Heatbed won't shut off?
Hey guys,
I tried googling around and everything comes back trying to troubleshoot the opposite problem.
Maybe my google-fu is getting worse as I get older.
Anyhow, we just got done installing the Mk 2.5 upgrade kit with a new hotend, the wizard says we're good to go and our first couple prints have come out very nicely on the new print bed, but there's one troubling symptom: The heat bed won't cool down. In fact, it appears the printer is actively keeping the heat bed around 117 C, even after instructed to "cooldown" from the preheat menu.
Any advice? Our workaround has thus far been to just turn the printer off, but it seems really weird for the bed to *always* be this hot. It even stays around 117 when our gcode specifies 85 C for our PETG print.
Re: Heatbed won't shut off?
Had same problem with one RAMPS board: the heatbed mosfet that had shorted, it was always on... so check the fet on the board. It it has blown, there's usually some physical damage on the chip.
For me there wasn't any doubt, I saw the operating smoke that came out of the fet 🙂
Re: Heatbed won't shut off?
Well that would explain the odor. I'll have to disassemble the thing and give the RAMBO a good inspection. Hopefully I have those FET in stock so I don't have to order parts.
Thanks for the answer!
Re: Heatbed won't shut off?
It's pretty clear that MOSFET is blown to kingdom come. I hope the pads are still solder-able. The part is relatively inexpensive but it looks like it's hard to get ahold of.
Thanks for the information. Turns out a blown FET was exactly the right answer.