Starter Circuitry Restoration in Medical Electronic Equipment Card power supply system is also very important, in addition to the conventional switching function, the switching tube usually also plays the core role of the switching power supply gap oscillator. Such a switching power supply is called a self-excited switching power supply.
Self-excited switching power supply is mainly composed of resistance current limiting. The two ends of the resistor are connected to the 300 V DC voltage and the base of the switch tube respectively. The starting resistor in most medical equipment has a large resistance value and low power.
It is also easy to cause medical instrument circuit board failure during use. The original oscillating action will fail, resulting in the absence of a bleeder circuit in the original circuit, so that the 300vdc high-voltage power at the DC power supply terminal won’t be able to successfully discharge for a long time, which requires that Discharge the capacitor in time.
There are two main ways for the excitation switching power supply during the working process. One is that the 300vdc voltage will reduce the voltage after the current limiting effect of the resistor. The voltage and current obtained at this time can be used as the DC power supply for subsequent integrated circuits
use;
The second is that ordinary civilian electricity is reduced in voltage through the action of a resistor, and DC power is supplied by means of the rectification of a diode. During the entire work process, the resistor and the integrated block that play the role of a voltage drop are prone to failure, and then they cannot function
