Fan not spinning  

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boulland.michel
(@boulland-michel)
Eminent Member
Hello
I just finished assembling my MK3S and the fan test failed.

Extruder fan = Ok

Print fan = see message below

It's amazing because this fan works (I see it running)!
I checked the connection several times:
- Extrude fan: black sheath, 3-wire black, red, yellow. Connected to the right of Extruder heater
- Front print fan: without sheath, 3-wire black, red, yellow. Plugged right Extruder fan

What do you think ?

Posted : 21/05/2019 10:29 am
Vojtěch
(@vojtech-3)
Honorable Member

There doesn't seem to be any 'message below'. What exactly happens during the initial test? Note that you have to respond 'NO' at one point to the question to pass the test.

Posted : 21/05/2019 11:17 am
boulland.michel
(@boulland-michel)
Eminent Member

Hello Vojtěch,

First screen:

Fan test

-----------------------------

Extruder fan:   OK              ( the Noctua fan turns )

Print fan: I-I-I-                    ( the front fan turns  - I see it and I hear it)

 

Second screen:

Fan test

Left hotend fan?

  Spinning

>Not spinning

What should I answer ?

1 - if I validate    >Not spinning   I have a new message: "Self test error! Please check: Front print fan? Wiring error Self test failed."

2 - if I validate  >Spinning (with the button I go up a line) : I have a new message: "Seft test error ! Please check: Front/left fans Swapped" Self test failed"

On the motherboard: the cable with a black sheath with 3 wires black, red, yellow is plugged to the right of Extruder heater connector; and the cable without sheath with 3 wires black, red, yellow is plugged to the left of Filament sensor.

What am I doing wrong?

Posted : 21/05/2019 1:25 pm
Vojtěch
(@vojtech-3)
Honorable Member

I think you have a problem with the yellow "tacho" wire of the print fan. That's what the fan uses to report rotation speed back to the printer. It seems the printer is trying to spin the fan, the fan spins, but the printer doesn't get the information back that it is spinning.

You can verify that by swapping the fan connections and pretending to the printer that the fans are the other way around. The print fan test then should pass and the extruder fan should fail.

In any case, check the cable to the print fan for damage or manufacturing defects. Most likely at the connector or at the fan (under the sticker). If you have a continuity tester, check that there is a connection between the connector pins and the fan PCB.

Contact Prusa on Live chat and they'll send you a new one.

Posted : 21/05/2019 2:25 pm
boulland.michel
(@boulland-michel)
Eminent Member

1 - I checked the continuity of the yellow wire => it is ok
2 - I redid the selftest and I validated the lines like this:
2.1:     > not spinning => I valid
2.2:     > not spinning => I switch with spinning and I valid

!!!!! Yes !!!! The printer is "happy" and write OK for the two fans.

I leave the selftest continue with the verification of the lengths x, y, z and the temperature of the bed and the extruder.
Everything is OK.
Can I continue with the xyz calibration despite the problem of starting?

 

Posted : 21/05/2019 3:14 pm
Vojtěch
(@vojtech-3)
Honorable Member

Yes, you can.

Posted : 21/05/2019 11:16 pm
hairy jaws
(@hairy-jaws)
Active Member

Hello

i have ran into the exact same problem after upgrading to mk3s and had to do exactly the same thing to resolve the problem. could this be a firmware error maybe ?.

Posted : 25/05/2019 9:48 pm
djholm
(@djholm)
Active Member

Same problem here. I tested and verified there was continuity of red, black, and yellow wires from fan (under paper sticker) to connector (detached from Einsy). Haven’t verified continuity to the circuit board. In self test I indicate that both fans are spinning (they are) and all else works.  The PRUSA badge prints fine, with the printer fan activating midway, and I do not get a fan failure error. So it seems the RPM check is working during a print (assuming that is how a non-spinning fan is detected).

In Settings/Temperature/Fans I can dial up any speed and it works. Of course both fans spin, and I don’t know if the printer fan RPM is checked.  Guess I will look at the firmware code. PrintSolid coincidentally has a sale on replacement fans so I’ve ordered a couple spares. I’ll be able to plug into the Einsy without undoing the cable bundle and see if the problem is following the Einsy (i.e. by verifying signal on yellow RPM line on the test bench). 

This post was modified 2 years ago 2 times by djholm
Posted : 18/06/2019 11:59 pm
djholm
(@djholm)
Active Member

An update (second day of using my new MK3S).   I swapped at the Einsy board the extruder and printer fan cables (i.e., plugged the printer fan into the left, extruder, jack on the board, and the extruder fan into the right, printer, jack).  I then ran the self test.  The printer fan, posing as the extruder fan, passes - so the RPM sensor is alive and well.  The extruder fan, posing as the printer fan, fails. 

This points to either a problem with the Einsy board printer fan connector, or with the firmware.  All models have printed successfully, both PLA and PET (so different extruder temperatures) so presumably the printer fan sensor check is working during printing, which suggests this is simply an issue in the self test.

Posted : 19/06/2019 10:34 pm
jord
 jord
(@jord)
New Member

I just completed the Assembly of Prusa MK3S , and as i run the video for the calibration, I get this same issue. I turned it off and swapped the cables, thinking i made a mistake (but verified that on the picture that the black sheathed connector is on the left and the loose one on the right) swapped it anyways. Run the test again, same error , but both fans was spinning fine, but I can go on any further on the calibration. Suggestions!

Posted : 28/06/2019 4:43 pm
Dave Avery
(@dave-avery)
Honorable Member

the tests are a bit confusing - make sure you check the fans again at every step in the test. they change which fan is running between questions.

 

this changes in firmware 3.7.2. now the extruder fan test is tacho only and then they run a tacho test on the part cooling fan. afyer that they ask if that fan is spinning to make sure the tacho test was on the correct fan

Posted : 28/06/2019 4:54 pm
djholm
(@djholm)
Active Member

If you are running the 3.7.1 firmware, as I am (I built my mk3s just over a week ago), during the selftest the printer successfully finds that the extruder fan (upper fan) is running, but fails to detect that the print fan (the lower fan with the nozzle) is running.  The little propeller on the LCD spins during this test and eventually it indicates that the fan was not detected.  Assuming your printer fan is spinning, to proceed further with the calibration answer the questions on the LCD.  If I recall correctly, with the print fan spinning it will ask if the upper fan (extruder fan) is spinning.  Say "no".  Then it will ask if the lower fan (print fan) is spinning.  Say "yes".  The calibration will then continue.  I've been happily printing for the last 10 days after seemingly failing the fan selftest; with PLA gcodes the printer fan spins up and works just fine.  So this looks like just an issue with the selftest fan dialog.

I've just checked-out from github the firmware, and I see between 3.7.1 and 3.7.2 that there are many changes in ultralcd.cpp with respect to the fan tests.  I want to change nozzles later today and so would need to re-calibrate Z anyway, so I'll go ahead and flash 3.7.2 and will report back.

Although I was nervous that the apparent print fan selftest failure suggested either a bad tachometer on the fan itself, or an issue in cabling (swapping print and extruder connections eliminated this), or an issue on the Einsy board, using Temperature/Settings/Fan and seeing that the fan speeds changed on command convinced me everything was OK.

Posted : 28/06/2019 7:01 pm
djholm
(@djholm)
Active Member

I also meant to paste this in from the 3.7.2 release notes:

Autonomous fan self-test

In the previous release, the user had to assist during the fan test. Now, the self-test is fully automatic.
Printer spins up each fan from low to the max RPM and measures the values. Since both fans on the extruder
have a different range, it is possible to detect, whether they are connected to the correct socket on the
board and whether the fan is able to reach its max RPM.
 
Posted : 28/06/2019 7:12 pm
djholm
(@djholm)
Active Member

I can now confirm that the 3.7.2 firmware release fixes the issue in the fan portion of the self test.  The extruder fan portion is very quick.  The printer fan (lower fan) portion takes longer; the propeller spins for at least 20 seconds, and you can hear the printer varying the speed of that fan during the course of the test.

Posted : 29/06/2019 2:45 am
admpc
(@admpc)
New Member

Hi everyone, I have a MKS+, I managed to get some (like 3 or 4) prints and then I had a bad clog. I changed ptfe tube and cleaned up the bondtechs, other than that everything looked fine. Now i'm not able to finish the first layer leveling test: the printing fan does not start and the filament does not stick to the bed but adds up on the nozzle till it clogs (actually I stop before that happens). I tried with bot pla and petg, but the "front fan" does not start at all during this (while I don't recall if it did before). So I think the problem is this, but from the menu i can get that fan to spin, so it is not an electrical problem.. I just flashed last firmware 3.9.3 and tried again, but the problem remains.

Any suggestions??

Posted : 07/05/2021 5:32 pm
3Delight
(@3delight)
Moderator

Please do not hijack other people topics with different issues, create a new one in the relevant section.

Posted : 07/05/2021 11:29 pm
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