC voltage is applied at PWC1, the bridge rectifier converts the output voltage to DC and is filtered by C806.
– This voltage is applied to pin 9(V in term.) of I801, through R806 thus starting the operation of I801.
– After C807 charges up to approx. 8V through series resistance R806, then the CTRL circuit starts operating.
– The time constant created by R806 and C807 determines the time delay before the CTRL circuit operation begins
after the AC power is applied. Therefore if the value of C807 is high, it could delay the starting of I801 circuit.
– CTRL circuit operation begins when drive(oscillation) at pin 3 of T801, forward biases D808 and charges C807.
– When the voltage increases at pin 4 of T801, this forward biases D807 and charges C809. When the voltage across
C809 turns off the power to T810.
– This results in the energy stored in the primary being induced into the secondary circuit.
PWC1
R804
2.2M(COMP)
1/2W
F801
AC 125V 4A
C801
O.1U(M)
AC250V
Z801
SVC2710
VARISTOR
L801
TLF-472BE
D802-D805
:1S1888
C802-C805
4700P 500V
R803
1 OHM 7W
CEMENT
R812
120K
1/2W
R806
36K
2W
8 9
10
11
12
13
14
16
15
7
6
5
4
3
2
1
R819
2.2
1/4W
R833
4.7K
1/4W
R807
18 1W
DR
S
B
C
E
OCP
1801
STR-S5707
Vin
SENSE
START UP
1
1
7
6
3
2
1
3
4
4
PRE REA
T.S.D
DSC
REF
OCP
R1 C1
C2 R2 C4 C3
PROPORTION
ORIVE
DVP LATCM
D810
BYV950
240(*200)
1/4W
R832
R809
0.27(F)
2W
R816
1K
1/4W
C822
1500P
50V
C824
4700P
AC400V
C823
3900P
630VPL
L803
MD-5
C808
220U
25V
R815
1.8K
1/4W
R813
100K
1/4W
C807
220U
25V
C809
10U
100V
D807
BYV95C
123V
15V
15V
8.5V
D811
BYV95C
D812
BYV95C
D813
BYW95C
D814
BYW95C
C827
1000P(HIKR)
2KV
T810
TSM-4242A3
C810
470U
16V
C812
470U
25V
C814
470U
25V
C828
0.01U
C815
100U
160V
D809
BYV95C
D808
BYV95C
D803
C803 D805
C805
D802
C802
D804
C804
C806
330U(LWF)
200V