TL,DR: Filament motor died. Tested motors and drivers, all work. Reloaded firmware, no help. Is it the Mainboard?
During a print, the extruder motor started clicking. With each click, the filament that went into the printer would jump back out. I’m used to seeing that if my flow rate is too high or the nozzle is clogged, but this time neither was the case, and the clicking was actually more rapid than it usually is during these situations. Thinking the hobbed bolt was clogged, I took the mechanism apart and it was pretty clean. Reassembling and testing with “Move Axis”, the unloaded extruder appeared to move normally. But once I inserted filament, the clicking/non-feeding returned. And this was with the PTFE tubing not yet reconnected so the filament was exiting the hobbed bolt fixture into empty air. Since it seemed that the motor, though appearing to work when unloaded, was now somehow “too weak” to advance filament, I decided to rule things out by checking the motor drivers on the mainboard. After cycling power to do this, I noted that the extruder motor had now stopped working altogether. The EXT1 driver worked for all other motors but none of their drivers worked in EXT1. Then, I swapped motors. In the same way, the extruder motor worked when plugged into other motors’ sockets, but no other motor worked when plugged into EXT1. This appeared to have established that the problem was neither motors nor drivers.
The final clue came while watching the mainboard during “Move Axis”. Normally when moving each motor, a red LED lights up next to that motor’s driver. However, the LED at the extruder driver does not light up under any circumstances.
The next steps I can see are: reinstall the firmware, and then physically check the mainboard for shorts or burned components. But while I’m amusing myself with this, does anyone in the forum or at Velleman have any ideas or suggestions that may help? Thanks in advance!
Yes, the loose pulley was a problem in the first days of the printer, but that had very different symptoms. Right now the motor (ANY motor) just doesn’t move when connected to the extruder controller, so the process doesn’t get far enough along for a loose pulley to make itself known.
New firmware didn’t work, and there’s no obvious signs of damage or burning to the mainboard, BUT I did notice something odd… the location of two diodes (DZ5 and DZ6) don’t just look empty, they look as if they were installed but then removed. Is that correct, and if so, is it significant?
DZ6 is in the circuit for the bed-thermistor and DZ5 is in the Extruder2-thermistor circuit looking @ this schematic.
Could DZ5 cause a bad temperature reading? Which makes/shows that your nozzle is to cold to get any fillament melting?
It’s a failsafe in the firmware to block the extruder motor untill the nozzle is hot enough, might be related?
Can’t exactly say if it is really significant… Cant compare with my Motherboard at this time. Maybe someone else could?
Very interesting, thanks for the graphic. But even if the filament feed was locked because of extruder temperature, I should still be able to move the filament motor by using the “Move Axis” menu command, which no longer works.
OK, and I would have assumed “DZ” stood for “Diode: Zener”. But this is not only over my level of electronics knowledge, it also seems academic cos the bloody thing DON’T WORK!
Both diodes have been removed from earlier boards.
Newer boards do not feature these diodes.
Reason: leakage current caused a temperature readout on the display, even if no sensor was connected to the board.
This was undesired since the firmware was not able to detect a disconnected temperature sensor.
If desired, you can return the board for inspection/repair.
Wrong Way (and others, which means I’ve explained myself badly): The problem is not with the extruder at all, it is with the motor that feeds the filament. It has stopped moving. Regardless of any condition or temperature of the extruder (meaning hot end and nozzle), I should always be able to manually make the filament feeder motor move using the printer’s built-in “Move Axis” command. It no longer does this for me. The motor itself works when used elsewhere on the mainboard (x-axis, y-axis, etc.). Similarly, the stepper driver works when used on other motors of the printer. However, no motors work when plugged in as the filament feed motor, regardless of whatever stepper driver is used. This tells me it is the mainboard. I reinstalled the firmware, nothing changed, so it’s not a software problem. That leaves one remaining explanation - something on the mainboard has failed. This is beyond my ability to fix so I’m going to take VEL417’s kind offer and ship the sucker in for repair or replacement.
I just tried that on my K8400.
The display changes but the motor does not move.
I think this is a fail safe.
You should try to heat the print head to 190 before you try to move it
I just tried that on my K8400.
The display changes but the motor does not move.
I think this is a fail safe.
You should try to heat the print head to 190 before you try to move it[/quote]
Volguus,
I believe very much, that one of the 4 motor wires got a weak electrical contact very likely at the plug.
Can you check the plug pins if they look black ? Then use a file on them to brighten their surface ?
you could actually exchange the cables on the plug sockets to determine if the problem is with the male or with the female part.
