Samsung SCC-B2335, Service Manual

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Schematic Diagrams
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7-2 Power Distribution Diagram
7-2-1 Power Supply Line
1. AC 24V / DC 12V input, DC +9.6V, DC +17V, DC -11V, DC +3.3V, DC +5.0V output circuit
1) The input voltage supplied using the AC/DC adapter (AC24V / DC12V) runs through CN4 (3-4) , into the line
filter (LF1), and apply to the rectifier diode (D1 ~ D4) where it will be converted into direct voltage and
regulated by the smoothing condensers (C2, C10).
2) Then, the regulated direct voltage is applied to trans (PT1) before converted in the output voltage, each of which
outputs DC +9.6V, DC+17V, and DC -11V, respectively.
3) The conversion circuit adopts the PWM system for performance, and use FET (Q1) as a switch device.
4) The control of PWM is based on DC +9.6V, and PWM is controlled by a terminal of U1 (1) using the detection
resistance (R16 ~ R18).
5) DC +9.6V is rectified by D11, while DC +17V is rectified and output by D8.
6) If the switching waveform is decompressed on PT1-9, and rectified to D9, C16, L4 and C17, DC 7.8V will output,
which is not used in the box model. Then, D23 (UDZ9.1B) is a power protection circuit against excessive
voltage.
7) DC +3.3V and DC +5.0V are output respectively using the DC/DC conversion circuit, while the input voltage is
DC +9.6V. DC +3.3V is controlled by the detection resistances (R26, R27), while DC +5.0V is controlled by R24
and R25. The conversion circuit is BUCK-PWM.
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Power
Fig 7-1