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MMU2S Motors unresponsive after long print  

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jgillick
(@jgillick)
Active Member
MMU2S Motors unresponsive after long print

My MMU2S was working perfectly for months, but suddenly it started becoming unresponsive after prints longer than 30 minutes.

After a print, the motors in the MMU2 are completely unresponsive and do not unload the filament. Pressing the buttons don't do anything. If I manually pull the filament all the way out and press the reset button on the MMU2 unit, the motors still don't work. Even stranger, if I press the right/left buttons, the LEDs indicate that the filament selector has moved (i.e. from 1 to 2), but the actual selector didn't budge. The only solution is to completely power down and power back up. Then everything works fine.

I'm on the latest firmware for both the MK3S and the MMU2S.

Posted : 26/02/2020 4:49 pm
vintagepc
(@vintagepc)
RE: MMU2S Motors unresponsive after long print

Does the board feel hot? the TMC drivers might be shutting down due to overtemperature.

Posted : 26/02/2020 5:09 pm
Mirar
(@mirar)
Estimable Member
RE: MMU2S Motors unresponsive after long print

I have the __exact__ same issue since a few months.

 

It seems to happen randomly, even with the printer in idle. Is there a thermal fuse or something on the board?

The board is hard to access or thermally image.

 

Is there a known solution?

Posted : 02/03/2020 3:20 pm
jgillick
(@jgillick)
Active Member
Topic starter answered:
RE: MMU2S Motors unresponsive after long print

It turned out that the MMU2 motherboard needed to be replaced. Prusa Support was amazing and helped me get this sorted. Everything is back up and humming again.

Posted : 24/03/2020 6:43 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: MMU2S Motors unresponsive after long print

@jeremy-g10

After a long multicolor print in an enclosure, my MMU2 board broke due to overheating. After replacing the board with the latest version and now actively cooling (the drivers) there are no more problems and the MMU2 is now running reliably.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 24/03/2020 9:48 pm
Mirar
(@mirar)
Estimable Member
RE: MMU2S Motors unresponsive after long print

Oh, that's good. I will see if I can get a new board too.

Posted : 24/03/2020 9:54 pm
Mirar
(@mirar)
Estimable Member
RE: MMU2S Motors unresponsive after long print

I got a new board sent and it solved the issue for me as well. Thanks Prusa!

Posted : 08/04/2020 9:45 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: MMU2S Motors unresponsive after long print

@mirar

Thanks for the feedback!

Happy printing!

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 08/04/2020 11:53 am
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