Haier HT-3768 Service Manual page 19

brightness signals including compound sync signals are transmitted to the
internal sync segregation circuits, where horizontal sync and vertical sync pulses
are segregated. R321 (10K), R462 (12K) C452 (3900pF) VD436 and T402 are
connected to N204 (13) are phase-lock loop filters. Horizontal pumping signals
are transmitted from (13) of N204 to horizontal promotion transistor V444
(2SC2383), and then drive the H-DRIVE transformer. After being amplified
through it switches power transistor V411 (2SD2499) to control the horizontal
scan of the electronic-beam.C412 is a horizontal S correction capacitor and L414
is for horizontal linear inductor. T402 is a horizontal output transformer. The
horizontal return pulse output from (8) of T402 is transmitted to pin (27) of N204
who controls ABL circuits. ABL avoid high-voltage over rated value that will cause
X-ray and affect your health.
5. Analysis of video amplifying circuits
The video amplifying circuits are comprised of V601, V611, V621 and peripheral
components. B, G and R signals output from N204 (50), (51) and (52), 3 video
power transistor are available for amplifying the input R, G, B. White balance
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adjustment is completed through N901 under control of an I C serial bus control
system.
6. Analysis of switching mode power circuits
The installed switching mode power source is a typical autonomous pulse switch
power source. The circuits are comprised of switching transistor V513, switching
mode transformer T501, bridge-rectifier components. When the switch is set to
on, the pulse voltage of the 220V voltage rectified by VD501 rectifier is filtered by
the capacitor C507 (150uF) to obtain +300V direct current, which is added
through (3)-(4) of the switching mode transformer T501 to the collective polar of
switching transistor V513 (2SC4584). V503, Primary coil 3-7 and feedback coil
1-2 form a self-actuated oscillator. When the appliance is first switched on.
Some 560Vp-p voltage oscillating pulses will come into being and the duty ratio is
controlled by C515. The shut down time of V513 is controlled by V512. The
current passed V512 is larger and the operating time of V513 is shorter and the
output voltage is smaller. The coupler VD515 (PC817B inlet) functions to control
voltage, and the voltage tolerance information from RP501 and V506 are
transmitted to V501 to control the switch velocity and hold the output voltage
normal.
The pulse voltage output from the secondary (12) of the switching mode
transformer T501, rectified and filtered by VD556 and C563 is +110V direct
current voltage which is the main voltage. The pulse voltage output from (13) is
rectified and filtered by VD555 and C561 and the resultant +180V direct current
voltage is supplied. The pulse voltage output from (16) is rectified and filtered by
VD516 and C552 and the resultant +19V direct current voltage is supplied to the
sound power amplifying circuits. The pulse voltage output from (15) is rectified
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