RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
In the interest of finding a cause or at least a lead, could folks with this issue answer the following questions:
-> What PSU do you have? (silver stock/black stock/other you bought yourself(e.g. meanwell))
-> What MMU firmware version?
-> MMU in stealth or normal mode?
-> What does Support->Voltages report on your printer when this happens? If you have a DMM, also check/report voltages at the MMU board itself.
-> Do you have any non-stock mods to the MMU setup? (different spool holders, buffer changes, different PTFE...)
-> Where are your spools mounted? (above/below/behind printer)
PSU: Silver stock
Firmware: MMU2S v 1.0.6-372 - MK3S v 3.8.0-2684
MMU Mode: both Stealth and Normal
Voltages reported: PWR 23,8V BED 23,8V
MMU Mods: Underslung control panel ( https://www.thingiverse.com/thing:3211711 ), Selector with magnet and opened FINDA canal ( https://www.thingiverse.com/thing:3528314 ), added springs to selector screws
Other mods: replaced the stock extruder PTFE tube with a transparent one, IKEA Lack enclosure with power supply mounted externally, longer cables from the power supply to Einsy board. Raspberry Pi Zero W directly connected to the Einsy board.
Spools buffer is located on top of the enclosure.
I upgraded to the latest firmware some weeks ago and until today I had no issues.
Then today, after finishing a single filament print, the extruder motor pulled the filament out of the extruder, but the MMU didn't unload it, and all red and green leds started blinking.
I tried to reset and switch on/off the printer multiple times, but the behaviour was erratic. Sometimes it started normally, sometimes all MMU motors remained still, only the led were flashing like in the normal sequence, and sometimes it ended with all leds blinking.
I tried to unplug the power cables and replaced them with stock ones, and double checked the connections, but I didn't see any significant improvements.
After various attempts I was able to start a print in single filament mode and it seemed to work normally. But while printing I noticed that the MMU had a reset (I heared the drum banging inside the MMU like in the startup sequence), but this didn't affect the print job. And when the print was finished the MMU didn't unload the filament, like the first time the issue appeared.
I noticed also that when printing, the MMU motors were completely cold. I don't know if it's normal.
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
So been onto support about this, again, and they asked me to check my power wires.
Turns out I had incorrectly installed them, with the curved pins pointing down instead of up. This might've been the root of the issue.
Flipped them the correct way, but still getting the issue so have arranged replacement cables from Prusa and will see if that sorts it out.
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
So been onto support about this, again, and they asked me to check my power wires.
Turns out I had incorrectly installed them, with the curved pins pointing down instead of up. This might've been the root of the issue.
Flipped them the correct way, but still getting the issue so have arranged replacement cables from Prusa and will see if that sorts it out.
Hi Andarne. I also suspect the problem might be related to power, especially the current in the stepper motors. The handbook states that all five leds blinking red and green means that the Trinamic drivers are not able to provide enough power for steppers motors (par 13.4). It says that "A possible cause can be a broken MMU2S power supply wiring, connectors etc".
And @ironjoe13 solved it by lowering the stepper motors current via firmware mod.
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I also had the problem.
Did troubleshoot quite some time...
What I was able to, is to trace the fault also being in relation to temperature...
Printing with Prusa PETG with stock profile in Slicer gave me loads of these disco-events, somewhere around 75% of all the MMU-operations ended in errors. However, when I started with a cold printer, I had 100% success. Problems always started after maybe 10 minutes of printing.
Printing with Prusament PLA and stock profile gave me no errors at all...
My diagnosis went into the direction of thermal-fault, either at the board or the drum's motor. Unfortunately, answer from support (after stating what I have done and how I got to my conclusion) was more or less: "is it plugged in?". Which to me is a complete anti-viagra, never answered to that email...
Reading now that lowering the stepper's current solves the problem, I see two possibilities:
First, I suspect Trinamics on the MMU-board loosing their performance over time, and what we experience is actually a symptom of "old age", that will affect every user with time...
Second, I also noted that with progressing firmware-releases, after one update, the selector acted differently. Instead of consistently driving against the end-stop to detect end-of-travel by detecting a missing step, it would now rattle sometimes for a second to detect the missing step. Again, if the unit is heated from printing PETG, the symptom is more evident, while starting with a cold printer and with PLA it almost behaves like normal, one bang and a lost step is detected. So, could it be that the current was upped in subsequent firmware-updates? To help those battling against load and unload errors due friction in their setup?
I only wish I was able to compile the firmware on my own, so I could analyse and fiddle with the values on my own... 🙁
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I've found the failure of the selector to home can easily come from one of the guide rails being loose and being able to slide back and forth. Fixing it from sliding with a thin shim stops that happening. In my case it's the upper one as the holes seem slightly looser than the lower one.
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
Loose rails could add a springiness when hitting the end-stop, damping the current to some extend. I second that.
However, if the threshold in current is increased to a higher value, or the driver's current-sensor has degraded and measures wrong, the springy rails only exaggerate the symptoms. An increased stepper current actually would increase wear on the rails and drivers...
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I have recurring problems with the MMU2S.
It may work for a period, somtimes quite long.
But when it decides to f**k with mee, it will do all possible sort of things:
-Saying "loading filament 236" and then running away from filament 1 port to a position between 4 and 5.
-Not doing the alignment at all, and staying with the selector motor at present position.
I will try to check the connectors, for bad Connection.
Latest F/W, silver PSU.
Where do I check/change the MMU mode ?
Mk3S+, Mk4 MMU2S never worked properly
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
Where do I check/change the MMU mode ?
Settings -> Mode
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
Hello,
emanuele-i wrote:
Then today, after finishing a single filament print, the extruder motor pulled the filament out of the extruder, but the MMU didn't unload it, and all red and green leds started blinking.
I tried to reset and switch on/off the printer multiple times, but the behaviour was erratic. Sometimes it started normally, sometimes all MMU motors remained still, only the led were flashing like in the normal sequence, and sometimes it ended with all leds blinking.
I have the same issue. Is there any update on this topic?
Did anybody changed the wires to a larger diameter? Maybe the wire gauge is to small for the amount power!?
My configuration:
- MK3S with MMU2s
- latest Firmware
- Octoprint on a Raspberry pi zero
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I reinstalled all the power cables and the data cable and now everything looks fine and the filament change works good. Prusa should improve the connectors! By the way: Why are there 2 x 2 parallel power wires from the Einsy to the MMU?
Its a bit strange that obviously a small change to the power connectors are responsible for a non-working MMU. Actually the problems with my MMU started after I added cooling fins to the stepper drivers on the Einsy-Board. I did not remove any cable and checked all connectors afterwards, but so far it looks like some connectors were moved slightly. Enough to cause trouble with my MMU, since reinstalling solved my problem!
Hopefully this helps other users who are struggling with blinking LEDs, non working stepper motors and other curios behavior of the MMU 🤗.
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I was getting five flashing when it tried to change materials. Ended up my FINDA had gotten moved or something and was always sensing 'filament' when there wasn't any. Recalibrated and now it seems to work. Don't know how the FINDA whacked.
What is stealth mode for the printer and the MMU???
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
The same here. More an more until now where I can´t use it anymore... permanently that error. What a mess!! -.-
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I recommend to use normal mode instead of stealth. Beside of that, most of the errors is a result of wrong sensor placements.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I soldered a regular power cable 1,5 or 2mm³ from MMU board to PSU ... no issues anymore.
Otherwise how do I come from normal to stealth or vice versa?
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
Hi everybody,
I had (have) the same problem (all 5 leds flashing red and green for 3 times) and I might confirm that it is a power problem (even I didnt't believe for a long time). beside the fact, that it helps when filament and ir-sensor work properly ;-).
I checked all my connections, more than once and reinstalled MMU - more than once. Everything was connected correctly, I reconnected everything - more than once. That often resolved the problem for 1 print or 2, but rarely more. It did put some contact spray - with the same effect: ok for 1-2 prints, but than: the same problem occured.
Finally, I change my plug. And it seems helping...
Voltage is stable at 23.6/7 for power, more or less the same for the bed.
Black Power Unit.
Lates firmware, stealth mode for MMU.
It's really a pitty and annoying, but it seems to be a power problem (often combined with sensor or/and filment stringing problems as well as problems with how hard you have to screw MMU and/or the extruder).
Hope this will help some of you.
Yours, Thomas
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
...since my last post I have an update...
As I suspected hair-fracture of either a solder-joint or the pcb itself, I loosened the screws that hold the pcb in place. They're only tightened to the point where they're fully in, but no torque applied.
After all, there's no force supposed up there, that could lift the unit or shift it around...
Interestingly - no more problems...
Whereas before, it would go into error from homing the selector alone (actually the error occurred when the selector was stopped after it moved to the right position and it kept repeating). Now I can work with the MMU as it should be.
It's just sad that such findings will be dismissed straight away by support - experience says, or statistically yaddayadda... I understand that some people are unable to plugin a connector the right way and would even blame Prusa for that. But if support gets presented a 'chain of evidence', they should at least listen...
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
Yesterday I had this problem again. So I unplugged all wiring from MMU2 (power, signal and motors), cleaned the contacts and replugged back, and now it's working again normally.
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
The only way i have gotten around this, thank god for the power fail piece that was built into these printers. but if all the lights start flashing like that, do the following. Unplug the power supply and plug it back in... the print will start where it left off 😉
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
@kyle-a3
I just got finished debugging a second error with the shipped MMU, finally. I no longer have flashing lights and the selector moves freely. At first I had errors and had to replace the idler barrel due to a misaligned shaft. I still had an occasional blockage with lights when the selector went back and forth. The brass farrel slipped out and I'd no idea the cause. Finally last night I printed a selector mod with the magnet to clear a problem with the filament not going past the festo. As I disassembled the unit I noticed the serious drag when moving the selector across the rods.
Once again an alignment problem due to a minor warping of the selector body, probably since day one. The NEMA motors are strong and even with all of that drag mostly were able to move the selector across the rails. That said, I got out the old brogan maintenance instincts and drilled the holes where the rods didn't line up exactly to the holes. I only took a little material out of the holes that I felt would clear up the problem, luckily I got it right. The selector doesn't have any movement save the horizontal. I put it together and did a five material print without any errors.
I suspect that the unit was out of tolerance since day one. No more lights flashing just lock and load, the way things should've been since the begining.
Stay safe,
Phil
Stay safe and healthy, Phil
RE: MMU2S keeps resetting/Red & Green LED's flashing at once.
I updated the firmware and I am at 100% failure rate now with this freaking thing. Looks like I need to start the painful process of figuring out what issue could be causing this.