There is an output voltage, but it is too high.
This fault typically originates from the voltage regulation sampling and control circuits. A closed control loop is formed by circuits such as DC output, sampling resistors, error sampling amplifiers like TL431, optocouplers, and power control chips. Any issue within this loop can lead to an increase in output voltage. Aerospace Power Supply
Insurance Burn or Explosion
Firstly, inspect the large filter capacitors, rectifier diodes, and switching transistors on the 300V circuit, as issues with the anti-interference circuit can also lead to fuses blowing and blackening. Be aware that: fuse blowouts due to switching transistor breakdown usually damage the current detection resistor and the power control chip. The negative temperature coefficient thermistor can also be easily burned out along with the fuse.
No output, fuse is normal.
This phenomenon indicates that the switch-mode power supply is not operational or has entered a maintenance state. First, measure the activation voltage of the power control chip's activation pin. If there is no activation voltage or the voltage is too low, check for leakage in the activation resistor and external components connected to the activation pin. If the power control chip is functioning normally at this point, the fault can be quickly identified through the above checks. If there is activation voltage, measure the output terminal of the control chip for high and low level changes at the moment of power-on. If there are no changes, it indicates a faulty control chip, issues with the peripheral oscillator circuit components, or problems with the maintenance circuit. In this case, replace the control chip first, then inspect the peripheral components; if there are changes, it is generally due to a defective or damaged switch tube. 36V aviation power supply
Low Output Voltage
In addition to the voltage regulation control circuit, the following reasons may also cause low output voltage:
Short circuit faults occur in the switch-mode power supply load (especially in DC/DC converters experiencing short circuits or malfunctions). At this moment, all loads connected to the switch-mode power supply circuit should be disconnected to differentiate between a fault in the switch-mode power supply circuit or the load circuit. If the voltage output is normal after disconnecting the load circuit, it indicates an overload; if it remains abnormal, it suggests a fault within the switch-mode power supply circuit.
b. Failure of rectifying diodes at the output voltage terminal and filtering capacitors can be identified through substitution methods.
c. The functional degradation of the switch tube inevitably leads to its inability to conduct normally, causing an increase in the internal resistance of the power supply and a decrease in its load-bearing capacity. 400HZ variable frequency power supply
