Haier 21F8D-S Service Manual - Page 26

Adjustment

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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 (2SC4236). 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 and filtered via VD515 and C542 to obtain +25V direct current voltage to supply the vertical scan IC. The pulse voltage output from (14) is rectified and filtered via VD513 and C532 to obtain +15V direct current voltage. +12V direct current voltage output from N506 (3), after rectification of the secondary source, +9V and +5v are supplied to the decoder chip. And CPU. The voltage of VT comes from the main voltage. Adjustment 12. Adjustment The chassis of this TV set uses Toshiba IC with the latest digital bus processing technology. The adjustment points are fewer and the adjustment is simpler. The adjustment method is as follows: 26

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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 (2SC4236). 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 and filtered via
VD515 and C542 to obtain +25V direct current voltage to supply the vertical scan IC. The pulse
voltage output from (14) is rectified and filtered via VD513 and C532 to obtain +15V direct
current voltage. +12V direct current voltage output from N506 (3), after rectification of the
secondary source, +9V and +5v are supplied to the decoder chip. And CPU. The voltage of VT
comes from the main voltage.
Adjustment
12.
Adjustment
The chassis of this TV set uses Toshiba IC with the latest digital bus processing technology. The
adjustment points are fewer and the adjustment is simpler. The adjustment method is as follows:
26