MK4S set with MMU3 does not turn on again "MMU overcurrent"
MK4S sets working with MMU3 have a factory defect.
After turning them off and back on, the message "MMU overcurrent" appears.
To make it work again, you need to turn it off and wait—sometimes for a few minutes, sometimes an entire day.
This happens with all seven of my sets. However, my MK4 with MMU3 does not have this issue.
I have already replaced the xBuddy, disconnected cables, and downgraded the firmware to 6.1.4.
None of this helps.
These devices have a defect—they don't work as they should. This has been going on for months.
The question is: when will Prusa create a repair kit to resolve this issue?
RE: MK4S set with MMU3 does not turn on again "MMU overcurrent"
Yup... seems to be a known issue. Happened with my MK4 with the MMU3. I did the upgrade and still happens. Take a look at this comment from a Prusa guy on github. Hopefully they will have a fix soon
https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/3947#issuecomment-2549012311
RE: MK4S set with MMU3 does not turn on again "MMU overcurrent"
Hi, the overcurrent message means the MMU is having to work harder than normal.
(1) - Make sure the PTFE tubing does not have any sharp bends and the filament spools and buffer wheels are turning freely.
(2) - The idler tension should be reduced as much as possible without slipping.
Best wishes and Merry Christmas!
RE: MK4S set with MMU3 does not turn on again "MMU overcurrent"
I see there is some history…. Looks like a lot of ideas being thrown around, but no concrete fixes. I have a few (40+) years of experience working with electronic controllers. This looks to me very much like a grounding issue. Has anyone tried bonding the MMU board to the xBuddy? By that I mean, run a green/yellow wire from the PE terminal on xBuddy to one of the grounded mounting screws on the MMU, similarly to the way the PSU and xLCD units are wired to PE. I guess I should suggest this on GitHub, but I’m not yet set up to comment there. Hope this gets resolved soon as I have a CyberMonday MK4S/MMU3 on the way!
RE: MK4S set with MMU3 does not turn on again "MMU overcurrent"
The fact that they are still selling faulty printers with an unresolved issue that makes them unusable, I consider a SCAM.
RE: MK4S set with MMU3 does not turn on again "MMU overcurrent"
I also had this issue and the only thing that fixed it was to solder a 1 ohm resistor inline each (2 off) the red wires on the cable to the mmu. I still occasionally get an overcurrent error if i press reset but switching it on and off clears this.