I found serious design error in MMU2 electronics hardware

I found serious design error in MMU2 electronics hardware  

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Please remember that Prusa is still not a massive multi-national company with 100s of software and hardware developers.  They now have to support MK2.5s, MK3s, MINIs, SL1s/CW1s, MMU2s, PrusaSlicer, and the R&D of future products.  The MK3S and MMU2S was released in Feb 2019 and the MK3S+ in November 2020. Bare in mind that during that time and up to now the whole Pandemic has been going on!  They might have planned for a MMU2s+ for all we know but it had to be delayed. (No insider knowledge, sorry). Or maybe they've decided to skip the MMU2S+ and go for a MMU3 with major redesigns?

There have been some hardware (3D printed) updates since 2018 so they have still been working on things.

Considering how many companies have had to close for the last year and a half we should probably be thankful Prusa has managed to stay running during it all.

Let's look on the positive here, someone has found a fault and a fix and had the decency to share it with everyone, including the technical details with Prusa.  So give the USB technique a try and see if it solves some of your problems with the MMU2(s).

Posted : 01/04/2021 3:10 am
Estimable Member


Hi, if you look very closely at my post you‘ll see that I responded to 3delight‘s post ( „Posted by: @3delight“) and not heine-mau‘s (kudos to him for being able and qualified to find such a design flaw and kind enough to do so and post it). I too have an MMU2, and it‘s working quite well and I would be delighted if development and support of that thing would continue and prosper - I just have serious doubts that it is.

So I‘d like to know and hereby clarify my question: does anyone at prusa  care?? Do they still work on developing and improving the MMU2?

If at first you don't succeed, skydiving is not for you....
Posted : 01/04/2021 8:36 am
Same Old Shane

Hello all;

The process for submitting a issue to github was provided and followed. Those tickets go directly to the developers and are assigned. 

If development on the MMU project was terminated, it would be announced (the same where a product reaches its service life and is phased out in production), and the moderator would have instead said that the project was discontinued, but that is not the case. 

The Pandemic really has taken a toll in many different areas. This is not an excuse but unfortunately a  fact. If you look at the companies track record we release new products on a yearly basis, and with those innovations, if there was a feature that could be carried over to a previous model it was done so. That is where the .5 or S iterations come from. 

The MMU project is still active and is always being worked on. For this particular case, as said before, it has been submitted and will be reviewed. If there is a benefit and can be worked into a future version of the MMU and also be carried over to older units, it will be done so as well. As far as a time line on this. Unfortunately, that I can not say. While there are signs of some areas of the world improving from the pandemic, other places are not. Even more recent events, (for example) the blockage at the Suez canal, while not directly affect one company, it could affect a different company that supplies goods (I am saying that ONLY as an example of things that can affect development for any company). 

We love innovating and continue to develop new products and also improve on existing ones. As much as people want us to release new types of machines, we want to get them out there and we are working on that while navigating a lot of challenges that pop up at random times that are well beyond our control. In time things will return to normal and we will catch up and be back on schedule of things. In the mean time we do need to be patient. 

Thank you. 

Shane (AKA FromPrusa)...
Posted : 02/04/2021 10:05 am
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