Heatbed and extruder won't heat up
Hi,
I have an issue with my new Prusa i3 MK3. The printer worked perfect the first few days after assembly, but then I got a THERMAL RUNAWAY error two times during two different prints. After that I can’t get neither the heatbed nor the extruder to heat up. Sometime it heats up for a short while (1-3 min) and then shuts off and I get a BED PREHEAT ERROR or PREHEAT ERROR. Other times it will not even start the heat up. It seems that if you let the printer rest for a while there’s a bigger chance to at least have the heating started. If you try immediately after an error it is less likely to start the heating again.
These are the things I have tried to solve the problem:
- Factory restore (several times).
- Re-flashed the latest FW (several times).
- Flashed an older FW version.
- Have tried both PREHEAT (bed and extruder together) and nozzle and bed separately (via SETTINGS -> Temperatures).
- Performed a PID calibration (when I could get the heater to heat up long enough).
- Checked all fuses: all OK (measured with multimeter).
- Disconnected power panic cable.
- Disconnected all cables on EINSY board except PSU, LCD, extruder + bed heater (also disconnected them separately and vice versa), thermistors and extruder fan.
- Checked both thermistors: both OK. Displays room temperature correctly, responds well when tested with a hair dryer and when the heat up is ongoing. Also visually inspected. The ambient and PINDA thermistors also shows good values.
- Measured heatbed and extruder heater resistance: both OK. Bed shows 3 Ohms which I believe is correct and the extruder heater cartridge shows around 15 Ohms which seems to be close enough (should be 14.4) for the E3D-v6 24V40W hot end according to this page: https://wiki.e3d-online.com/E3D-v6_Assembly
- Tried a new PSU (Prusa sent me a new one after contacting them last week).
- Disconnected the EINSY board from the printer and ran it from a table.
- Visually inspected the EINSY board without finding anything odd. All LEDs' are lit correctly when the fans, heaters etc. are enabled. Voltages measured correct. 23.8V input and similar for the heaters when they are enabled.
So I’m out of ideas here. I have contacted Prusa again, but this time they wanted me to send an email instead of getting support via the online chat like the last time and I haven't heard from them for several days. So in the meanwhile I wonder if you might have some suggestions.
- Is there any sensor on the EINSY board that might trigger and force the bed/extruder heater to shut off? Can I disable it in that case?
- Can I read out any log to find information about why they're shutting down?
- Or is the EINSY faulty in general (MCU etc.) and need to be replaced?
Any suggestions are most welcome.
BR
Robert
Re: Heatbed and extruder won't heat up
hi Robert,
do the hot end and bed temperatures look reasonable at rest?
are the thermistors both firmly fixed where they ought to be?
if you use a hair drier on hot, to heat the extruder and the bed, do you see the temperatures raise on the LCD?
the einsy checks the thermistors before turning the heaters on,
if the thermistor is cold or open circuit, you get a min temp eror
if the thermistor is exceptionally hot, or short circuit, you get a max temp error.
if the temperature is above 15 centigrade and below the target temperature, the heater should turn on...
if the heater is on, but the temperature doesn't rise in an expected manner you will get other errors
if this happens during an active print, the error may be thermal runaway... the einsy is not seeing an increase in temperature within the time expected... so the system suspects a malfunction and fails safe... this could occur if your heater has failed, or wire broken, or drive FET is faulty so heating is not happening, or it could be that the thermistor is dislodged and heating is not being sensed to be happening
I suspect that preheat error and similar occur during the pre print time, and may have similar causes to thermal runaway. but it's never happened to me and I am not competent at reading source code to investigate...
there have been reports of heatbed thermistors becomming dislodged.... so that's probably where I would look first...especially if the at rest temperature matches the ambient temperature but warming the heatbed with an external heat source (Hair drier, or lastic mag full of hot water and tied in a knot so it doesn't leak before being put on the heatbed... doesn't result in a similar change in reported heatbed temperature
have a play, see what happens... report back...
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: Heatbed and extruder won't heat up
Hi Joan,
Yes, the temperatures are reasonable at rest and the thermistors responds well to heating with a hair dryer and when the heaters actually works. The temperatures goes up and down in a good maner with reasonable values. So I don't suspect them to be faulty.
So it must be a faulty MOSFET or similar on the EINSY board, but the only thing I don't understand is that BOTH the extruder and heatbed heating doesn't work and behaves in the same way. Could both MOSFETs' be faulty at the same time or do they interact with each other in some way if one of them are broken?
In any case I contacted Prusa again yesterday and they have now sent me a new EINSY board. I will receive it during Thursday and then try again. Hopefully that takes care of the problem.
Thanks for your suggestions.
BR
Robert
Re: Heatbed and extruder won't heat up
Hello
Here also the Heatbed AND extruder won't heat up, after replaced the extruder heater.
Temp sensors are working good (tested at 20 and heated upt to 40 degrees).
Power supply is working (2x 24V), fuese are good, and connector of Heatbed and extruder are placed correct.
Heaters are correct, there is no 24V at the connectors.
Is there something else to check, before we remove the main board. ?
Best regards Danny
Re: Heatbed and extruder won't heat up
There should be 24 volts on both input cables to the einsy. And if you test between bed+ and input- you should see 24 volts
Similarly extruder heater + to input- should show 24 volts.
With the printer switched on but at rest.
Check on the einsy connectors
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: Heatbed and extruder won't heat up
@robert-h56
Have you solved it with EINSY or what happened? I have the same problem. Thanks
RE: Heatbed and extruder won't heat up
@robert-h56
Have you solved it with EINSY or what happened? I have the same problem. Thanks
EINSY change did not help
RE: Heatbed and extruder won't heat up
Remove the connection to the "Power-Panic" unit from the Einsy board. If the heating works again then look for the fault in the PSU. Perhaps only the black and white lines are swapped.
greetings
2x Personal MK3IR-BMG09 (Full) BEAR + MMU3 mod., ...
RE: Heatbed and extruder won't heat up
@holger-s3
I had the same problem, it is an error in the connector pinning. After swapping the black and white wires, everything was ok. Have spent nearly 2 hours checking resistances, fuses, wiring, etc. without success, until I found this hint. You made my day!
RE: Heatbed and extruder won't heat up
@holger-s3
it works without PP cable, but it is not switched. White is on + and black is on - in the PSU. In the EINSY there is only one way how to connect so there should not be problem in there
RE: Heatbed and extruder won't heat up
@holger-s3
it works without PP cable, but it is not switched. White is on + and black is on - in the PSU. In the EINSY there is only one way how to connect so there should not be problem in there
so the connector PP on the PSU was switched
RE: Heatbed and extruder won't heat up
@werxx
and when did you get the new PSU?
RE: Heatbed and extruder won't heat up
@vaclav-b5
this week Tuesday, it was a new kit I ordered late March. It is the black PSU type.
RE: Heatbed and extruder won't heat up
Hello everyone,
nice that the tip with the "PP" cable helps some users.
The "PP" connection is an electrical input on the Einsy board and disables both heaters immediately, if activated. However, the thermistors continue to work. It is possible that only the white and black lines are swapped. However, a faulty "PP unit" within the PSU is also possible. If the heaters work again after removing the "PP" line on the Einsy-board, the problem will be found in the area of the PSU. The printer can also be used without the power panic function.
greetings
2x Personal MK3IR-BMG09 (Full) BEAR + MMU3 mod., ...
RE: Heatbed and extruder won't heat up
Hey, this just happened to me! 5 min before a 55hour print finished, the printer went crazy, resetting itself 3 times in a row, eventually showing 'bed preheat error'. Tested everything, turns out unplugging the b&w PP cable returns function of the heaters.D
Does anyone know why this occurs? Age, glitch, firmware?
Fair farren
RE: Heatbed and extruder won't heat up
An expected reaction in the event of dropouts in the grid-side supply voltage or low voltage. Probably not an issue with the printer.
It is best to prevent multiple short-term power failures in succession with an external protective device (UPS).
2x Personal MK3IR-BMG09 (Full) BEAR + MMU3 mod., ...
RE: Heatbed and extruder won't heat up
@holger-s3
Thanks for the info, but I do have the printer powered by a Belkin, including surge protection and battery backup. That was not the issue here, I've had the mains power fluctuate before without effecting the printer.
Maybe it's just one of those things that happen...
Fair farren
RE: Heatbed and extruder won't heat up
@kryss-e
Maybe it's just one of those things that happen...
It would have to be checked by measurements and/or simulations whether a Belkin can perform this task correctly in any case (timings and power). Accurate analysis from a distance is difficult and should be done at your location. However, there are many indications that there is an issue with the mains power in your case.
2x Personal MK3IR-BMG09 (Full) BEAR + MMU3 mod., ...
RE: Heatbed and extruder won't heat up
Thank you very much, this solved my issue.
My issue were thermal runaway errors, and the temps didnd rised at all.
My procedure, for future people stumbling over the same problem.
Measured resistance of reaters, thermistors all were OK
Checked fuses were OK
Realized that einsy board didn't activated the bed at all (No voltage output to heatbed)
Did firmware downgrades before new thermal model because its a clone build out of excess components, didn't fixed the issue.
Found this post, disconnected Power Panic, did the job.
Swapped the wiring, heating still fine.
Upgraded Firmware back to current 3.13.3 heating still works.