I found serious design error in MMU2 electronics hardware  

RE:

I believe this is totally Prusa's decision.,, Historically .......

when I ordered an MMU1 upgrade, Prusa decided to end of life the MMU1 and offered to upgrade me to MMU2 instead, at the same cost. (This seems very responsible of the company)
at the time I Only had the Mk2 printer. 

the MMU2 upgrade came with power wires for the Mk2 printer (needed Mk2.5 upgrade to work) and the mk3 printer  as well (mk2/Mk2.5 had Rambo controller, Mk3 had Einsy controller)
I bought a Mk3 printer about this time
I have been using the MMU2 on the Mk3 ever since it arrived. 
Prusa had issues with the Mk3 Filament sensor, which affected the MMU2, so Prusa upgraded us to Mk3S and MMU2S, This made the MMU2S more reliable. (Again, this was done FOC and seemed very responsible of the company) I changed the PTFE Tubes to 4x2.5mm PTFE and have been using the MMU2S since then. 

The Mk4 has yet a different controller, so I suspect that the power and data wires will be different for the MMU on the MK4 printer. 

The Mk4 printer was not available during Beta testing for the MMU3, so all of the beta testing was completed on Mk3S's, Mk3S+'s and I believe  Mk2.5S's

to the best of my knowledge the MMU3 works better than the MMU2, on the MK3S, Mk3S+ and Mk2.5S

I Suspect that Prusa will offer an Upgrade path for theMMU2S to MMU3 for MK3S, Mk3S+ and Mk2.5S and a different MMU3  package for use on the Mk4... 
But as I stated at the beginning, this is up to Prusa... I Expect that they will want to support the existing MMU2S customers. 

Regards Joan 

RE:

When i had spoken to them (before the MMU3 was released) i asked in detail about the MMU2, they said the Mk4 will get a new MMU3, however this will not fix the Mk3s, it might be they have changed this with 2 versions of the MMU3.... this was as soon as the Mk4 was officially released.

Posted by: @bryn51

I wonder why it is then,  that prusa say there are two slightly different versions of MMU3, one fir Mk3S+ and the other for MK4, the difference being connection to the extruder which are slightly different for each printer. 

RE: I found serious design error in MMU2 electronics hardware

Suspect that Prusa will offer an Upgrade path for theMMU2S to MMU3 for MK3S, Mk3S+ and Mk2.5S and a different MMU3  package for use on the Mk4... 
But as I stated at the beginning, this is up to Prusa... I Expect that they will want to support the existing MMU2S customers.

Yes, Prusa have already said as much. the upgrades are not free this time but at least they are available. Those upgrades are said to be available for sale during june. The only thing unclear is when the mk4 version of mmu3 (with modification to suit nextruder connexion) will bd made available. 

In my case the schedule is inconvenient, I have mk4 kit coming in June I think. I have Mk3S+ and MMU2S. I plan to uograde mk3S+ to mk4 and mmu2S to mmu3, and maybe purchase another whole mmu3 for the mk4. looks likd it will be a couple of montgs until I have a uniform set of printers.

RE: I found serious design error in MMU2 electronics hardware

I suspect the difference between MMU3 for the MK4, and MMK3 for the Mk3s would be the power and data wiring. 
the Mk4 uses a new controller which probably has new connectors or revised pinout, a little like the differences between Mini Rambo and Einsy controller boards

regards Joan

RE: I found serious design error in MMU2 electronics hardware

the main known difference will be arrangement of connecting to the extruder (filament feed) simply because the two extruders are different. the wiring arrangement might be different but Prusa clearly state that the “two way communication” improvement for better error handling / user communication is a mainstream item. Of course it might be implemented differently on the two printers, using different wiring but its speculation. The mmu2 has always had a spare connector on the board, which is I2C i believe, capable of both-way half duplex polled style communication. Best to wait and see to find out, rather than speculate. 

RE: I found serious design error in MMU2 electronics hardware

This might be a somewhat old thread, but I've just gotten my MMU2 back onto the printer and it's giving me power issues left and right. The MMU3 is just promised, and it would be a costly upgrade.

Does anyone here know what even goes on with the prusa mmu2 code? There're basically no comments and the naming is quite confusing for someone like me who's been doing python for a lot longer. Chances are that you could run the code on a skr board with a little modification, they're generally well designed - I have one operating for 2.5 years almost nonstop inside a fanless enclosure, still performs just like new. 

Think best place to start would be swapping the pins over, if someone would like to look into that it is probably the best solution aside from reverse engineering all the communications

RE:

The upgrade kit for MMU2 to MMU3 is already published and it’s $US 89 plus freight.  Not expensive, although I believe its necessary to print your own plastic parts.

Yes  the firmware looks like a spaghetti nightmare, but having looked at it I formed the view  it was going to take too much time to refactor it into proper C++ object oriented form and then decide what changes are needed, then test it. Someone already tried that, but the nett result is code that has no future. For example it would not include support for Mk4 and two way comms. 

Then you mention replacing the mcu board with something else. seems like the cost of all this would go close to prusa’s own upgrade, but not include any of the improved hardware.

The Mmu 3 and upgrade options are due in july, only a few days away. Mmu 2 has already been taken out of Prusa sales catalog. My understanding is that Prusa are now thoroughly testing the MMU3 with 3rd party testers involved, to be followed by production line set up. So it will not be very long now.

RE: Yet Another Hijacked Thread (YAHT)

..

RE: I found serious design error in MMU2 electronics hardware

The MMU3 needs at least the mk3.5 upgrade as well for about £250. That makes the overall upgrade to mmu3 just over £300. The skr is about £30 which is about the same as an arduino and grbl shield with drivers. 

lets hope the MMU3 electronics will be properly fixed. They do mention that there would be more informative troubleshooting messages because of 2 way comms and that they redesigned the plastic parts for reliability. However they didn’t mention anything about the electronic board so I have my doubts in whether they’ll fix the 5v issues.

If it doesn’t work out in the end it doesn’t seem that hard to switch over to skr boards. I’ve had a look at the mmu2 comms code and seems simple enough. IMO if the worst case scenario was to happen with mmu3 I would probably rewrite the whole fw and keep the comms the same, so that the prusa firmware won’t know the difference. I’ve had rock solid performance from the skr e3 boards (actually outlasted the prusa mk3 rambo when the Rambo just died on me a few weeks ago).

The firmware itself is plainly over complicated, but another possibility is to use the skr pico instead and program it in python, where I could probably get it somewhat working within a couple weekends. You did mention testing though, but one would expect the mmu2 to be tested in such a similar way given their claims. 3rd party testing doesn’t mean much for long term reliability of a single mmu board. 

RE: I found serious design error in MMU2 electronics hardware

The MMU3 Upgrade has been announced, lets sit back, relax, and see what happens. 
There is little to be achieved by continuing this thread, 
Thanks for all of your posts. 

regards Joan

RE: I found serious design error in MMU2 electronics hardware

Well lets review this statement "There is little to be achieved by continuing this thread, ", so this assumed all those that have "bad" MMU2s will be receiving a FREE MMU3, is this the case? if so, i agree all those that have a PAID MMU2s that doesnt work no longer need to worry on how to FIX the PAID not fully working MMU2s, if however we are not getting a FREE MMU3 then this thread needs to continue to get the MMU2s purchased to work.

I have an MMU2s that has this issue, i for one will very enjoy my MMU3 i get for free to get my MMU2s working (for which my MMU3 better work on my current MK3s printer).

RE: I found serious design error in MMU2 electronics hardware

The fact is that the MMU2 works perfectly when the 5V upgrade is installed. I have many thousands of filament changes and zero issues on 3 printers with MMU2's since doing the 5v upgrade. This is an actual repair and corrects the actual problem, not a symptomatic fix that will need to be done again in the future.

The MMU3 is still vaporware. 

I have 3 MK3S+'s with MMU2's and they are workhorses. I have a MK4 that is amazing, but would be much better if the MMU3 was a real thing, and if additional heater blocks complete with nozzle adaptor, heater can, and thermistor were available.

RE: I found serious design error in MMU2 electronics hardware

I can totally confirm this. This problem was constantly bugging me up until I installed the 5V upgrade. Ever since the issue is 100% gone and al it cost me was 6€ and some soldering

RE: I found serious design error in MMU2 electronics hardware

Has someone done a nice how-to already for this upgrade? (beside of all the nice posts here in this thread).

RE: I found serious design error in MMU2 electronics hardware

.. not to my knowledge and a nice writeup would probably me a good idea

RE: I found serious design error in MMU2 electronics hardware

I don't know about a detailed how-to, but its not difficult at all.

You literally want to take 24v from the PSU, send that to a BUC converter that will produce 5.2V and then send that 5.2V to the 5V input pin on the MMU2 (blue wire on the power connector from the Einsy board.

Note: you will want to cut that blue wire so you dont back feed 5.2V into the Einsy board.

Its that simple.

I did it with 3 and they are perfect now.

RE: I found serious design error in MMU2 electronics hardware

yep, just a watch out: some of the BUC converters have a screw to adjust the output voltage. You want to adjust it BEFORE installation. Another user accidentally fried his board...

RE: I found serious design error in MMU2 electronics hardware

Yep, make sure you have 5.2V coming out of the BUC _BEFORE_ you connect it to the MMU2 board. _BEFORE_

RE: I found serious design error in MMU2 electronics hardware

"There is little to be achieved by continuing this thread"

The point of this thread is to help others identify, pinpoint and reliably solve the problem, or rather problems. I also hope it conveys some of our needs over to Prusa.

I'd hope Prusa finds a way to fulfill the disappointed mmu2 customers, either by a free mmu3 upgrade, a properly designed board not at the bottom limit of the tmc driver logic voltages or just a plain old refund if they can't get anything working. Not everyone is willing or comfortable to poke a soldering iron at the mmu board.

Well that's my opinion, but I'm going to try out the 5.2v mod after I'm done printing my voron parts, for which I will install a much more reliable multi material system. Hopefully I end up with two multi material printers by the end of this year... and not have any fried mmu2 boards from my terrible soldering.

RE: I found serious design error in MMU2 electronics hardware

Joan, this has been one of the better threads, and will be apropos for many years to come. 

The MK3's and the MMU2's should be around and in use for many years, why not encourage ALL assistance in these matters?

The fact is that many (most?) users cannot afford to upgrade with every new version, and quite frankly its they should not need to.