Guess what happened. My mainboard died. Would a mosfet have avoided this mess?
No a mosfet wouldn’t. Presumably that’s for 12v in?
However looking at the wire, a decent gauge would have been better.
That looks like my Anet A8… Is it ?
I would say yes, a mosfet to switch the heated bed power would remove that current from flowing through your mainboard. The heated bed draws a lot of current !!
@Nathan_Walkner it wasn’t. it burnt^missing/deleted image from Google+
@JP_Roy jup it is
Oh that’s a crap way of routing the power to the bed. Usually the bed terminals would melt. But yes a ssr or a mosfet would have stopped this.
I have two explanations for this.
1- the bolt has loosened.
2- the wire is too thin or has high current (A).
@Jonas_G Yeah, it’s pretty likely that a mosfet would have helped. However, like @Ricardo_Almeida said, it’s likely that a screw became loose. When they get loose, resistance increases and things get hot. It’s likely that you could just solder the wires back on and it would work.
As Johnathon stated, those 2 terminals look like they are only for the input power. They’re just too small to handle 10 amps continuous draw. I have a similar board…it runs hot too, so I installed a mini fan on top. Those boards are made with cheap components so any imperfection or flaw will cause a failure. In your case, possibly a loose or undersized connector pin.
so I would be okay if I install the exactly same board with a mosfet and a cooler?
@Jonas_G Most likely, yes. Just make sure all the screws are tight. Loose screws cause resistance to increase and that’ll cause components to get hot and melt. I use a mosfet for my bed to keep from running too much power through my board. So far I haven’t had any issues.
No, a mosfet cannot be used in an input circuit which is what those terminals are. A mosfet is an output driver transistor, typically used for controlling high current devices like motors, heaters and the like.
@Richard_Karlson the mosfet would go at the hot bed connector not on the power input. This is where the issue is.
@Jonathon_Thrumble But there already is a mosfet on the circuit board, which is driving the bed, and it is doing just fine, and it did not fail. In my opinion, it was the poor quality connector, alone, which caused the “mess” .
Of course the wording of the question leaves some doubt as to the actual question asked. He probably meant to say something like.
“Guess what happened. My mainboard died. Would an external mosfet driver board have avoided this mess?” In which case the answer would most likely be yes.
@Richard_Karlson the issue is the board is not able to cope with the 20ish amps the hot bed pulls. You would put the mosfet on the hot bed output then power directly from the power supply.