How to quickly analyze faults in switching power supplies and repair them in a timely manner
Repairing the ATX switch power supply by starting with+5VSB, PS-ON, and PW-OK signals to locate the fault area is an effective method for rapid maintenance.
5VSB, PS-ON, PW-OK control signals
The ATX switching power supply relies on the combination of+5VSB and PS-ON control signals to turn on and off the power supply+ 5VSB is the power supply for the host system in ATX standby mode, as well as the working power supply for the circuit related to automatic management and remote wake-up communication. In standby and controlled startup modes, its output voltage is 5V high level, and a purple wire is used to lead out from pin 9 of the ATX plug. PS-ON is the control signal for the host to turn on/off the power supply or for the network computer to remotely wake up the power supply. Different models of ATX switching power supplies have different standby voltage values of 3V, 3.6V, and 4.6V. When pressing the POWER switch on the host panel or implementing network wake-up remote startup, the PS-ON is grounded by the electronic switch on the motherboard after controlled startup, and is input from pin 14 of the ATX plug using a green wire. PW-OK is an output signal used by the motherboard to detect the quality of the power supply. It is led out from the ATX plug pin 8 using a gray wire, and the standby state is at zero level. After the controlled startup voltage output is stable, it is at 5V high level.
Offline live detection of ATX power supply: Firstly, measure the PS-ON and PW-OK signals in standby mode. The former is at high level, while the latter is at low level. Plug pin 9 outputs no other voltage except for+5VSB. The second step is to manually wake up the ATX switch power supply. Use a wire to short circuit the PS-ON signal of pin 14 of the ATX plug to any ground terminal (3, 5, 7, 13, 15, 16, 17). This step is the key to detection. Wake up the ATX power supply from standby state to controlled start state. At this time, the PS-ON signal is low, PW-OK,+5VSB signals are high, and the ATX plug has an output of 3.3V, ± 5V, and ± 12V. The switch power supply fan rotates. The above operation can also be used as a method for offline power-on verification when purchasing an ATX switching power supply.
