Hotend Heating Failure

Hello guys,

I have recently finished building a RepRap Prusa i3 Hephestos. I printed some objects and it worked well at the beginning. However, when I printed a radial fan adapter to mount the layer fan on the E3D fan and installed it, I started getting “E1 Heating Failed” errors. Thad fan installation was the only thing that I changed, so I removed it, but that did not solve the issue. After searching possible solutions I read that it might be caused by several sources. Here are the symptoms:

• I checked the wiring of the hotend and it is OK.
• The thermistor is working because I used a hair dryer to test it.
• I measured the voltage that is being delivered to the hotend and it is 11.9V.
• Bed heating works perfectly.

When I used a multimeter to measure the voltage on the RAMPS hotend connection something weird happened, because the temperature started increasing and the printer worked well. I managed to print the radial fan adapter again using the mounted radial fan I printed at the beginning. However, when I went back to do another print right after this one finished, I started getting the same error again. Measuring with the multimeter did not magically solve the problem this time. I am not sure how to detect which component is the faulty one (MOSFET, the heating block of the hotend, …) Can someone lend me a hand?
Thank you so much

You should measure the resistance of the heating element. If it is infinite, then that component has failed.

One other way to test is to swap around the heating element wires between printhead and heated bed, and also the temperature sensor wires for the printhead and heated bed.

If the fault now effects the heated bed, and the heated bed doesn't get warm, then the fault is with the mosFET on your controller.

Rather than swap out a bad mosFET, you can alter the pin settings on firmware to use a second extruder as the first extruder. A software fix for a bad mosFET rather than changing the component.

Quote
felystar

When I used a multimeter to measure the voltage on the RAMPS hotend connection something weird happened, because the temperature started increasing and the printer worked well. I managed to print the radial fan adapter again using the mounted radial fan I printed at the beginning. However, when I went back to do another print right after this one finished, I started getting the same error again. Measuring with the multimeter did not magically solve the problem this time. I am not sure how to detect which component is the faulty one (MOSFET, the heating block of the hotend, …) Can someone lend me a hand?
Thank you so much

My guess is that when you measured the voltage, you moved something so that it was back in contact again. I'm guessing it was at the RAMPS end, since that's where you were working, and also the head moving around while printing didn't apparently break the contact again. Try (gently... you don't want to cause a new fault!) wriggling/bending the heater wires at the RAMPS end to see exactly where the fault is. Also press the MOSFET and associated components... perhaps there's a dry joint on the RAMPS board. To make it easier to detect, you could put a 12V lamp or buzzer in parallel to the heater.

Quote
DragonFire
You should measure the resistance of the heating element. If it is infinite, then that component has failed.

One other way to test is to swap around the heating element wires between printhead and heated bed, and also the temperature sensor wires for the printhead and heated bed.

If the fault now effects the heated bed, and the heated bed doesn't get warm, then the fault is with the mosFET on your controller.

Rather than swap out a bad mosFET, you can alter the pin settings on firmware to use a second extruder as the first extruder. A software fix for a bad mosFET rather than changing the component.

And when changing the heating element wires and temperature sensors should I change anything on firmware?

Edit: I have measured the resistance of the heating element using the pins on the RAMPS board and it was around 10MOhms

Edited 1 time(s). Last edit at 08/20/2021 06:13AM by felystar.

I can no longer edit my previous post, so I’ll make a new one.

I tried to heat the hotend one last time before changing the cables as DragonFire suggested. And to my surprise it worked. I have managed to get some prints done without getting heating issues. It seems like it is kind of random, or maybe some component is about to die. Will keep testing.

Edited 1 time(s). Last edit at 08/21/2021 07:42AM by felystar.

Intermittent connection of the heater for the hotend.

10 Megaohm is like no connection at all, resistance should be for 20 Watt heater cartridge and 12 Volt supply, 7.2 ohms.

Cartridges are cheap to replace, but make sure it isn't a problem with the connector where it attaches to the controller board.