Need help with under-temp HotEnd, Prusa i3Mk2- Doesn't hit target temp
Hi guys.
I'm having a strange issue with the hotend of my MK2. No matter what temperature that I set for the temp of the hot end, on pre-heat the temperature raise to between 5 to 10 degree of target and then just cycles on an off, never reaching the desired temp.
If I set the desired temp as 200 degrees, the hot end will reach 195 and then waiver around that temp. If I set the temp to be 210 it will hover around 200 to 205. It never reaches the actual temp and then the print will never start.
If I select ABS pre-heat and then let it come up to a temperature above the target that I really want. I can then quickly start a PLA print and once it *Cools* to the temp it will start, but then the temperature will eventually fall below the target temp and the print will fail. (print unstable)
Any thoughts on how to remedy this? I've replaced the extruder tip, and I've also removed and re-seated the temperature probe. All the cables appear attached and there doesn't appear to be any physical issues with anything in the extruder area.
I've had nothing but issues with my out of the box Mk2 since I've got it and I'm trying really hard to make it a useable machine before I throw it into the pile along with a flakey Makerbot. I had (and still hold out) high hopes for the MK2. Previously I've had issue with shifting layers and other things, but I'm getting those worked out one-by-one. But this issue has now come up and I' can't seem to find a way past it.
Any thoughts would be most welcomed.
Ryan Johnson
-NewRuleFX
[email protected]
Re: Need help with under-temp HotEnd, Prusa i3Mk2- Doesn't hit target temp
Have you tried doing the PID calibration for the hotend?
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…
Re: Need help with under-temp HotEnd, Prusa i3Mk2- Doesn't hit target temp
I did indeed try the PID calibration.
It appeared to complete successfully.
-Ryan
Re: Need help with under-temp HotEnd, Prusa i3Mk2- Doesn't hit target temp
Could be any of the following
- Physically damaged or mechanically compressed thermistor
- Wiring: intermittent cable or board connector, or loose pin crimp(s); short between the hot end heater power or ground lead and either thermistor lead in the cable bundle; thermistor floating (open) ground
- Modified or otherwise damaged firmware in Flash
- Defective controller PCB - cold solder joint(s), solder short, bad RC component, incorrect MCU analog reference, bad MCU
My gut says firmware, so this is how I would proceed. First, reflash the firmware with an absolutely stock BINARY from the Prusa website. If that does not work install a new thermistor with a new cable and connector. I suggest you purchase an assembly from Prusa to make sure you get the right parts and be very careful not to over tighten the thermistor hold down screw. If both firmware and thermistor fails to solve the problem, remove the controller PCB and visually check for shorts and bad (cold) solder joints in the path between the thermistor connector and MCU ADC pin. If you are able, test trace connectivity and test the passive components in that path. Failing that swap out the PCB with a new one. It pretty much has to be either thermistor/cable, firmware, or controller PCB.
Re: Need help with under-temp HotEnd, Prusa i3Mk2- Doesn't hit target temp
Thank you Mark for taking the time to detail this information.
I'll work through those steps.
I haven't looked inside at any of the PCB's yet. (I purchased this as a fully assembled unit) I've been weary to start opening everything up and messing up the alignment. It appears that might be unavoidable.
Hopefully it's just the thermistor.
Does anyone know a source in the US that sells the correct "Prusa approved" thermistor? I'm looking to save shipping time and get back online. Is see them everywhere online, but if there's a critical difference that I should note, I do not know of that.
Thank you.
Re: Need help with under-temp HotEnd, Prusa i3Mk2- Doesn't hit target temp
Filastruder: https://www.filastruder.com/products/v6-volcano-cartridge-style-upgrade?variant=20942512644 - select thermistor only.
But note it comes with a short lead and that it is best soldered onto the existing lead.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…