Samsung BD-E8900, Service Manual

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6. Schematic Diagrams
3) IC1S01 Vcc circuit
a) ICIS01, RIS05, RIS07,RIS08 : ICIS01 driving resistance (ICIS01 works through driving resistance at power cord in)
b) ICIS01 Vcc : RIS05, RIS07, RIS08
i) Use the output of transformer as Vcc, because the current starts to flow into transformer while ICIS01 is active
ii) Rectify to DIS07 and smooth to CIS09.
iii) Use the output of transformer as ICIS01 Vcc : The loads are different before and after ICIS01 driving. (Vcc of ICIS01 decreases below OFF voltage , using only the resistance dut to lode increase after ICIS01 driving.)
4) Feedback Control Circuit
a) F/B Terminal of IC1 determines output duty cycle.
b) C-E (Collector-Emitter) of and F/B potential of PQIZ1 are same.
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