MMU2S red and green lights blinking (2024)

(@blastermak)

New Member

MMU2S red and green lights blinking

Hi all,

I've had my MMU2S for a while now and I've been getting on and off results with it. 90% of the time when I start a print and the MMU boots up and homes it will go and blink all five red and green leds. The corresponding explanation is that the trinamic motors can't get enough power to function properly. This repeats for a couple times but eventually hangs and stays blinking. If I'm lucky the print will start but so far I've only done single colour prints because I'm afraid it will hang mid-print

I have double checked and every connection is how it should be and I've got no other components hooked up to the power supply or EINSY board. I'm using all stock parts except the ptfe adaptar for the MMU2S unit and a mod to mount the MMU2S control board to the underside

(@vintagepc)

Member

RE: MMU2S red and green lights blinking

Try loosening your MMU idler screws slightly. I find the default has a death grip on the filament and isn't necessary for me.

(@blastermak)

New Member

Topic starter answered:

RE: MMU2S red and green lights blinking

That doesn't seem to fix it, got the same result of the mmu initializing, failing and trying again for a couple before being stuck with the flashing lights.

Any insightfull debug tools I can use?

(@karl-herbert)

Illustrious Member

RE: MMU2S red and green lights blinking

Posted by: @account

Hi all,

I've had my MMU2S for a while now and I've been getting on and off results with it. 90% of the time when I start a print and the MMU boots up and homes it will go and blink all five red and green leds. The corresponding explanation is that the trinamic motors can't get enough power to function properly. This repeats for a couple times but eventually hangs and stays blinking. If I'm lucky the print will start but so far I've only done single colour prints because I'm afraid it will hang mid-print

I have double checked and every connection is how it should be and I've got no other components hooked up to the power supply or EINSY board. I'm using all stock parts except the ptfe adaptar for the MMU2S unit and a mod to mount the MMU2S control board to the underside

It would also be possible that filament residues block the selector or the sensor or the drivers on the board are overheated if printing in an enclosure.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

(@lichtjaeger)

Noble Member

RE: MMU2S red and green lights blinking

(@blastermak)

New Member

Topic starter answered:

RE: MMU2S red and green lights blinking

I've been doing some tinkering and after I've put it back together every load and unload happened succesfully. The only noteworthy thing I've done is tightening the screws on the idler shaft some more.

Unfortunately after running a succesfull print this evening during the unload it got stuck on the red/green blinking lights. Might this have something to do because I'm printing in an enclosure?

(@davbow)

New Member

RE: MMU2S red and green lights blinking

I think if the lights are blinking red and green then whatever problem the MMU thinks it had has been fixed. Press the right button to continue.

(@kylian)

Active Member

Enclosure

I have same problems and my printer is in an enclosure. I'm seriously thinking the problem is with the heat inside the enclosure. Im looking for a solution to refresh the controller.

(@andarne)

Eminent Member

Try adding a USB cable to the MMU2

Try running a USB cable from the MMU2 unit to a PC or powerbank/mains plug. I've been doing this, and ran over 7k colour changes without issue since doing it. Seems like the MMU2 can't draw enough power, so by adding the powered cable it gives just enough to get it working again.

(@karl-herbert)

Illustrious Member

Voltage drops...

Voltage drops can actually cause malfunctions of this kind. For this reason I would also try to supply the MMU2 with an extra 5V source.

wbr,

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

(@cvk)

Active Member

USB and voltage drops.

I'm having this problem, 5 lights flashing at unload/99% done, with my MK2.5S MMU2s. Would the 5v go to the firmware usb port directly? Do you think running a usb from a RasPi running octoprint to the MMU2S would provide needed voltage? Also, how can I check the voltage?

Posted by: @andarne

Try running a USB cable from the MMU2 unit to a PC or powerbank/mains plug. I've been doing this, and ran over 7k colour changes without issue since doing it. Seems like the MMU2 can't draw enough power, so by adding the powered cable it gives just enough to get it working again.

(@kylian)

Active Member

It works for the moment thanks to your suggestion.

Thank you for your replay. Simpli pluging a USB cable from de MMU2s to a simple phone charger did the job. For the moment the error did not occur again.

(@andarne)

Eminent Member

RE: MMU2S red and green lights blinking

Yes, to the Micro-USB port on the MMU2S. I'm currently running a cable from my RaspberryPi with OctoPrint on it, and zero problems.

Posted by: @cvk

I'm having this problem, 5 lights flashing at unload/99% done, with my MK2.5S MMU2s. Would the 5v go to the firmware usb port directly? Do you think running a usb from a RasPi running octoprint to the MMU2S would provide needed voltage? Also, how can I check the voltage?

Posted by: @andarne

Try running a USB cable from the MMU2 unit to a PC or powerbank/mains plug. I've been doing this, and ran over 7k colour changes without issue since doing it. Seems like the MMU2 can't draw enough power, so by adding the powered cable it gives just enough to get it working again.

(@kylian)

Active Member

RE: MMU2S red and green lights blinking

¨Running a USB cable worked" worked for a while, but the problem happened again.

I read a lot of documentation. Of course I found Prusa advice on this page:

https://help.prusa3d.com/en/article/mmu2s-leds-meaning_2187

I tried Prusa support advices by disconnecting all cables from the MMU2s, cleaning them and reconnecting them. I have also updated the firmware of my MK3s printer and MMU2s to the latest version (3.10.0 - 1.0.6).

I found an interesting discussion on the forum that reports the same issue from several users:

https://forum.prusa3d.com/forum/original-prusa-i3-mmu2s-mmu2-hardware-firmware-and-software-help/mmu2s-keeps-resetting-red-green-leds-flashing-at-once/

The behavior is erratic. No fix seems to work. I suspected a faulty MMU2s board. Finaly I contacted Prusa support and this was the answer:

"In addition to what you've tried already, could you also perform a factory reset of the MM control board itself (not the printer), and let me know if it will help."

https://help.prusa3d.com/en/guide/service-menu-factory-reset_86232

I did it and "oh miracle" the problem was solved.

(@karl-herbert)

Illustrious Member

RE:

A master reset often works miracles. I hope the MMU2 will run without problems for a long time 👍

happy printing!

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

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