Solved Printer Turned On by Itself

Hi Masters,

I have Robo3D R1+ on the table next to other 3D printer.
Both connected to the same power extension.
When i turned on Robo, it makes strange sound, and what surprise me is the other printer next to it is also turned on while its switch is off.

So i turned off Robo, the other printer also "automatically" off, unplugged the power cable of the other printer and then turn Robo back on, and everything is normal, no strange sound.

Is this electrical interference, grounding problem, or both or else?
Has anyone ever had same experience?

How do i fix this?

Thanks.

 

Hi Waldo,

Thanks for the reply.
Its already solved.
First i thought of the power supply too close to each other, Robo on the right, I3 Mega on the left, so i switch position but its not solving, then i change the power extension where both plugged in, and now its ok, so the problem is my power extension.