HF from power supply on printer frame?


today I tested the motors on my printer. While adjusting the micro switches, I mentioned some strange sensation on my arms then they were touching the printer frame - like tiny electric shocks. It seems like the whole printer frame is loaded with high frequency as soon as the power supply is connected. I checked the cabling, no short cuts to the frame, and the printer seems to be working normally as far as I was able to test it (still waiting for some missing parts…).

When I use a lab power supply, this effect seems to be not there. Do I have a faulty power supply or is this normal? Should I ground the printer frame?


I don’t have this behaviour

wtf… I really don’t know what to say to this. I don’t have that behaviour as well…
Is your printer standing in an HF laboratory with fancy equipment?

~ Tectu

That’s really strange

For my opinion, you have a lot of chance to have a defect power supply. Because as already specified, I don’t have the same behaviour with my printer. Moreover, with your lab power supply, you don’t have this problem. Why not ask a new power supply to Velleman ?

Thanks for your opinions. I will check again with the lab supply and request a new power supply if the behavior can be tracked down to the supply.

And yes - I am a HAM radio operator and in fact own some fancy HF stuff - but that had been turned off :wink:

Hi HamOP,

in that case - do you have a spectrum analyzer? A small search coil can quickly identify “bad” switching power supplies, they tend to produce lots of em-noise at certain frequencies.