Have some pity.

Runklestiltskin

Today I came to my printer (Duet 2 Wifi controlled) and it had it's Bowden-Tube popped out.

Trying to start the print again after poking the nozzle, made me realise the hotend fan was not spinning.
I tried another fan directly plugged in to the board and it didn't spin, either.
So I figured (BIG MISTAKE) pop in my experimental board and try this one.
Plugged everything in, tried the before mentioned fan, everything was working.
I switched to the hotend fan (BIG MISTAKE) and switched the machine on and I heard a sparking sound.

TL:DR I had a bad fan kill two of my boards,
I want protection against something like that in the future.

Thanks and press 'F' for two dead loved ones.

appjaws

Do your other fan connections still work?
I thought you said that the fan did work in another connection, so is the fan faulty or was it connected incorrectly?
If you have a good fan and the other fan connections still work you can assign another fan output for your hotend fan.
Which firmware are you using?

A Former User

Pitty won't help to be honest, but maybe you can try to figure out what caused the problem and see if there is hope for getting the boards fixed

Odds are something shorted on your hotend to cause a cascading failure? Pictures, accurate description etc.

dc42

@Runklestiltskin, I'm sorry to hear of your misfortune. Except on early Duet WiFi boards, the fan circuit is protected by a 1A blade fuse. Unfortunately, the fuse is not fast enough to protect the fan mosfet from a shorted fan (or in some cases a fan with the + and - wires swapped), however it will protect the PCB. So if the problem was a shorted fan or a fan with the + and - wires swapped, the only casualties should be the mosfet that drives the fan output that it was connected to, and perhaps the fuse as well. The fan mosfets can be replaced (and of course so can the fuse).

A Former User

This is a good a starting point to find out what the status of the boards are, go through step by step noting what the results are. Probably easier for the rest to follow the thread if you deal with one board at the time?

https://duet3d.dozuki.com/Wiki/What_to_do_if_your_Duet_won't_respond

Runklestiltskin

@dc42 Thanks for the reply. Is there more information on the repair part (changing the mosfet, not the fuse, this exchange I am able to perform). Is there an e3d repair service for these cases?

A Former User

Step 1. Identify the fault.

Then plan the repair. Although for the hotend mosfet put "smd rework sot23" into youtube and you'll probably get some examples of how its done. part numbers are on the schematics.

Runklestiltskin

@appjaws I have an Anycubic Predator here it uses a combined positive wire for both part cooling and hot end fan and it uses separate negative wires, so "furtuanitly"/s two of my three ports have been fried. My guess, since it happened midprint is, that the hotend fan is shorted. Thanks

dc42

If it was a fan internally shorted, it would only have blown one mosfet. So if more than one fan output isn't working, either the fuse blew as well or it was some other type of fault.

Runklestiltskin

@dc42 said in Have some pity.:

e than one fan output isn't working, either the fuse ble

Thanks man.