How to quickly analyze the fault of the switching power supply and repair it in time
Repairing ATX switching 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
ATX switching power supply relies on a 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 states, its output voltage is 5V high level, which is led out from pin 9 of the ATX plug using a purple wire. PS-ON is the control signal for turning on and off the power supply of the host or remotely waking up the power supply of the network computer. Different models of ATX switching power supplies have different standby voltage values of 3V, 3.6V, and 4.6V. When the POWER switch on the host panel is pressed or remote power on is achieved through network wake-up, 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 pin 8 of the ATX plug using a gray wire, and the standby state is at zero level. After the controlled startup voltage output stabilizes, it is at a high level of 5V.
Offline live detection ATX power supply, first measure the PS-ON and PW-OK signals in standby mode, with the former being high level and the latter being low level. Pin 9 of the plug does not output any other voltage except for+5VSB output. Next, the ATX switching power supply is manually awakened by using a wire to short-circuit the PS-ON signal of pin 14 of the ATX plug to any one of the ground terminals (3, 5, 7, 13, 15, 16, 17). This step is the key to detection. The ATX power supply is awakened from standby mode to start-up controlled mode, where the PS-ON signal is low, PW-OK,+5VSB signals are high, and the ATX plug has outputs of+3.3V, ± 5V, ± 12V. The fan of the switching power supply rotates. The above operation can also be used as a method for offline verification of ATX switching power supply selection.
