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Start up Operation-7
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When the power board receives the TV_SUB_ON signal from IC8000 via pin 9 of
connector P2, it outputs 2 different voltages:
16V to the A board on pins 1, 2 and 3 of connector P2.
24/32V(*) to the LED backlight board on pins 8,9 of connector P4.
TV_SUB_ON command is carried to the primary side by PC7302. This voltage is leaded
to Q7303 whcih provide the mode change signal to pin 5 of IC7301.
Therefore the operation of the IC 7301 changes the switching frequency from standby
state to working state and output voltages rise up.
Besides the ON command is connected to the Q7202 which provide power supply VCC
of PFC circuit. The PFC starts to operate then.
Output voltages from transformer T7301 start rising up until the moment when IC7401
started to operate. This IC measures the 16V line output in the secondary side. The
output of this IC is provided by PC7301 to pin 4 of IC7301. IC7301 adjust the switching
frequency by this feedback signal.
The TV_SUB_ON signal also switches on the Q7402/03/05 to provide output voltages
(16V and 24/32V(*) ) to other boards. The 24/32V(*) is provided to the LD Board for
LED Backlight Drive. The 16V is provided to the A board.
(*)The DC level is different by the LCD panel.
: P board >
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