The key to a switching power supply lies in its ability to oscillate normally at the startup point. This startup point refers to the PN voltage (230VDC) that enables the MOSFET driver IC Board of the switching tube to function normally.
Test Method: Remove the fuse at the upper left corner of the mainboard and connect the simulated load resistor board (this board can be homemade: simply add a few resistors to the mainboard's power output terminals, such as a 2K/1W resistor between 24V - COM, and a 1K/1W resistor and an LED in series between +5V - GND, which serves as a power indicator).
Apply a voltage regulator to the switch-mode power supply's input P and common negative terminal N, adjusting it to around 230VDC, and observe if the power indicator light on the simulated load board illuminates.
Proper operation of a switching power supply requires the addition of a load, but it cannot be directly tested with a CPU board. The purpose of adding a simulated load is to prevent the CPU from being damaged due to excessive voltage from the power supply, or for the switching power supply to malfunction due to a CPU board fault.
The KVF+415GR switch power supply has a designed startup voltage of 230VDC, but there may be deviations during actual operation, which will not exceed ±30VDC. If it exceeds this range, long-term operation can damage the power supply and other components.
