Filament detector overheating  

Re: Filament detector overheating

I have been scouring the internet for information on this tiny sensor and I cannot find any information that comes close to the so called "Laser" sensor on the MK3. If you know the source of this sensor I would sure like to here about it.

Testing the sensor with glass between the sensor and filament is easy enough to test. A microscope slide thickness of glass like an eyedropper tube would work for a test. Pull out the sensor from the extruder and try it!

Re: Filament detector overheating

I have been scouring the internet for information on this tiny sensor and I cannot find any information that comes close to the so called "Laser" sensor on the MK3. If you know the source of this sensor I would sure like to here about it.

The source code implies its called pat9125. It's rumored to be this one: http://www.pixart.com.tw/upload/PAT9125EL_GDS_V1.2_31052017_20171011150843.pdf

Re: Filament detector overheating

Thanks for the link. I will check it out.

Re: Filament detector overheating

My sensor failed today. Just stopped working. The menu now says N/A on the sensor menu.

Support is sending me a new one.

As far as I have been able to see the part number is PAT9125SEL but I’ve not been able to find a source other than prusa.

I wouldn’t mind having a few spares. The price on the prusa page isn’t too bad. But postage is two times the cost of the sensor.

My sensor still looks ok and didn’t overheat. It’s just not working.

Checked all the wiring and cleaned the sensor. Still failed the self test. Fortunately this doesn’t impact printing.

So I am now waiting a week or so for a replacement to arrive.

If anyone knows a place to get these other that direct from prusa, I would be great full.

Jason.

Re: Filament detector overheating

My sensor failed today. Just stopped working. The menu now says N/A on the sensor menu.

Be sure to unplug the sensor, it still gets power even if the menu says N/A. If it hasn't gone up in smoke yet, this could save you some extruder-housing-melting headaches

Re: Filament detector overheating

My sensor failed today. Just stopped working. The menu now says N/A on the sensor menu.

Be sure to unplug the sensor, it still gets power even if the menu says N/A. If it hasn't gone up in smoke yet, this could save you some extruder-housing-melting headaches

Will do.

Thanks for the tip.

Jason.

Re: Filament detector overheating

I just got an email response from support about the sensor fail.

They asked me to check the continuity of the 4 wire connector from the sensor to the board. Which I did and all were ok. Also no shorts between any of the wires either.

They also asked me to send them a video of the printer screen to show it saying N/A.

I have done this.

Hopefully they send a new one.

I think there is a design flaw in having the sensor so close to the hot end.

I think mine may have failed when I had a filament run out detected and the printer tried to unload the filament to allow a new one to be loaded. It jammed during the unload.

I think the jam is when it got damaged.

I believe the sensor should have been located a little further away from the hot end and this might have stopped some of the issues with blobs of hardened filament being ripped past the sensor and damaging it in the process.

Fingers crossed they send me a new sensor.
This is my only complaint so far.

I will update this thread With their response.

Jason.

Re: Filament detector overheating

Here we are a week later and no further response. Not happy.

Jason.

Re: Filament detector overheating

I finally got a response. They are sending me a new sensor and extruded body. Apparently some of the early extruded bodies were slightly incorrectly printed leaving the sensor too close to the filament path.

Will Report back once I have them both installed.

Jason

Re: Filament detector overheating

Hm...this reply made me think...does this mean that those who have early models it's best option to re-print extruder and change it?
And... up to when (date...?) they consider "early model"?

Re: Filament detector overheating

I have no idea what they consider early. They only said that some of the extruder bodies were badly printed.

Still waiting for the replacements to show up.

Re: Filament detector overheating

An update.

The new sensor and body arrived today. I can see absolutely zero difference between the extruder body that I have now, and the replacement one that was sent. So I installed just the new sensor.

It was immediately recognized by the printer and is now working as expected.

I think the problem I had was a filament jam when unloading when I did the first “test” of the filament run out sensor.
It detected the run out, then promptly jammed when doing the unload.

I think that jam is when mine was damaged.

No matter the reason, it’s now fixed.

And I will not rely on the sensor for filament run out in future.
I will try to only do manual filament changes.

Jason.

Re: Filament detector overheating

Dear all,
I had the same problem like described here (MK2.5 upgrade). The sensor got very hot as well - Prusa send me a new sensor very fast - thanks for that.
Additionally I got the Information that within about two weeks a redesign of the printed parts of the extruder will be available.

--> I will wait for installing my new Sensor until I have redesigned parts.
Additionally I plan to put in a fuse in order to make the sensor a bit more safe.

I measured the following currents at the sensor's power supply:

Faulty Sensor (rev. 0.2): 200mA
Sensor OK (rev. 0.2): 4mA

Birk

Re: Filament detector overheating

Finally finished my 2.5 upgrade today, and when running the z height calibration, my extruder started clicking. It wouldn't reliably feed at all. After a whole bunch of messing around I noticed that the PLA filament was getting soft and melting near the filament sensor. The sensor was hot!

I dismantled the sensor from the extruder, and sure enough, the lens on the sensor was shattered. Photo attached. I also noticed that there were remnants of the shattered lens around the PTFE tube going to the extruder.

So I tried running without the sensor. Extruder still jammed. I then replaced the nozzle, and was able to finish calibration and run a benchy.

My guess is that some shards from the sensor made their way into the extruder and clogged the nozzle.

I immediately disconnected the sensor on my MK3 and plan on taking it out.

I honestly don't care if Prusa sends me a new sensor for free for my mk2.5 upgrade. This just seems like a fire hazzard. Why should it get this hot!?! Whether it failed on it's own, or had a physical impact from a filament blob, it scares the heck out of me. I'd rather have a simple contact mechanism than a fancy sensor that gets hot.

Dont get me wrong, I'm a prusa fanboy. My mk2s ran for an entire year nonstop with zero issues which is why a bought a second. But I've had nothing but issues with the "smart features" on the MK3 and turned them all off.