24V power supply pure flat display high voltage power supply circuit diagram

Some camera CRTs use 11.4cm (4.5 inches) pure flat CRT as the display component. The anode voltage of the high-voltage component is +20kV, the focusing electrode voltage is +3.2kV, the accelerating electrode voltage is +1000V, and the power supply of the high-voltage component is DC 24V. The following circuit is designed to replace and repair the high voltage components of these monitors. The design of this circuit can also provide a reference for the design of other boost circuits.

Basic principle: NE555 constitutes a pulse generator. Adjusting the potentiometer VR2 can generate pulses with a frequency of about 20kHz, and the potentiometer VR1 adjusts the pulse width. TR1 is the driving stage, and the pulse transformer T1 uses reverse polarity excitation, that is, when TR1 is on, TR2 is off, when TR1 is off, TR2 is on, and D3, C9, VR3, R7, D4, R6, and TR3 form a high-voltage protection circuit. VR2 is used to adjust the frequency. Adjusting VR2 can adjust the high voltage.

VR2 uses precision adjustable resistors. T2 can be used alternatively with a color TV output transformer. The author chooses the line output transformer of Toyo SE-1438G series 35cm (14 inches) color TV. The anode voltage of this transformer can reach 20kV. Then the resistance value of R8 is appropriately selected to make the accelerating electrode voltage +1000V, and the resistance value of R9 makes the focus The pole voltage is +3.2kV. The entire component is packaged in an aluminum box, and the aluminum shell is grounded, which can reduce interference to the circuit.