Circuit Descriptions
6-4
Samsung Electronics
1) F/B terminal of PIC1 determines output duty cycle.
2) C-E(Collector-Emitter) of PIC2 and F/B potential of PIC1 are same.
3
Operation descriptions
1) Internal OP-Amp Ô+Õ base potential of PIC3 is 2.5V and external Ò-Ó input potential is connected with PR38 and
PR39 to maintain Vout of 5.8V. (Vout = ((PR36 x PR39) / PR39) x 2.5V)
2) If load of 5.8 V terminal increases(or AC input voltage decreases) and Vout decreases below 5.8V, then :
PIC3 ÔPÕ potential down below 2.5V --> PIC3 A-K of base current down --> PIC3 of A-K current down -->
PIC2 Diode current down --> PIC2 C-E current down --> PIC2 C-E voltage up --> PIC1 F/B voltage up -->
Out Duty up --> Transformer 1st current up --> Transformer 1st power up --> Vout up --> Maintain Vout 5.8V
3) If load of 5.8 V terminal decreases(or AC input voltage rises) and Vout rises above 5.8V, then :
Reverse sequence of the above description --> Duty down --> Vout down --> Maintain 5.8V (i.e., the feedback
to maintains 5.8V).
Œ
PR35, PR36 : Reduce 5.8V overshoot
´
PR37, PC44 : Prevent PIC3 oscillation(for phase correction)
ˇ
PC09 : Adjust feedback response rate
6-1-2 (d) Feedback Control Circuit
PIC1
STR-G6153T
OCP
DRAIN
F/B
PC09
PIC2
C
E
1st GND
A
K
PIC3
A
2.5V
K
P
PR36
PR37
PC44
2nd GND
PR38
PR39
PR35
PC34
5.8V
PL34
PD33
PE33
Trans
GND
%
!
@
#
$
VCC
Fig. 6-8
Summary of Contents for DVD-739
Page 23: ...Reference Information 2 16 Samsung Electronics MEMO ...
Page 25: ...Product Specification 3 2 Samsung Electronics MEMO ...
Page 29: ...Operating Instructions 4 4 Samsung Electronics MEMO ...
Page 77: ...Exploded Views and Parts List 8 6 Samsung Electronics MEMO ...
Page 87: ...Block Diagrams 10 2 Samsung Electronics MEMO ...
Page 89: ...PCB Diagrams 11 2 Samsung Electronics 11 1 Main COMPONENT SIDE SOLDER SIDE ...
Page 90: ...PCB Diagrams Samsung Electronics 11 3 11 2 Jack ...
Page 91: ...PCB Diagrams 11 4 Samsung Electronics 11 5 Deck 11 4 Play 11 3 Power ...
Page 92: ...Samsung Electronics 12 1 12 Wiring Diagram JACK PCB MAIN PCB DECK PCB PLAY PCB POWER PCB ...
Page 93: ...Wiring Diagram 12 2 Samsung Electronics MEMO ...
Page 95: ...Schematic Diagrams 13 2 Samsung Electronics 13 1 S M P S ...
Page 96: ...Schematic Diagrams Samsung Electronics 13 3 13 2 Main Power Supply ...
Page 97: ...Schematic Diagrams 13 4 Samsung Electronics 13 3 Main Micom ...
Page 98: ...Schematic Diagrams Samsung Electronics 13 5 13 4 Servo ...
Page 99: ...Schematic Diagrams 13 6 Samsung Electronics 13 5 Video Y Output C Output CVBS Output ...
Page 100: ...Schematic Diagrams Samsung Electronics 13 7 13 6 Audio ...
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Page 108: ...Schematic Diagrams Samsung Electronics 13 15 13 14 Karaoke Power ...
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