MMU3/MK4 wouldn't load all the way to extruder gear, now none of the motors are working
Things went from bad to worse. At first, it seemed to be working - it could load filaments to the FINDA, cut the filament, etc. However, it could not load filament all the way to the extruder gears. It would stop just a hair short of the nextruder gear being able to grab it, so it wouldn't load all the way to the nozzle. It could unload the filament just fine.
I tried adjusting the idler tension, but while going through that process, I was trying the Loading Test from the Calibration menu, when it jammed and I had to reset the printer. After that, none of the motors will move. The lights blink on startup but it doesn't go through the homing.
I suspected the jam might have popped a fuse, but I probed what I assume are the fuses (the green components on the lower right of the board where the Buddy interface plugs in), and one of them reads 23.9V on both sides and the other reads 5V on both sides. I suppose it could have damaged the motor drivers themselves but I don't know how that could have affected all 3 motors.
Are there any low-level troubleshooting steps I could do?
RE: MMU3/MK4 wouldn't load all the way to extruder gear, now none of the motors are working
Have you reset the idler tension again? too tight will stop it rotating
iirc the idler drum is the first stage of MMU3 startup.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: MMU3/MK4 wouldn't load all the way to extruder gear, now none of the motors are working
I've loosened it all the way to pull the filaments out, and I can freely rotate the idler when it is off.
RE:
Here's what the LEDs do on startup:
I also probed the capacitors right above the motor driver chips and all 3 are getting 23-24V. All of the pins going to all motors are stuck at 24V and never go low (at least as far as I can tell with a multimeter, I don't have an oscilloscope)
RE: MMU3/MK4 wouldn't load all the way to extruder gear, now none of the motors are working
Have you spoken to Prusa Chat.
Might be worth pointing to this post
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: MMU3/MK4 wouldn't load all the way to extruder gear, now none of the motors are working
Ok, I figured out what it's trying to do by reading the startup sequence in the firmware. Turns out that I had a piece of filament stuck in the FINDA, so it didn't move any of the motors. I pulled it out and it's back to the original problem - it loads just short of the Nextruder gear and won't actually load.
RE: MMU3/MK4 wouldn't load all the way to extruder gear, now none of the motors are working
Can you try a shorter PTFE Tube?
Do you have a spare?
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE:
I was having a lot of problems with filament only reach halfway to the extruder or if it reached the extruder it wasn’t retracting all the way back through the selector.
The fix for me seems to be realigning the trapezoid nut on the selector. Looten the two screws on the trapezoid nut also loosened the motor nuts and then retightened the motor nuts in order (diagonals first then third corner …. Not too tight on the corner nut) then moved the selector back and forward over the full range under power then held it firmly to the left hand side (position1) whilst retightening the trapezoid nuts. Now seems to work flawlessly. 🤞