Autoload Filament stopped working  

RE: Autoload Filament stopped working

the sensor may need adjusting, or a washer like this
https://www.thingiverse.com/thing:4665750      or
https://www.thingiverse.com/thing:4006603

regards Joan

RE: Autoload Filament stopped working

I have a similar problem. My Prusa i3 MK3s stopped feeding in mid-print. It claimed the print being finished, but the last ~20 layers were missing despite filament being loaded. At first, I feared some clogging, so I cleaned the whole hotend, switched out the nozzle and the PVC tube, but when I am trying to feed filament, it does not detect it, and when I try to print, it doesn't feed any filament. I don't even manage to push the filament deep enough so it melts in the hotend and drops out. Then I tried to test the filament sensor, but it seems not to detect any sensor.

RE: Autoload Filament stopped working

Check the connections on the filament sensor, you should have +5volts, ground  (0Volts) and the signal wire
if 5v and ground are present, the signal wire should show nearly 5 volts or nearly 0 volts, depending whether the filament sensor is at rest, or activated. and the filament sensor value in the LCD Sensors menu, should toggle between  0 and 1 

it's possible that one of more of the filament sensor wires is faulty. they can fracture due to fatigue, from all of the flexing

Joan

RE: Autoload Filament stopped working

I'll check the voltage and come back with results. Thank you for the hint!

RE: Autoload Filament stopped working

Good Luck

Joan

RE:

The filament trigger can get stuck as it is a very close fit. When facing the printer try backing off the screw which is top left of the filament loading block and next to the sensor connection.  For reference it passes through into the stepper motor. It may only need a quarter or less of one  turn to do its trick. 
This was advice from prusa support when my sensor was unreliably detecting filament runout. 

RE: Autoload Filament stopped working

I checked the voltage between the pins labelled "+5V" and "GND", and I didn't measure anything. I checked also the reaction of the detector after dismounting it from the hotend, by moving a sheet of plastic between the sensor sender and receiver. For good measure, I also tested if the lever moved by putting filament into the hotend, which it did.

Then I measured if at least, I get +5V readouts from the plug of the cable, and I got a resounding 0.00 V.

RE: Autoload Filament stopped working

Looks like a cable fault. 

Check voltages on motherboard 

Joan

RE: Autoload Filament stopped working

I finally had the time to look into the filament sensor mystery more deeply. Root cause was a loose cable on the motherboard. I reseated the plug, fixed the cable with a tie, and now the sensor reports data again.