I couldn’t find a similar issue on this forum, so I’m posting here.
I replaced the MC board because my H2D printer stopped powering on. After replacing the board, I performed a factory reset and tried to print something.
I have an AMS 2 PRO connected to the right extruder. However, when I tried to print, it failed to load the filament properly. The filament reaches the right extruder, but the motor that should push the filament into the nozzle is rotating in the wrong direction (counter-clockwise). As a result, the filament doesn’t enter the nozzle.
After several failed attempts, the printer gives me the error: “Filament buffer signal is abnormal.”
I then connected the AMS 2 PRO to the left extruder, and it prints perfectly. So I believe the issue is specific to the right extruder.
I also removed the right nozzle to check for jams, but there is no broken filament inside. I made a video showing that the filament drive wheel is spinning counter-clockwise when it should be pushing filament into the nozzle.
It’s turning the right way before it turns backwards. I know you said you removed the nozzle to see if there were any jams - but I suspect your jam would be above the nozzle / in the extruder gear area.
I would take it apart further than just the nozzle and look. I bet you find a jam in there somewhere.
I tried to insert the filament manually. If I push it gently, it doesn’t go in, but if I push it firmly, it goes down and comes out of the nozzle (preheated to 220°C).
I’m having the same exact issue I can’t get the ams 2 or ams ht to load in either nozzle it’s driving me insane. Does the same exact thing extruder spins the wrong way if anyone knows please help.
Yes they are setup correctly and ive messed around with making the ams ht and ams 2 go both into the left and both in the right an no combination works did a cold pull on both sides and nothing. Something has to be seriously off i dont believe its a clog error cause of the cold pulls, just the extruder spinning the opposite way no matter what even after factory reset.
Have you double checked your wiring on the board yet? I don’t even know what it looks like so I’m just spitballing here, could the wire for the right side be installed 180°?
The board change is a good point!
But I would rule out the cable twist of the motor, because it prints fine on the left, but not on the right hotend - and it’s just one shared extruder motor.
But maybe the cable of the sensor for ‘which extruder is down’ is the issue:
I think it’s not a safety integration level hardware with redundant signal lines. So there might be only one wire to the hotend sensor switch with a pullup resistor on the board. Imagine left extruder down is a contact ‘open’, the board sees ‘high level’, resulting in logical ‘1’. And if right extruder is in use the contact gets closed, resulting in ‘low level’ and logical ‘0’ for the software.
But if that wire is broken or not connected, the software sees ‘1’ every time, assuming the left extruder is in use and turning the motor counter clockwise to push filament towards the nozzle…
this is a known issue and there are numerous posts in numerous forums about this problem. the H2D appears to be WAY too strict with reading the buffer signal and aborts the loading procedure much too early. I’m currently unsure how to fix this either.
Happens also with PVA in the left nozzle, if you feed it manually everything is ok, but when is has to come from the ams ht… you better switch the pva to the right one… she makes the try to get the filament “super fast” and as you say she aborts the operation and starts spining backwards, so yeah, probably the problem of this guy is the filament sensor in the nozzle of the buffer or whatever
Literally have the some problem.
I also observed that everything using the Bambu Handy app after switching the AMS unit to a different nozzle tube on my H2D, confuses the printer
I’ve had the same problem and think have a solution. when you slice use the manual mode to assign filaments. Do NOT use “Filament-Saving Mode” or “Convenience Mode” I think those options generate incorrect G-Code that turns the feed wheel the wrong way when trying to load the material.
I will try that later today but that cannot be a proper solution. While my support ticket is taken ages to even get them to understand what my problem is, I think it is frustrating