MMU2(S) control board freeze  

RE: MMU2(S) control board freeze

Can you verify that all the cable connectors on the MMU are seated correctly? Also check the connections at the Einsy end as well. There have been reports of intermittent issues if the power or data connections to the MMU are not secure. 

RE: MMU2(S) control board freeze

Posted by: @tom-m11

Hello,

 

I have problems with my MMU2 and am not sure where it comes from. My MMU2 freezes 2 days in a row (print with more than 2200 color changes).

My printer shutdown the nozzle temperature and ask for MMU2 needs user attention.

In the front of my MMU I see only one green led on the right is on from the last used filament. The MMU does not respond to any of the 3 buttons. Only after a long reset on the side of the MMU can I use the MMU again.

Is there a problem with my control board?

 

Some history:

• I have the MMU2 since September 2018
• I had a lot of problems with the MMU2 and it has ended up in the box again
• At the beginning of this year (2020) I took it back out of the box
• Everything has been reprinted in PETG and upgraded to MK3S / MMu2S
• I installed the last firmware for both control boards (MK3S and MMU2S)
• Again I had many problems, but I was able to solve everything (cause was the setup and the buffer)
• After that I was able to print a lot without any problems (50 to 500 color changes per print)
• Then I started with a larger print with more than 2200 color changes
  1. First failed after 40 hours of printing by my 18 month old son (he interrupted the power supply of my RPi4 with octoprint)
  2. The second went wrong after 50 hours with a clogged nozzle
  3. The third attempt was successful for 99.9% (1 layer not good, I think nozzle clogged again) and the MMU2 needed attention several times
     • Finally found the problem (the tip of the filament was between the 2.08 and 2.32 mm out of the extruder)
     • I completely overhauled the extruder and now is the tip smaller than 2.0mm and very nice
  4. I made a 4th attempt with the same gcode and after more than 20 hours it's like my MMU2 is frozen
     • The filament is out of the extruder with a nice small tip (gears from my MK3S), but the MMU2 does nothing
     • I only get a message from the printer that the MMU2 needs attention
     • No light flashes to know what the problem is and no button responds
     • I turned the printer off completely
  5. I started with a 5th attempt, but again the same problem (freezing of the MMU2)
     • After resetting the MMU2 and some forcing, I got the print working again

Anyone have any idea what to do next, replace the control board?

 

I did the same print with my other MK3s and the Palette 2S. Everything went perfectly without problems. Only 2 days longer and almost twice as much filament needed than the MK3S + MMU2S.

 

Thanks for the help

The long print time can overheat the stepper motor drivers. I would attach heatsinks to the driver modules.

RE: MMU2(S) control board freeze

Posted by: @karl-herbert

Posted by: @tom-m11

Hello,

 

I have problems with my MMU2 and am not sure where it comes from. My MMU2 freezes 2 days in a row (print with more than 2200 color changes).

My printer shutdown the nozzle temperature and ask for MMU2 needs user attention.

In the front of my MMU I see only one green led on the right is on from the last used filament. The MMU does not respond to any of the 3 buttons. Only after a long reset on the side of the MMU can I use the MMU again.

Is there a problem with my control board?

 

Some history:

• I have the MMU2 since September 2018
• I had a lot of problems with the MMU2 and it has ended up in the box again
• At the beginning of this year (2020) I took it back out of the box
• Everything has been reprinted in PETG and upgraded to MK3S / MMu2S
• I installed the last firmware for both control boards (MK3S and MMU2S)
• Again I had many problems, but I was able to solve everything (cause was the setup and the buffer)
• After that I was able to print a lot without any problems (50 to 500 color changes per print)
• Then I started with a larger print with more than 2200 color changes
  1. First failed after 40 hours of printing by my 18 month old son (he interrupted the power supply of my RPi4 with octoprint)
  2. The second went wrong after 50 hours with a clogged nozzle
  3. The third attempt was successful for 99.9% (1 layer not good, I think nozzle clogged again) and the MMU2 needed attention several times
     • Finally found the problem (the tip of the filament was between the 2.08 and 2.32 mm out of the extruder)
     • I completely overhauled the extruder and now is the tip smaller than 2.0mm and very nice
  4. I made a 4th attempt with the same gcode and after more than 20 hours it's like my MMU2 is frozen
     • The filament is out of the extruder with a nice small tip (gears from my MK3S), but the MMU2 does nothing
     • I only get a message from the printer that the MMU2 needs attention
     • No light flashes to know what the problem is and no button responds
     • I turned the printer off completely
  5. I started with a 5th attempt, but again the same problem (freezing of the MMU2)
     • After resetting the MMU2 and some forcing, I got the print working again

Anyone have any idea what to do next, replace the control board?

 

I did the same print with my other MK3s and the Palette 2S. Everything went perfectly without problems. Only 2 days longer and almost twice as much filament needed than the MK3S + MMU2S.

 

Thanks for the help

The long print time can overheat the stepper motor drivers. I would attach heatsinks to the driver modules.

I have the same issue. I have 3 MMU2S and one of them has the problems like you described. Is it really because the overheat of the stepper drivers? Can someone confirm that?

My MMU2S also simply dont react after some printing time. It shows only the green light and no button in the front is working if i click on them.

However, i have found an workaround, that the printer can still finish the print.

i unload the filament manually and press the MMU reset button. Then the MMU2S will home again and i can start the print where it ended.

But this is no solution for me.. i really want to fix the issue. If the overheat of the stepper drivers really is the problem, where can i find heatsinks and how can i attach them?

Thank you.

RE: MMU2(S) control board freeze

@danistra

One of my experiences with the MMU2 is that it does not like heat. Outside the enclosure, it works very well. As soon as I operate this in the enclosure at about 35-40 degrees C., the malfunctions accumulate. Once I broke the board while operating it in the enclosure. Since then I have equipped the driver components with heat sinks (the same as on the Einsyboard) and cool additionally with a Noktua fan. There are a lot of things to consider for safe operation. Some good information about it here:

RE: MMU2(S) control board freeze

@karl-herbert

thanks for your reply and the posted videos.

Basically my MMU works fine for me so far and the only problem i have is the issue, that the MMU just stops reacting after some time. I have no idea where it comes from. In the videos i cant find a problem like we descriped or am i missing something? 

I have 3 MMU2S and my first (much older MMU) has no problems like that, only the two other new ones have the problem with the reaction of the MMU. It feels like, that they changed something in the electronics and something went wrong there after a couple of time... Do you still have problems with that MMU frozen thing??

Regards

Daniel

RE: MMU2(S) control board freeze

I replaced the MMU2 motherboard but the problem remained the same. After that I stopped using the MMU2.

I also have a 2nd MK3S in combination with the Palette 2. There I have problems with layer shifts on the X axis.

I swapped the 2 printers, and the printer with layer shifts I replaced a lot of parts (belt, motor, hotend, ...).

Then I tested the MMU2S again and currently works without problems on the switched printer.

RE: MMU2(S) control board freeze

@danistra

What is very important: There should be no dirt or filament debris in the area of the MMU2 and both sensors (MMU2 and extruder) must be precisely adjusted. The holes which the filament passes through should be absolutely clean and free of dirt. I have replaced the 4/2 PTFEs with 4/2.5 PTFEs.

The thing definitely does not like too much heat (mount outside the enclosure).