Heat bed failure
Good morning,
Last night I got a heat bed thermal runaway error while I was away from the machine.
This morning the heat bed will not heat at all. The info screen shows 20 degrees.
I believe I have a wire break due to movement or just a bad heater.
Is the heating element beneath the gold foil on the bottom of the bed?
(Two large white wires leave the connector at the back left and lead to it).
I have an unrelated problem as well. After a week the printer makes a click sound as the print bed travels front to back.
It does this with the power off so it's not electrical. It's not reliably always at the same physical position in the bed travel but it's close.
I'm having trouble visually finding the issue. Some one mentioned liner bearings.
Would those be bits between the print bed and the two metal rods beneath?
Thanks for any help. This is my first Prusa.
Re: Heat bed failure
Hi Jay,
the heater is an integral part of the black Bed printed circuit.
the item below the gold tape is the thermistor which measures the temperature of your heatbed.
assuming that your room temperature is 20Centigrade, then it would appear that your thermistor is working.
the heater wires can 'Work Harden' and suffer 'Fatigue breakages' from the back and forward movement of the bed.
it is possible, but less likely that a fuse has blown on the Einsey board. you could check this if you have a multimeter test meter... if you take the fuse out of the einsey board, the fuse should measure short circuit on your multimeter ohms scale.
less likely again is a failure of the einsey heatbed driver circuit... while the heatbed should be heating, you should be able to measure 24 volts across the heatbed screw terminals.
clicking sounds may be caused by a broken wire in the bed wiring loom causing the ends of the wire to click against each other
breakages can occur anywhere, but are most likely at the ends of the heatbed cable, mine broke exactly at the end of the wire. where it was soldered onto the heatbed PCB
I checked the continuity of my cables with my multimeter, and confirmed the wire was broken between the einsey and the heat bed
I hope you can sort the problem and get your printer back in business soon.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Heat bed failure
Joan, you're so incredibly wise and educational. I read your posts with great satisfaction 😀
Bear MK3 with Bondtech extruder
Re: Heat bed failure
Thanks Joan. Great explanation.
I'll get out the multimeter and check for the fuse, continuity on the wires, and the print bed.
At least I'll be able to figure out what's broken. Hopefully the heating element didn't fry!
Re: Heat bed failure
I'm pretty sure I have it figured out. Thanks Joan!
Re: Heat bed failure
That would do it!. 😯
good luck
you might consider getting flexible silicone wires for a future update
the bottom wires are original prusa, about 22 filaments each, more flexible than standard 7 filament wires, but not as flexible as the upper wires that have over 200 filaments inside a flexible silicone sheath! (radio control cable 16AwG off ebay!)
mine broke in an identical position.
the new cable clamp offers better strain relief!
regards Joan
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Heat bed failure
thanks for the kind comments...
I believe in sharing experiences to help and encourage others! as I have been helped and encouraged by others!
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK