Weird heatbed thermal runaway with some melty connectors
Greetings!
This morning I was greeted by:
and some plastic smell..
Following that, I quickly disconnected the PSU cables:
Then the same cables from the inside, extruder one looked healthy, the bed one on the other hand:
I took out the RAMBO to see what's up inside and was greeted by some weird stuff:
As you can see the inputs of the PSU are whitened, overheated, fragile. One pin on the top is almost molten off completely..
The bottom row of connectors also have one heatbed pin quite twisted and charred..
The 15A fuse surprisingly, even though browned from heat, still functional and shows continuity using a multimeter..
OctoPrint shows how it happened:
I am wondering, what could have caused it?
Maybe the bed cables somehow shorted? I am using the MK2.5 new "cloth" cable, that doesn't have nylon filament in it anymore so it feels kind of floppy.. Too floppy for constant movement..
Or was it connectors having HUGE resistance and eventually giving up?
This printer is not young, mind you. 2 years old or even older..
My steps of fixing will be:
Replacing the sockets for the connectors
Replacing the connectors on each and every cable and cleaning ferrules
What other precaution options you'd recommend me?
Re: Weird heatbed thermal runaway with some melty connectors
We removed the sockets at my workplace, the pad underneath seems to be toasty...
Re: Weird heatbed thermal runaway with some melty connectors
Guess I will see if it still works in the evening..
Re: Weird heatbed thermal runaway with some melty connectors
After replacing some more stuff and connecting everything back up the printer is alive again.
Lesson learned: take care of your connectors and replace them if your printer is old.
Re: Weird heatbed thermal runaway with some melty connectors
I've soldered XT90 connectors to the board after this happened twice. This on-board connectors require a perfect fit. If they are under slightly angle (which happens because of the movement), you will get a burned connector over time.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Weird heatbed thermal runaway with some melty connectors
I've soldered XT90 connectors to the board after this happened twice. This on-board connectors require a perfect fit. If they are under slightly angle (which happens because of the movement), you will get a burned connector over time.
How did you make them fit? I'd say soldering XT60 would be enough or even xt30 to keep original placements..
My printer is now completely heating up for PETG (255'C/90'C) in 4 minutes, so I guess that's the main indicator to keep track about connector well being.
Before it was taking up to 10 minutes.. after that eventually burning up and locking up.. 😀
Re: Weird heatbed thermal runaway with some melty connectors
How did you make them fit? I'd say soldering XT60 would be enough or even xt30 to keep original placements..
Sure, good XT60 would do the job as-well. I soldered cables to the backside of the board and cables to the connector. So the connectors are at the bottom of the case, easy to access. It's also helpful to use external power supply (outside the box).
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Weird heatbed thermal runaway with some melty connectors
How did you make them fit? I'd say soldering XT60 would be enough or even xt30 to keep original placements..
Sure, good XT60 would do the job as-well. I soldered cables to the backside of the board and cables to the connector. So the connectors are at the bottom of the case, easy to access. It's also helpful to use external power supply (outside the box).
My PSU is already outside of my enclosure, I made the PSU cables longer to avoid any pulling yesterday. I will see how the new connectors hold up, if the old ones survived 2+ years, I think these will survive just as long or I will just plop some XT60/XT30 on the board like you did.
Re: Weird heatbed thermal runaway with some melty connectors
My PSU is already outside of my enclosure, I made the PSU cables longer to avoid any pulling yesterday. I will see how the new connectors hold up, if the old ones survived 2+ years, I think these will survive just as long or I will just plop some XT60/XT30 on the board like you did.
The connector itself is not an issue. The problem is the angled placement. The cables are being bend by the case door. You might stay lucky if it stays in plays but once you open the door again, the placement might change and the cables will push the connector out of angle over time.
Because you did everything new, I would also try it first with the current setup. I've redone this also only after second time 🙂
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
Re: Weird heatbed thermal runaway with some melty connectors
My PSU is already outside of my enclosure, I made the PSU cables longer to avoid any pulling yesterday. I will see how the new connectors hold up, if the old ones survived 2+ years, I think these will survive just as long or I will just plop some XT60/XT30 on the board like you did.
The connector itself is not an issue. The problem is the angled placement. The cables are being bend by the case door. You might stay lucky if it stays in plays but once you open the door again, the placement might change and the cables will push the connector out of angle over time.
Because you did everything new, I would also try it first with the current setup. I've redone this also only after second time 🙂
I've actually added super flexible cable extensions to PSU connector and made it 4x1 instead of two 2x1 connectors so I guess it will stay more sturdy.. 🙂