Electrically noisy ATX PC power supply

[rea5245]

Hi,

I'm using an ATX power supply to power my project. I was struggling with spurious (but oddly regular) glitches on some signal lines. After eliminating everything else, I finally disconnected the power supply and put a scope on its unloaded 5V line. The image below is what I saw. (This is even with the PSU's fan not running, because there's so little load.)



It looks like the the same frequency as the glitches on my signals.

Should I just put big capacitors on it, or is there no hope for this PSU?

Thank you.

[tunk]

I think the ATX specs says max 50mV ripple.
You could try to put some load on it.
Or, either you have a low quality PSU, and/or there's something wrong with it.
You could open it and test the output capacitors.

[Niklas]

It is probably both more effective and easier to put a ferrite clip on around the wires between the power supply and your electronics. If you have single wires it would also be possible to wind them in opposite directions on a ferrite toroid. Both options would form a common mode choke and it can work together with capacitors on the input of your electronics to filter this noise.

[NiHaoMike]

What brand is it? Many of the off brands are very poor quality.

[rea5245]

What brand is it? Many of the off brands are very poor quality.

The brand is GameMax. I bought it through Amazon. I contacted Amazon, and they're replacing it under warranty.