Basically a DVD player has three main units which work together in harmony as shown in the figure below.
We have the power board which is usually S.M.P.S but in the older ones they used to have special types of transformers with many output to supply to the other circuits.
Next to the power board we have the Loader which houses the pickup and then the Decoder (electronics board) all interconnected by use of wires (conductors) and ribbon connectors.
You can relate the actual units in the picture below, please note that the placement of these units varies with different models.
Currently most of the DVD players in the market are using switch mode power supply (S.M.P.S)
One common thing with all the switch mode power supply is that they have the primary side (HOT) and the secondary side (COLD)
The primary side includes all components from the power supply input to the input of chopper transformer down through the middle of the Opto-isolator.
The secondary side includes the output of the chopper transformer, secondary rectifier diodes, and the secondary filter capacitors for each line.
When doing voltage testing on DVD power supply, be sure to use the main capacitor negative pin as your ground when testing the primary side and on the secondary side use one of the Ground pin on the connector output or negative pin of any filter capacitor on the secondary side.
Also note that the opto-isolator has two legs on the primary side of the supply and two legs on the secondary side.
To test for voltage on this I.C be sure to use the correct ground.
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