Board burn out?

So, my M90 stopped working...

After the fan stopped spinning when I flip the power I got concerned, and a quick look at the Melzi board revealed the negative power cable had scorched the terminal block.
Taking the board off the frame shows rthat the underside is also damaged....

The fan did spin up a couple of times as I swapped USB cables and checked whether it was my Pi causing the problem or laptop....

/sigh

Suggestions?

Yikes! You're not the first!

How are you powering the Pi? I don't see any extra ground connections coming off the connector so did you splice it higher up the wire, or is it powered externally?

It was suspected in Terry's incident above that the increased resistance of his extra connection was what caused the overheating but that doesn't appear to be the case here.

The Pi is powered externally.
If I was going to power it off the M90 I would come direct from the PSU rather than the Melzi.

The pictures of Chargenuts connector burn look much worse, but they're the hotbed ones....
So, the solution is to replace and resolder the terminal connector? /bleh

I've been printing ABS for the last 2 weeks at 120/210...

It is simply down to the contact resistance with the wire being too high.

Perhaps it is better not to tin the wires as an excess of solder might cause it to work loose over time because it is soft. Just twist them together instead.

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[www.hydraraptor.blogspot.com]

The terminal blocks do appear to loosen over time. I have just tightened my Heated Bed terminal screws but the main power terminals were OK this time. This needs to be a regular check!

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Perhaps but I have a machine that has run longer than anybody else's and I have never needed to tighten them and they don't get even warm let alone hot. All I can think is it depends on how much solder you use or how tight it is initially. Or perhaps the shape. I trim the point so it is parallel sided and not conical where it goes into the connector so it has maximum contact area.

Edited 2 time(s). Last edit at 12/05/2013 04:12PM by nophead.

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[www.hydraraptor.blogspot.com]