Read Sharp 28JW-74H (serv.man2) Service Manual online
50Hz Widescreen Colour Television – GA20 Chassis
Sharp Electronics (UK) Ltd
Technical Support
Contents
Switch Mode Power Supply.................................................................................................................. 1
SMPS control IC ............................................................................................................................... 1
Features ........................................................................................................................................ 1
Supply (Pin 1) ............................................................................................................................ 2
Drain (Pin 8................................................................................................................................ 2
Control (Pin 3) ........................................................................................................................... 3
Burst Standby mode............................................................................................................... 3
Hiccup Mode .......................................................................................................................... 3
Demagnetization (Pin 4) ............................................................................................................ 3
Overvoltage............................................................................................................................ 3
Overpower ............................................................................................................................. 3
Current Sense (Pin 5) ................................................................................................................ 3
Short Winding Protection........................................................................................................ 3
Overcurrent ............................................................................................................................ 4
Soft Start ................................................................................................................................ 4
Drive (Pin 6)............................................................................................................................... 4
HT Regulation................................................................................................................................... 4
Standby ............................................................................................................................................ 4
Standby ............................................................................................................................................ 5
Secondary Protection........................................................................................................................ 5
Excessive EHT.............................................................................................................................. 6
CRT Heater Voltage ...................................................................................................................... 6
Horizontal Output Stage ....................................................................................................................... 7
Horizontal Drive Mute ....................................................................................................................... 7
Horizontal Output Theory.................................................................................................................. 7
Vertical Driver..................................................................................................................................... 10
Audio Output ...................................................................................................................................... 12
LOW PASS FILTER........................................................................................................................ 12
Protection ....................................................................................................................................... 13
Mute................................................................................................................................................ 14
Power On .................................................................................................................................... 14
Power Off .................................................................................................................................... 14
Off-Mute1................................................................................................................................. 14
Off-Mute 2................................................................................................................................ 14
Off-Mute 3................................................................................................................................ 14
Microprocessor................................................................................................................................... 15
Supplies.......................................................................................................................................... 15
Reset/Watchdog Circuit .................................................................................................................. 16
I
2
C Bus............................................................................................................................................ 16
Vertical Protection........................................................................................................................... 16
Safety ............................................................................................................................................. 16
LED’s .............................................................................................................................................. 17
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