Burnt out heat bed?
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I went to start a print and noticed the bed wasn't heating up. Upon further inspection I noticed that the terminal on the board is actually burnt. What happened? How do I fix it?
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Were you using crimped ferrules on the bed wires?
You may be able to replace the terminal if no other damage has been done to the board or surrounding components.
https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers#Section_Screw_Terminals
It is recommended to use bootlace ferrules for power and bed wiring. Loose wires, or tinned wires, have a tendency to creep over time and cause a loose connection. This in turn increases the resistance and heat generation and even arcing.
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I was using the bootlace ferrules. That's why I don't understand how it happened? Shouldn't the fuse have blown first?
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That looks like tinned wires to me?
The fuse holder is empty. I assume you've removed it to check it?
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@AlexTheGreat
under the board the blue cable is this damaged?
and it looks like it was also burned under the board.
So maybe a short with the damaged cable under the board? -
@Phaedrux It's whatever wires the ender 3 uses aha
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@danym21 No. I pulled out a new bed and hooked it up and it seems to be working alright still. No idea what caused it to happen though.
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@AlexTheGreat
so all working again?
is this your heatbed cables?:
please use crimped cables and not tinned wires.
tinned cables become soft and then you lose pressure on the connection, this will heat the connection regarding the higher resistor under load
please cut the tinned part of and use crimped connection like this cable:
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@danym21 Yeah that's the new ones before I crimped them and put them in. Everything seems to be working again for the time being. Would be nice to know what caused it though.
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You can't crimp tinned wires.
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@Phaedrux I mean you can. It's just not good practice. But I did cut and crimp them, didn't crimp over the tin.
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FYI, If you want to avoid high currents on the duet board or it's green terminals, you can use an external DC SSR or power MOSFET.
You can find some information here https://duet3d.dozuki.com/Wiki/Choosing_a_bed_heater
