Automatic degaussing each time the power is turned on, the microprocessor N101 degaussing control terminal "foot is high level. The high level is divided by R558, R557 voltage limiting current to make the excitation tube V511 turn on, 14.5V voltage through the current limiting resistor R554, relay The KY501 drive coil and the c-e pole of the V511 form a loop, so that a current flows in the KY501 drive coil, and a current generates a magnetic field on the drive coil of the KY501, so that the AC contact in the KY501 is attracted. At this time, the 220V mains voltage Using the thermal performance of the degaussing resistor PR501, an alternating magnetic field is generated in the degaussing coil, and the picture tube and its accessories are demagnetized. After 3s, the $% of the N101 pin automatically returns to a low level, V511 is turned off, and the degaussing circuit stops working. The degaussing circuit not only avoids the failure of the degaussing resistance due to overheating, but also improves the working efficiency of the degaussing circuit. Manual degaussing In the course of use, if the picture tube is magnetized due to movement or the like, the kinescope and its accessories can be demagnetized by manual degaussing. When the "degaussing" button on the panel is pressed, the foot of the N101 outputs a high-level control voltage to complete the manual degaussing process, thereby facilitating the user's use. The function of the diode VD532 is to prevent the KY501 drive coil from generating excessive high peak voltage on the c pole of V511 and causing V5ll overvoltage damage. At the instant of V511 cutoff, the induced voltage on the c-pole of V511 is looped through the VD532, R554 to 14.5V power supply, so that the spike voltage is quickly released. Start-up and oscillating circuit principle 300V voltage is divided into 3 channels for switching power supply: the first path through the switching transformer T503 primary + ~ 5 winding, sent to the switch V501 drain; the second way through the R508 current limit to the start circuit amplifier tube The c pole of V502; the third path is limited by R509.R507, and is sent to the negative pole of Zener diode ZD501 and the b pole of V502. Therefore, the e-pole of V502 outputs the startup voltage. After the voltage is limited by R511, the C513 is charged. When the voltage across C513 reaches 16V, the start circuit in the N501, - foot starts to work, and the reference voltage generator generates a 5V reference voltage. The 5V voltage is not only powered by the N501's internal oscillator, error amplifier, etc., but also by the N501. / foot output, and charge and discharge through timing components R526, C523, R533, the sawtooth wave voltage is generated on the 4th leg of N501, the sawtooth wave voltage is generated by the sawtooth wave shaping circuit, and then amplified by push-pull in N501 The driving voltage is output from the 01 pin of the N501, so that the switching transistor V501 operates in the switching state. After the switch V501 is operated, the rectification and filter circuit connected to the T503 secondary winding starts to work, providing the working voltage for the load circuit, and the T5032~3 positive feedback winding generates the induced electromotive force. The positive pulse voltage on the 3 pin is divided into two outputs: one is limited by R514, and then rectified by VD509, generating 16.5V DC voltage at both ends of C513, providing the N501 with the working voltage after completion of the startup; the other is limited by R513. After VD508 rectification, a voltage of 16.5V is generated across C514 to provide an error sampling voltage for the regulation regulator circuit. Regulator regulation circuit principle The voltage regulation circuit is completed by the error sampling circuit and the N501's 2-pin internal error amplifier, current comparator and PWM latch. When the mains voltage or load does not change, the sampling voltage of the N501's 2-pin input remains unchanged, and the driving voltage duty ratio of the N501's 23-pin output remains stable. Only when the mains voltage or load circuit changes, the N501's 45 The voltage of the foot changes under the control of the error sampling circuit, so that the duty cycle of the driving voltage of the output of the N501 is changed, so that the energy stored in the switching transformer T503 does not change with the change of the mains voltage or load, thereby achieving the stable output voltage. purpose. When the mains voltage rises or the load becomes light, the voltage at the output of the T503 rises, causing the voltage across C514 to rise. The voltage across C514 is sampled by R515, VR501, R516, so that the voltage of pin 2 of N501 exceeds 2.5V. It can be known from the working principle of UC3842 internal circuit that the error sampling voltage of the 2-pin input exceeds 2.5V, which will inevitably lead to its 89-pin output driving voltage. When the duty ratio is decreased, the on-time of the switching transistor V501 is shortened, causing the storage of the switching transformer T503 to decrease, and finally the voltage of the output terminal is lowered to a prescribed value. "Secondary" power supply and high voltage power supply circuit principle Xoceco 17YA? KNEW multi-frequency digital display, "secondary" power supply and high voltage power supply circuit with N201, switching tube V513, energy storage inductor L506 as the core of the boost power supply . The output voltage is controlled by the horizontal frequency pulse, so that different output voltages can be provided for the line output tube V402 under different line frequencies, thereby achieving the purpose of multi-frequency scanning. The specific circuit is as shown. Energy-saving control circuit principle Xoceco 17YA? KNEW multi-frequency digital display with VESADPMS standard energy-saving function, it uses the microprocessor to detect the line and field sync pulse signal settings, control the display to normal, standby, suspend and shut down 4 Ways to work. The standby state, the suspended state, and the closed state are collectively referred to as a power saving state. The DPMS is implemented by the host setting. If the keyboard or mouse has not been operated for a specified period of time, the system will set the synchronization signal in the DPMS mode to make the display in a power-saving state. The relevant circuit is as shown. When the suspend or standby state is in the suspend or standby state, the 9:; foot and <=> pins of the microprocessor N101 have no line synchronizing signal or field sync signal input, and after being recognized by the internal synchronizing signal identifying circuit, the N101 is made. The @A pin is high and the BCD pin is low. When the EFG pin is high, the V505 is still turned on, so that the picture tube filament is still powered. When the N101HIJ pin is low, V101 is turned off, and then V102 is turned off, so that the 12V power supply of the small signal circuit is cut off, and the whole machine is in a suspend or standby state. In the suspend or standby state, the PWM signal output from the N101KLM pin (indicator control terminal) is limited by R542, so that V503 is in the pulse working state, so the voltage of 6.7V passes through the orange luminous tube in the LED, c- of R539 and V503. The load of the e-pole and the 12V power supply constitutes a loop, so that the orange light-emitting tube in the indicator LED is in a blinking state, indicating that the whole machine is in a suspend or standby state. (3) Off state In the off state, N101 has no line and field sync signal input, so the N101NOP and QRS pins are low. As described above, after the N101TUV pin is at a low level, the 12V voltage disappears. When the N101WXY pin is at a low level, V504 is turned off, and V505 is turned off, so that the 6.3V power supply of the picture tube filament disappears, and the whole machine is turned off. When turned off, the duty cycle of the N101Z^_ pin output PWM is less than the suspend or standby state, so the LED goes out longer than the suspend or standby state. (Finish) Deck Crane,Marine Deck Crane,Deck Container Crane,Deck Grab Dredger Henan Weihua Heavy Machinery Co., Ltd. , https://www.hoistcrane.nl