Amtran LE42Z300R3D_LC420EUG-RDF1-7R1 (CN), Service Manual

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CONFIDENTIAL – DO NOT COPY Page 8-1
File No.SG-0000040
Chapter 8 Theory of Circuit Operation
The HAIER LE42Z300R3D model is a multi-frequency and multi-mode color TFT LED TV. It does not only support the VGA
、
component
、
AV and HDMI, but also support the multimedia
、
AV out and the Ethernet.
The below section discuss the main part circuit of the TV main board.
5V transfer circuit
This circuit determines whether the +5V turn on or turn off:
DC ON (+5V on): OPWRSB=Low ->Q3 turn off->Q2 turn on->U2.s>U2.g->U2 turn on-> U2.8=5V;
DC OFF (+5V off): OPWRSB=High ->Q3 turn on->Q2 turn off->U2.s=U2.g->U2 turn off-> U2.8=0V;
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