Duet 3 mini 5+ fan MOSFET blown out?

Arminas

Hello,

I have been cleaning a nozzle with a wire brush and I accidentally touched the nozzle heater wires and saw a little spark. After that, my hotend fan randomly stops spinning for a couple of seconds during the print. Is it possible that after that incident, my hotend fan MOSFET is blown?

jens55

@Arminas highly unlikely. When a MOSFET blows it tends to be fatal and often involves a crater in the surface of the MOSFET package. Sometimes you even get to see the life force (smoke) leave it's little body

Arminas

@jens55 okay. Everything else seems to work fine. But maybe you have any options why does the hotend fan keeps stopping for a few secs?

Arminas

This post is deleted!

Arminas

@jens55 I have tried to swap the hotend fan and blower fan slots, nothing has changed. But can it be a broken fan if it spins while the hotend is hot (but not printing) and sometimes turns off during the printing process?

jens55

@Arminas The two things that I would suspect are intermittent power connection (bad crimp ?) or, more likely, the end of the fan's useful life. I have been able to extend the life of a fan by pulling the sticker that covers the shaft bushing and adding a drop of sewing machine oil. This is mostly an issue with sleeve bearings rather than ball bearings and especially if the fan came from China.

Arminas

@jens55 it's the default ratrig hotend fan. Ok, I will try to change it

jens55

@Arminas, fans are cheap and yes, changing the fan would be right up there in terms of trying to figure out what is going on. BTW, I have given up on sleeve bearings. Any new fans ordered are ball bearing fans. They just seem to be more reliable (for me anyway)

dc42

@Arminas said in Duet 3 mini 5+ fan MOSFET blown out?:

@jens55 I have tried to swap the hotend fan and blower fan slots, nothing has changed. But can it be a broken fan if it spins while the hotend is hot (but not printing) and sometimes turns off during the printing process?

Magnetic fields can also affect fans. Is it by any chance a delta printer using magnetic joints?

Arminas

@dc42 no, it's corexy. Looks like the wire was damaged inside the shield, it was not visible. Problem solved