Question About Spark in Sensor GX-550 When Switching PSU On
Question About Spark in Sensor GX-550 When Switching PSU On
Hi, I noticed my PC wouldn't turn on sometimes. I tried turning off the PSU switch and then back on. During that process, I heard a popping or arching sound and saw sparks when switching the PSU to power halfway. I switched it off again quickly. After some troubleshooting, I discovered the GPU (RX 580) was shorted. Removing the GPU fixed the issue. Since my CPU has an integrated GPU, I've been using the system for a while without any problems so far. My main worry is whether the PSU is still functioning properly. Thanks.
Stop doing that. Switches for AC power such as a wall light-switch are intentionally designed with a snap-action mechanism specifically to reduce the time between open and closed + thus arcing, and by doing this you are defeating its purpose and wearing out the contacts. This is user error.
If you snap the switch quickly, it won't spark every time either, because with AC there is a goodly amount of time the voltage is near zero.
View: https://www.youtube.com/watch?v=jrMiqEkSk48
I discovered a YouTube video that resembles something similar, but my setup doesn't have proper grounding. Still, everything appears okay at the moment. Even if I change it, it no longer sparks once the GPU is removed from the system. If this was a fail-safe measure, which component of the PSU would handle that? Probably just for safety, considering a bad PSU could harm the entire PC.
The spark observed in this video stems from the initial current surge that enters an ATX PSU at switch-on. This happens because the bulk capacitor, usually rated at 420V DC, appears as a short circuit at first. The surge lasts only a fraction of a second and typically ranges between 20A and 100A. As the switch contacts close, an arc appears and a bright flash is visible.
The absence of a second flash when the PSU is briefly switched off and then restarted is due to the capacitor holding onto most of its charge, resulting in a much lower surge current.
I often notice a brief light flash when connecting laptop PSUs to mains, particularly in dark rooms—it's just the normal initial inrush charging the bulk capacitor. This flash can be seen more frequently in complete darkness.
This behavior isn't ideal. ATX PSUs are generally Class I and depend on a safety earth connection to divert dangerous currents safely to ground. Without this protection, a serious fault could cause a fuse to blow or a circuit breaker to trip. If a wire inside the PSU short-circuits and the metal casing becomes live (such as with 120V / 230V AC), it could result in a fatal electric shock.
It seems the power supply unit is still secure. The spark occurred during the halfway switch-on process.
Stop doing that. Switches for AC power such as a wall light-switch are intentionally designed with a snap-action mechanism specifically to reduce the time between open and closed + thus arcing, and by doing this you are defeating its purpose and wearing out the contacts. This is user error.
If you snap the switch quickly, it won't spark every time either, because with AC there is a goodly amount of time the voltage is near zero.
View: https://www.youtube.com/watch?v=jrMiqEkSk48
Your power supply unit seems fine, but make sure the wall outlet is properly grounded. Without grounding, other components could be at risk.