MMU3 over current boot up alarm after resetting MK3.5
I upgraded my MK3S+ MMU3 to a MK3.5 MMU3 last week and it had been working great for 4 days until today something weird happened. I had to cancel a print and start another before the filament loaded. After cancelling it wanted to heat up to unload a non-existent filament so I hit the reset button to reboot.
On reboot I got the MMU over current alarm. I tried rebooting 4 times and got it everytime so I powered down the printer and went to the forums for a search. I found the article about MMU overcurrent and the fact that some xbuddy boards appear to be faulty.
I went back to my printer 10 minutes later and it booted up. I've used it for a whole bunch of multicolour prints since but am worried to ever hit reset.
I contacted support and all they suggested was to reload the firmware and not to worry that if it happens again they will work through it with me and solve it.
Anyone else had this happen or something similar?
RE: MMU3 over current boot up alarm after resetting MK3.5
Happened again, but this time the printer crashed on the first bed line of setting up a new steel sheet when I turned the knob. Restart had MMU error. Same wait time required and it reboots ok.
RE: MMU3 over current boot up alarm after resetting MK3.5
Found this solution on Reddit. User tbachtell states:
I have an MK4 and a Mk3.5, both with MMU3. I use Octoprint on both. I was getting frequent over current errors and it was driving me crazy. I finally tried removing the USB running from the RPi to the xBuddy board and never had another over current error. I pull out the USB connection at the RPi when I turn the printers on. Then I plug it in and everything works perfectly. I reported this to Prusa.
I also have a rpi running OctoPrint attached! Unplugging the usb cable solves the MMU overcurrent error. I will report it to Prusa as well if the proble doesn't reoccur for a week.
RE: MMU3 over current boot up alarm after resetting MK3.5
This seems to be a known issue, it is discussed over in the Buddy Board software git. https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/3947
I get this error every time if I have Octoprint / USB plugged in, and intermittently (reliably if hot) if not. Prusa has not been willing to support / warranty this and I am unhappy with the situation.
RE: MMU3 over current boot up alarm after resetting MK3.5
I got the same thing. I tried 3 different firmwares. I had just upgraded my MK3 to MK3.5, everything worked fine. Later when I had my printer set up with Octoprint I got Overcurrent MMU. I remembered that some marlin software/motherboards have sometimes problem with USB power. I simply put a tape strip over 5V pin in the USB cable. There is an article about this at Octoprint search for "Put tape on the 5V pin - Why and how"
RE: MMU3 over current boot up alarm after resetting MK3.5
Here is the link
https://community.octoprint.org/t/put-tape-on-the-5v-pin-why-and-how/13574