not that I'm aware of
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It hasn't been said here but turning of the power to the RPi without a proper shutdown has a non-zero probability of corrupting the RPi SD card. The RPi doesn't consume much power and having it on even when the printer is off can be very useful.
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I tried this and it does not work.
Initially I saw this and it seems to make sense. Then I realize that ADUM4160 also need power supply on the downstream side (printer) but you are not suppose to use the downstream 5V, and Ender 3 indeed does not supply 5V to micro-USB side which makes sense since you cannot connect two 5V together in normal case. Once you removed the isolated DC-DC converter (BTW it is not a transformer) the downstream side is completely powered down and disconnect the printer from RPi.
@coldfire0200: Surely both sides need 5V-Power! And yes, I powered the downside from my 3d-printers 5V-source (normally a cheap 7805-IC or, and on expensiver boards a DC-DC-Buck-converter (from 12V...24V) to +5V. So it's no problem to find out a pin from your printers board powered with his +5V-line and solder a small cable to the USB-plus-Pin, respective the ADUM's +Vbus1 (Pin-1) or Vbus2 (Pin-16) side. Anyhow the two +5V lines have to be completely independent (=isolated) from each-other, so no matter what the original Isolator was(? B0505S datasheet), both sides have to be powered with +5V beeing completely isolated, as well as each pair of USB-Data-lines as the two +5V lines, to get Serial-Connection between RPi and Printer!
It's also possible to add a separate 5V-Supply to the Printers USB-Side (if the USB-Port isn't powered by the printer itself), so adding f.ex. a LM1117-5V Regulator-IC (or a separate 5V Power-Supply) does the job.
And yes: you can connect two lines of 5V together without damaging anything, assuming both sides have nearly the same voltage-levels between 5,00 to 5,1x Volts, but in this case it's safer to separate them, because the printer often has more 5V-consuming-Amperage as the RPi's Power-source can provide (mostly 2-3A) or viceversa... So if one side can't provide them, the 5V-voltage drops down until one of both sides main-IC's /controllers (hardware-)"watchdogs" shut's down (=resets)...
But as @Sembazuru said, this behavior is not here the case but the late "handshake" from Octoprint, trying to connect the waiting Printer. This is normal and no matter to worry about. You have only to wait after Octoprint is ready with its connection to the printer...
@b-morgan: I made a RPI-Hardware "Save-Power-Shutdown" ā you may download it (eagle-files, incl. Excellon-file & Toner-Direct-Print-Out) from my homepage, so corrupting the RPi's SD-card is more unlikely.
I made both hardware-solutions presented here and both are working fine since about mid-2020.
@Andri_Mar: If the Serial-line of your printer-board is dead I would try to desolder and change-out the Serial IC (mostly a CH340C) with 350Ā°C hot-air. So you may save your board - if no other IC is "dead"... and if successful, I would then try to save at least the .hex-file from the board's controller, so you have at least a "hardware"-backup for a hopefully not next time, but sadly not the possibility to modify any lost marlin-files further... Try this (on a command-line in the avrdude-folder):
avrdude -patmega2560 -carduino -P [COM-PORT] -b115200 -U flash:r:"flash.hex":r
where you have to find-out your serial-Port, replacing here the named [COM-PORT], on Linux usually /dev/ttyUSB0 and on a PC usually "COM2" to "COMXX".
Your backup then is the "flash.hex" file.
This tape solution does not work for my Ender 3 Pro. Wish I had known about this issue before spending money on the Pi and it's peripherals.
You know, it would be a lot easier to just cut the 5v wire...
Was just wondering when I had to wire in the USB connecter to the mother board of the Qidi X plus which is very easy to do. The Guy in the youtube video said not to connect the 5V DuPont connecter on the mother board side maybe this was to stop some problems like this happening in the first place. Glad I did not connect it now. my best Daz
worked very well on my Ender 3v2 printer
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electrician here, your good with masking tape, painters tape or even some scotch tape. The only problem is if it will stick once you slide in the usb cord. I wouldn't use duct tape since you could have a possibility the glue from the tape getting all over the inside of the usb jack. electrical tape is the best and only about 99 cents a roll, also good for future projects. you can even find the stuff at the grocery store
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I forgot to fit
a back to back USB plug-socket assembly like this 
which I use routinely for all Pi-Printer connections. The assembly disconnects the +5V rail from whatever the Pi USB is connected to - this was on a CR10SPro mini USB port - there was sufficient power to keep a Raspberry Pi4 alive. Its a bit confusing when you KNOW its shutdown, but the network RJ45 port leds on the Pi are still lit.
Not pretty, I should make cases for them, but they work..
Same thing here:
Since using a webcam with octoprint the message about under voltage is coming up.
Does the cut out 5V work with an Anycubic Mega S too?
Thx in advance
EDIT: it works, but the undervoltage message is still there, IĀ“ll try another power supply and report here again
EDIT2:
After taping the 5V pin and rebooting the complete system (Raspberry Pi with Octoprint) it works fine. IĀ“ll have a look for another power supply, but actually it seems to run without failure messages.
EDIT3: After 6 hours of printing there no message of undervoltage, but then after about a further hour while not printing the message is there again. I donĀ“t know why, but another power supply is definitly needed!
EDIT4: I took another USB-cable and cut out the 5V-pin within the cable itself. Then I took a 5,1V 3A power supply which is now tested. IĀ“ll report again....
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glad to hear that. I'm also running it on an ender 3 v2 with a pi zero w 2 board
I have it set up on my ender 3 pro as well as ender 3 and v2. Are you sure your piece of tape didn't slide off the plate and cause a accidental connection? You can also cut one of the wires in the usb line as well. It really is an awesome set up so don't give up on it yet. But if you do I'd be happy to buy your pi board.
I bought an original Raspberry Pi 4 power supply like this one with 5,1V 3A.
With an adaptor from USB C to micro USB it works very well, no undervoltage message anymore since then.
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What would be the best course of action for someone with a Pi Zero 2 W and an Ender 3 V2? The interface on both is micro-usb. Do we need to forgo the one short micro usb to micro usb otg cable for 2 micro-to-usb A in order to tape the 5v or use a Blough type USB-A power killer device? (Sad if so, it would be so clean to keep that short micro to micro cable in play)
It's a bit different for a Pi Zero 2. It doesn't have a usb hub and afaik the power lines directly connected to the usb power input - that also means the power output isn't limited by the hub controller.
So if you don't have undevoltage issues you don't need to anything.
If you still want to block the 5V, I would recommend the OTG adapter method.
It works well on my Ender 3.
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Just to add to āPrinter models we've so far seen this reported for areā
My Monoprice Maker Select Plus AKA Wanhao Duplicator i3 Plus had this issue and covering the 5V pin fixed it
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Just a note: for my Ender 3 and 3 Pro, I needed to cover the power pin. However for my Ender 2 Pro (the mini Ender) I didn't have to. Perhaps that model only utilizes the data pins on the stock main board.
So, if this tape method works for your printer, is it safe to do it in 2023?