Ok, when I turn on my house fan my ender 3 goes to its main menu this is very interesting, the fan is some old house fan that does NOT use a remote so that proves there is no interference I’m confused.
What sort of fan? Some motors put out a big magnetic field when they are starting up underload. Is it a touch screen on that printer?
Within the main menu, put the cursor on Prepare, then turn on the fan. Does it advance to the Prepare menu?
I’m just trying to confirm that it is the control button press that’s being activated.
There are basically two possiblities:
the pull-up resistor (or pull-down, depending on the design) is not small enough. It’s supposed to hold the processor’s input pin either high or low while the button is not being pressed. The value is supposed to be low enough to create a current loop that shunts more current than can be induced by an electromagnetic pulse from an external source (ie. electrical noise).
The fan is creating a pulse on the AC line that is passing through the printer’s power supply and into the controller.
There are filters you can buy that remove the noise. Ideally such a filter should be put on the fan or as close to the noise source as possible. If that’s not feasible, it can be put on the printer’s power supply if it’s entering the printer via the AC line.
If it’s being induced into the switch input because the pull up/down resistor is too large, you’d have to check the firmware to verify that the internal pull-up/down resistor is being activated (it’s optional) and if it is, and it’s not enough, you can add a 1K ohm resistor between the signal input and either Vcc or Gnd, depending on whether it’s a pull-up or pull-down design.
Pull-up is most common, by the way, so if in doubt, try that.
A third alternative would be to put either the fan or the printer on a different phased outlet. We have a two-phase residential power system in North America. Typically half your outlets are on one phase and the other half are on the other. As long as a noisy device is on a different phase than an overly sensitive device, they will usually be OK. This applies only if the interference is coming into the printer via the AC line.
If the interference is being induced into the control switch input, try re-orienting the printer, moving it somewhere else, farther away from the fan.
Ill go try that idea talk soon