using the board with external 5v source

[johnsl]

using the board with external 5v source

[ianlee74]

That will work fine. You just need to also connect the grounds between your power supply and your printer.

[paboman]

i want to use a power bank for the 5v.
so connecting the printer metal frame to the the powerbank gnd will work ?
but the gnd of the power bank is the metal case of the usb plug or the black wire?
thx again

[ianlee74]

I wouldn't depend on the case being a good ground. You should be able to find a ground wire from your controller's power supply or a ground pin on the controller itself that you can connect the JohnSL board to.