HE280 heater decoupled [SOLVED]

[noname117]

Followed the guide on installing a HE280 hot end on a Rostock Max v2 however, when I first turned it on before installing the firmware, the hot end randomly heated up to somewhere around 200 C. While I thought this was odd, the heater turned off after reaching around 200 C and so I continued with installing the firmware and calibration. However, whenever I attempt to heat the hot end up in any way, the temperature doesn't change and the screen will throw a double "def" error on the temperature readings with the message "heater decoupled" a few seconds after the command is sent. At idle the thermistors both read around 25 C so I know the def error isn't related to them being too cold. I am also able to heat the bed up independently of the hot end without issue.

Solution: As one of the commenters suggested below, the issue was a blown fuse on the HE280 hot end. I replaced the fuse and it is working fine. I still do not know what caused the hot end to randomly heat up and blow the fuse when I first turned it on but it hasn't happened again.

[geneb]

I bet you blew the thermal fuse and will need to replace it.

g.

[noname117]

I bet you blew the thermal fuse and will need to replace it.

g.

Scratch what I wrote earlier

You are right the Thermal Safety Fuse on the hot end is busted. I assume it happened when the hot end randomly heated up when I first powered on the machine. I guess the question now is why that happened.

[geneb]

You probably had a short somewhere. I've never heard of an actual instance of uncommanded heating ever happening on a RAMBo before.

g.

[noname117]

Would a short somewhere on the PCB of the HE280 cause this? All the soldering i did on it looked good but i am not the worlds greatest with a soldering iron. I'm trying to find the problem before i blow another fuse.

Also would there be any issue with using a little hotter fuse there such as a 120 C fuse rather than the 98 C? I ask mostly because i can get cheaper fuses and faster shipping from amazon but the lowest temp i can find is 120 C.

[geneb]

Don't change the fuse type. You may simply have it wired incorrectly - make sure the whip connector wiring follows the diagram in the docs.

g.

[noname117]

Ordered several more fuses in case I blow another one. Will update this post when they arrive. Thanks for your help

[Ravitch]

If you tightened the washer down to hard or with the weak little arms outside of the track you could have caused a short like I did where the thermistor wire was touching the hot end.

Side note, you can solder up a car fuse to your blown fuse. That's what I did while waiting the 2 weeks for a replacement to come from China.