Shorted E0 heater block



  • Hello,
    I was trouble shooting an issue with my heater block not warming up. Turns out i just had a bad crimp creating an open circuit but while I was troubleshooting I accidentally shorted the E0 heat block terminals and blew the 7.5A fuse. My board is the latest revision of the Duet 2 wifi. Looking at the datasheet for the AOD4184A MOSFET it looks like it can handle a 50A current so I suspect it is fine (I am getting a new fuse soon so I'll find out) but I am wondering if this could cause any other components other than the E0 heater mosfet to be damaged potentially. Thanks!
    -Nick

    Edit: I took out the 15A fuse for the bed and put it in place of the 7.5A fuse just to test things. The E0 terminal (and everything else) is working correctly so it seems no damage was done but still wondering if I may have reduced the life of any components. Thanks



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  • @NickL1996 said in Shorted E0 heater block:

    could cause any other components other than the E0 heater mosfet to be damaged potentially.

    if you only shorted the heater output to ground then you got lucky if the mosfet survived, 50A is "nothing" compared to a short circuit current for a dead short.

    (the common fault where other parts get damaged is when you short just the positive heater output to heater block along with fans or thermistors effetively shorting Vin to other parts of the board)



  • hmm well I was trying to measure the voltage with my multimeter probes on the flathead screws of the terminal for e0. I thought the probes were not touching since they are small and pointed and each screw terminal is separated but I heard a spark and then the fuse was blown. Maybe the connection making the short had a small enough surface area to limit the current below what would destroy the mosfet? I see no damage to the mosfet or traces and the board is working with a new fuse so is it safe to say I got lucky and no damage was done?



  • @NickL1996 said in Shorted E0 heater block:

    Maybe the connection making the short had a small enough surface area to limit the current below what would destroy the mosfet?

    more likely the power supply has short circuit protection; in either cause impossible to say weather or not the mosfet will have a long and happy life post incident as there is no way of knowing how much current passed through it for how long - but its possible (it'll be fine).

    best bet is to chalk it up to a win for now and deal with replacing the mosfet if and when it fails.



  • To be safe I switched the heater to E1 since this is a delta printer and I wont be installing a dual nozzle system. Thanks for the insight!


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