Heat Bed Temp dropping  

Re: Heat Bed Temp dropping

Heat bed thermistor?

Re: Heat Bed Temp dropping

That is possible. But I am not sure how I would troubleshoot an intermittent problems like that.... besides changing out the sensor (might order one just in case)..

Re: Heat Bed Temp dropping

Hi Carl,
if you pre heat the printer, then wiggle the cable bundle at the back of the bed, you may see the display temperature changing. if this is happpenning, then you probably have a fractured cable. frequent bending can cause this.

it's possibly because the nylon support filament has become dislodged causing localised stress.

If the temperature changes rapidly, then it's likely to be the thermistor cable if the temperature changes more slowly, it's probably the heatbed power cable, Mine fractured right at the soldered connection.
I replaced it wit flexible silicone wire off ebay, as used for RC Models.

Regards Joan

Re: Heat Bed Temp dropping

or the thermistor wire is pinched and is breaking. preheat the bed and then move the bed by hand back and forth. does it stay stable when not moving and fluctuate when moving? if so the thermistor wire is breaking and likely will stop working at some point. on mine i printed the new heatbed cover and when putting it together the thermistor wire slipped off just a little to the side, got crushed and then flexed until it broke. I did some cutting and soldering and backup and working.

if you do this i would suggest heat shrink to cover your wire repairs. much better than tape.

Re: Heat Bed Temp dropping

I think this may be the problem I'm having. I was having a lot of trouble getting my prints to stick to the bed, and now I'm realizing it wasn't a calibration issue, as the bed has stopped heating at all. I'm still very new to this, and when I tried to trouble shoot, I opened the EINSY board cover, checked that everything was correctly connected, then turned the printer back on. I selected preheat to see if it would heat the bed up, and sparks came out of the connection point on the board (a little adrenaline burst there!).

Does this sound like my connection wire got bent/broken?

I have it in an enclosure that I built following the PRUSA tutorial for a lack table, and it seems it bumps the back of the case sometimes, which would cause that I guess.

Re: Heat Bed Temp dropping

Hi Sharon,
Sparks are never good unless you are welding. 😯

Chances are you have a problem with the heatbed power wires, and possible the heatbed power fuse!

see my post higher up.

regards Joan