FINDA probe stuck at 1  

RE: FINDA probe stuck at 1

Answer from customer support:

There have been a few similar cases lately where FINDA caused a problem with functionality of MMU2.

FINDA triggers 1 and it can’t be undone. The problem is probably within the FW - Development department is already working on this issue.

Solution to this issue (for now) - pull the FINDA out of a selector and let the filament load. When it’s in the middle of bowden, it stops. Now MMU is still blinking slowly red. Put the FINDA back to the selector and let the filament go back to MMU unit. MMU unit is blinking red and green, confirm the process with right button.

No need to say that I am not very satisfied 😐 

RE: FINDA probe stuck at 1

one reason many of us switched to a updated selector with a internal magnet to pull the ball down

RE: FINDA probe stuck at 1

Hi David,

do you have a link to that new design?

I just tried the "temporary fix" from customer support. It doesn't work at all.

Cheers

Luca

RE: FINDA probe stuck at 1

@luca-vicini

There are many selectors on thingiverse. Here is one https://www.thingiverse.com/thing:3528314

RE: FINDA probe stuck at 1

https://www.thingiverse.com/thing:3688458    uses a spare prusa magnet instead of a round one

RE: FINDA probe stuck at 1

Hello,

thanks for the help. I will try to print the new part. I believe the sigle material mode still works ok with MMU.

I doubt that it will solve my problem. Once the probe get stuck at 1 there is no way change the status. I even extracted the probe out of the unit to check this.

I am pretty convinced it’s a software or a hardware problem (electronics) not a mechanical issue.

cheers

Luca

RE: FINDA probe stuck at 1

Hi Luca,

I was one of the first to raise this issue to PRUSA months ago. I spent hours with them and we came to the fact that is a Firmware bug.  From several trial, is not really clear if it is a MMU2 FW bug or MK3S FW bug. For sure it affects the communication protocol between MMu2 and MK3S after and error situation in the mid of a print.

I saw in that situation, the MK3S FW is on hold, because it does not want to loose the current print, but since Marlin FW is not really multitask, the MK3S has really a cumbersome way to hold on the current print, writing a message on the display, checking the button pressure on the MMU2, and getting result status from MMU2. So trying to do all this, in a dummy multitask, it messes up something, probably interrupt lines or port data RW, and then it is not any more able to read the FINDA status.

We tried also to replace the FINDA with another, and get the same results.
I looked at the MMU2 FW and I think the issue is around the arduino instruction: PinMode(xFINDAport, INPUT) that is given only at the MMU2 initialization. Something causes a change or a reset in default WRITE mode during the usage, and then is not possible to read any more the FINDA status, since nothing in the FW set it it back in read mode, anywhere than during the INIT.

Regards

RE: FINDA probe stuck at 1

MMU FINDA got stuck at 1 trying to start a print. I was having trouble getting filament to load to nozzle so I was watching sensor status during load and it was stuck at 1. Pulled the FINDA and made sure it was clear. Still stuck. I turned off and on the printer and it cleared. I'm finding a strange problem that relates to what order the MMU2S is switching positions. Using 1 and 2 only, it works great. Using 2 and 4 it will not even load a filament to nozzle at all. This might not be related to the FINDA so I'll post it in general topic.

RE: FINDA probe stuck at 1

I was doing a 4-hour print (single mode) and around 3 hours, it started "air printing" and finally indicated the the print had completed.  In trying to figure out what had happened I saw the FINDA was at 1.  Removing the FINDA didn't clear it.  Doing a reset from the front panel of the MK3S cleared it and it's now working normally, so far.  It was not necessary to power down.  I didn't try a MMU2S reset before I did this.

Firmware:  3.8.0-2684

MMU2: 1.0.6-372

RE: FINDA probe stuck at 1

I just started seeing the exact problem the OP described.  I've not seen this before today.  I can't get it to work in either single regular MMU mode.  After restarting the printer you can look at the FINDA output (Support/Sensors) and it works fine, but after attempting a print and failing the FINDA is stuck at 1.  So far only restarting the printer temporarily fixes it.  

I'm running the most up to date firmware on my Mk3s and MMU2s:  3.8.1 and 1.0.6 respectively.

Thus my MMU is now deadlined.  Awesome.   I really hope Prusa is working on a firmware fix, but seeing as this has been around for a few months I'm worried. 

I've been searching, but have not seen a fix.  Anyone know of one?  For now I can still print if I don't use the MMU.

RE: FINDA probe stuck at 1

I encountered this too today for the first time. I'm running the most up to date firmware on my Mk3s and MMU2s: 3.8.1 and 1.0.6 respectively. Reset of the mmu2 did not work. I had to reset the mk3s and in the process lost the progress of the print. Prusa, please update the firmware.

RE: FINDA probe stuck at 1

walbert, I had so much trouble with the MMU2S that I unplugged all the cables from the MMU which causes the printer to work like it has no MMU. This is the quick way to get rid of the MMU and bypass all software that runs with the MMU connected. I use the change filament feature to change colors but that's limited if you're doing multi colors in each layer. I find that the printer works so much better and more reliable in original configuration before MMU was added. I can easily add the MMU back by plugging the cables back in the MMU. Rather than feeding filament through MMU with it disconnected, I remove the PTFE tube from the MMU and load the filament directly into that tube. The tube is just drapped over the top of the printer for now but I might remove the MMU from the frame, let it lay on the side, and put the original spool holder back on. I find that the change filament feature works great for changing colors, once you master it, and it saves a lot of filament over running multi color with the MMU because there's no purge block for the color change. Also the prints are much faster because there's no purge block at every layer. I just design my print so I know at what layer height I need to do a color change, or just use visual clues during the print. The down side is you have to baby sit the printer if you want to catch the color change at the appropriate time. I had the FINDA problem and somehow got it to start working good, but my problems with the MMU were many. I had to baby sit the printer anyway because of failed filament loads during color changes. Finally I think my MMU is shot. All it does is flash all the lights red. I spent to much time trying to work with the MMU and decided it's just not worth it for as much as I needed complex multi color prints. As far as debugging the FINDA, I'd remove it from the MMU and see if it's still at 1. The FINDA has a light in it that's on when it's at 0 state. If you put something metal at the tip (pliers, screwdriver, etc.) the light should go out. If that's not working, there's something going on with the electronics or software. If you can You could test the sensor by removing it and it's wires from the MMU, opening the main electronics box an the MK3S and plugging the FINDA into where the PINDA is plugged in. Turn the printer on and see if PINDA is actually going on and off like it should. I doubt if the FINDA is bad. If something in the electronics of the MMU is bad, there's probably only option. Replace it. I'm not sure if PRUSA would send just the circuit board but they probably would. Most likely it's software, with all the issues you read about in the blog. I wonder if anyone has tried the 3rd party firmware updates as a fix for the FINDA. That might be worth a try. Hopefully your FINDA is working and it's just some debris in the MMU that's causing a false reading. You'll know this when you pull the FINDA out and test it. Connectors are sometimes a problem. You can test that by just unplugging and plugging the connector back in. I doubt if that's a problem but it's just something else to check. Hope yours turns out to be an easy fix.

RE: FINDA probe stuck at 1

I am suffering from the same problem that colleagues report here.

It has been almost 9 months after purchase and I have never been able to successfully print a colored object.

I initially bought an MK2S and then bought the MMU1 and now recently the MMU2.

I feel very disappointed with these updates that were sold to the PRUSA printers (MMU1 and MMU2).

But the main issue is that I feel cheated, because I thought I had bought a printing solution and apparently I bought an infinite problem.

Because I spend more time using forums correcting problems for defects that in my view should have been seen by the team that developed the product during the homologation stage.

I already had to change the heat sensor of the printing table, the sensor of the print head, the printing table and now I wonder what will be the next piece?

I apologize to everyone for the outburst.

RE: FINDA probe stuck at 1

@fabio-f3

My choice was easy. The MMU failed completely. Nothing but all lights flashing. I disconnected all the cables on the MMU and ran as single filament printer. The MMU was a nice novelty but what a pain. Even running single color prints became a lot more trouble. I'm very happy with my printer again with no MMU.

RE: FINDA probe stuck at 1

I am also having the same issue with FINDA probe being stuck at 1.

I built and installed MMU2S, loaded filaments, and able to do first layer cal for each of the five filaments. I was even able to start a multi material print. Then I went to unload filament 1 to put in a different filament, and my MMU has been bricked since. When I try to load or unload filaments all of the LEDs will flash red. 

I have taken the MMU apart to check for stuck filaments, currently no filaments are loaded and it is having this issue.

Looking at the sensor info under support the FINDA is always stuck at 1 no matter what I try.

I have tried to remove the FINDA from the selector to manually activate with metal and the FINDA is stuck at 1.

I have even tried unplugging the FINDA cable from the MMU board all together...FINDA stuck at 1.

I did a full factory reset for both the MMU and the MK3S....FINDA still stuck at 1....

Any suggestions or solutions on how to overcome FINDA being stuck at 1 are greatly appreciated.

Thank you.

RE: FINDA probe stuck at 1

I think I have a bad probe, going to try a new one. I shorted the FINDA sensor input pin to ground on the MMU board and the LCD displays 0 successfully. 

RE: FINDA probe stuck at 1

I have had this twice, unfortunately. First time Prusa support sent me a new FINDA which fixed the problem. Second time was about a week ago, I again replaced the Finda (my dime this time, I didn't bother asking support) and it is again working. Not sure what I am doing wrong, I am gentle with all connectors, there is enough slack and I am not resting the door on the cable. In either case it's working again!