Samsung DVD-812 Service Manual page 49

Circuit Descriptions
5-1-2 (d) Feedback Control Circuit
◆ Operation descriptions
1) Internal OP-Amp '+' base potential of PICS2 is 2.5V and external "-" input potential is connected with PRS33
and PRS34 to maintain Vout of 5.8V.
2) If load of 5.8V terminal decreses (or AC inout voltage increases) and Vout increases over 5.8V,
Then : PICS2 Vs potential up over 2.5V --> PICS2 Vc down --> PICS1 A-K potential down --> PICS1 C-E current
up --> PQR12 base current up --> PQR11 base current down --> Vout down --> Maintain 5.8V
- PRD31, PRD32 : Reduce 5.8V overshoot.
- PRS32, PCS32 : Prevent PICS2 oscillation (for phase correction).
5-4
Fig. 5-9
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