The printer lcd is getting power from the raspberry pi usb when plugged in . Is there a way so it only has power when I have the printer itself turned on?
You could try the uhubctl code to programmatically turn off all four of the Type A connectors on the Pi. You could use my own USBControl plugin to do the same.
You could attempt to add tape to the 5V pin on that connection. (Search the forum here for the many times this has been suggested.)
What I find easiest though is to use an Ikea KOPPLA (search the forum for that) and a TP-Link SmartPlug, powering both on/off together.
My time again \o/ 
You can put some tape over the 5V pin of your usb connector.
Then your printer can't power from your pi and this shouldn't happen again even if you power on your pi first.
(pin 1 is 5V)
1 Like
If you do, then maybe add a photo of how to apply the tape because I have read this advice a couple of times and am still wondering how to do put tape on that one contact and not the others.
I've just done it with tweezers. Didn't work though because it turned out the printer in question NEEDED the 5V due to a lack of its own regulator 
1 Like
Yeah... I mention this in the USBControl plugin's README: sometimes it just results in no communication to the printer board.
