The 220V AC input circuit and rectification filtering circuit fail to provide sufficient working voltage for the switching tube, exceeding the control range of the pulse width modulation circuit.
The load circuit has an overcurrent issue, causing an increased load on the switch-mode power supply, which in turn leads to a decrease in output voltage.
The on/off interface circuit is in a standby state, causing the switching power supply to operate at a low-frequency oscillation, with the output voltage being the same as the standby state. This type of fault should only occur in models where there is no backup power supply, and the working voltage for the CPU in standby mode is provided by the switching power supply.
The on/off interface circuit at the end was operating between the on and standby states due to an issue, resulting in the switching power supply working at a frequency between standby and on states. This caused the output voltage of the switching power supply to be higher than the standby value and lower than the on value. Aviation ground power, 36V aviation power supply, 400HZ variable frequency power supply, 115/200V power supply, 27V DC power supply, 400HZ power supply, aviation power supply.
The protective circuit terminal operates in a conductive state due to a fault, causing the power supply to enter a weak oscillation narrow pulse mode, resulting in a drop in the output voltage of the switching power supply.
The diodes and filter capacitors in the rectifying output circuit, as well as the damaged current-limiting resistors, have caused the output voltage to drop.
The PWM circuit is malfunctioning, unable to provide a proportional response to changes in the output voltage of the switching power supply. The adjustment direction and magnitude of the base voltage for the power switch tube are incorrect, resulting in a low output voltage from the switching power supply.
