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 the+5VSB, PS-ON, and PW-OK signals to locate the faulty area is an effective method for rapid maintenance.
5VSB, PS-ON, PW-OK control signals
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TX switching power supply relies on the combination of+5VSB and PS-ON control signals to achieve power on and off+ 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, 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 or off the power supply or for remote wake-up of the network computer. Different models of ATX switch power supplies have different standby voltage values of 3V, 3.6V, and 4.6V. When pressing the POWER switch on the host panel or remotely booting up through network wake-up, the PS-ON is grounded by the electronic switch on the motherboard after controlled startup, and a green wire is input from pin 14 of the ATX plug. PW-OK is an output signal used by the motherboard to detect the quality of the power supply. It is led out from pin 8 of the ATX plug using a gray wire. The standby state is at zero level, and the controlled startup voltage output stabilizes to 5V high level.
Offline live detection of ATX power supply: First, measure the PS-ON and PW-OK signals in standby mode. The former is at a high level and the latter is at a low level. Pin 9 of the plug outputs no other voltage except for+5VSB. The next step is to manually wake up the ATX switch power supply. Use a wire to short circuit the PS-ON signal at 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 mode to start controlled mode. At this time, the PS-ON signal is low, PW-OK,+5VSB signals are high, and the ATX plug has outputs 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.
