LG FLATRON LB800H-UL, Service Manual

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EMI
COMPONENTS
LINE
100 ~ 240V
INPUT RECTIFIER
AND FILTER
ENERGY
TRANSFER
OUTPUT RECTIFIER
AND FILTER
12V
5V
GND
SIGNAL
COLLENTION
PHOTO-COUPLER
ISOLATION
PWM CONTROL
CIRCUIT
HVDC
100KHz
PRIMARY
SECONDA RY
50 ~ 60Hz
Operation description_Power
1. EMI components.
This part contains of EMI components to comply with global marketing EMI standards like FCC, VCCI CISPR,
the circuit included a line-filter, across line capacitor and of course the primary protection fuse.
2. Input rectifier and filter.
This part function is for transfer the input AC voltage to a DC voltage through a bridge rectifier and a bulk capacitor.
3. Energy Transfer.
This part function is transfer the primary energy to secondary through a power transformer.
4. Output rectifier and filter.
This part function is to make a pulse width modulation control and to provide the driver signal to power switch, to
adjust the duty cycle during different AC input and output loading condition to achive the dc output stablize, and also
the over power protection is also monitor by this part.
5. Photo-Coupler isolation.
This part function is to feed back the dc output changing status through a photo transistor to primary controller to
achive the stablized dc output voltage.
6. Signal collection.
This part function is to collect the any change from the dc output and feed back to the primary through photo
transistor