Possible short in pt100? Sparking hotend



  • Im running my duet wifi on a ultimaker 2 clone... it uses an ultimaker 2 hotend with olsson block and pt100 sensor...

    Whenever i touch any metal on the hotend carriage, it makes sparks from inside the hotend/carriage somewhewhere.. either heater, pt100 or cooling fan...

    Its very on off... it mever happens when printing... only when touched by some metal, scewdriver etc...
    If i touch the hotend and the case on the printer or my pc case, i get constant shock..

    Whenever this happens, temp goes to 2000c and goes back normal as soon as nothing is touching it...

    NO wires of any kind is touching the metal... neither are the wires damaged or possible to touch eachother and short...

    I believe it is either the heater or pt100, which is both original ultimaker 2..
    Pt100 has been made from 2 to 4 wires..

    I cant provoke this by messin around with cables... only by touching the metal shielding.....

    It heats and reads temperature fine...


  • administrators

    @johnjohn1990 said in Possible short in pt100? Sparking hotend:

    Whenever i touch any metal on the hotend carriage, it makes sparks from inside the hotend/carriage somewhewhere.. either heater, pt100 or cooling fan...

    Touch it with what? A ground wire, your finger, or something else?

    If i touch the hotend and the case on the printer or my pc case, i get constant shock..

    That sounds like leakage through the PSU, and leakage or a short between either the PT100 element or the heater element and the hot end metalwork, and absence of a connection between the negative output of the PSU and ground. I suggest you:

    1. Add that connection - but if you are using the Duet's USB port, beware of USB ground loops (see the wiki page on that subject).
    2. Use a multimeter to check for shorts or leakage between the PT100 or heaters wires and the hot end metalwork.


  • disconnect the printer and check that the power supply grounding is working first. there are cheap power supplies where the ground is not connected properly.

    then use the multimeter to check the voltage between hotend and case.
    then remove one thing after another(heater,pt100,sensors etc) to find out which is causing that occurrence.



  • Now im asking stupid... how do i check for shortage in pt100 and heater? That stuff isnt really my primary doing..

    Its uses a brand new 24v meanwell 32a psu..
    Its not grounded on 220v side, since i dont have any 3pin plugs in my wall..
    I dont use usb at all 🙂



  • @veti said in Possible short in pt100? Sparking hotend:

    disconnect the printer and check that the power supply grounding is working first. there are cheap power supplies where the ground is not connected properly.

    then use the multimeter to check the voltage between hotend and case.
    then remove one thing after another(heater,pt100,sensors etc) to find out which is causing that occurrence.

    Ofc!

    Maybe that schock blew my mind out too.. sometimes i should think a little more before asking....

    Thank you.. will get right to it


  • administrators

    @johnjohn1990 said in Possible short in pt100? Sparking hotend:

    Now im asking stupid... how do i check for shortage in pt100 and heater? That stuff isnt really my primary doing..

    Disconnect tghe PT100 wires from the daughter board, then use a multimeter to measure the resistance between one of the PT100 wires and the hot end metalwork. Your multimeter should report it as "infinite".

    Check between one of the heater wires and the jot end metal work in the same way.

    Its not grounded on 220v side, since i dont have any 3pin plugs in my wall..

    Ouch! Is that legal in your country? Here in the UK, anything with a metal case (such as the case of the Meanwell) must be powered using a 3-core mains cable and plug. There is no such thing as a 2-pin wall socket, except for a shaver socket that has a built-in isolating transformer.



  • @dc42 said in Possible short in pt100? Sparking hotend:

    @johnjohn1990 said in Possible short in pt100? Sparking hotend:

    Now im asking stupid... how do i check for shortage in pt100 and heater? That stuff isnt really my primary doing..

    Disconnect tghe PT100 wires from the daughter board, then use a multimeter to measure the resistance between one of the PT100 wires and the hot end metalwork. Your multimeter should report it as "infinite".

    Check between one of the heater wires and the jot end metal work in the same way.

    Its not grounded on 220v side, since i dont have any 3pin plugs in my wall..

    Ouch! Is that legal in your country? Here in the UK, anything with a metal case (such as the case of the Meanwell) must be powered using a 3-core mains cable and plug. There is no such thing as a 2-pin wall socket, except for a shaver socket that has a built-in isolating transformer.

    Legal and legal... depends..
    If the electrical installations in the property is older than before the law you mention, its only related to if youre running a business, and insurance coverage if something catches fire...
    Ive never heard otherwise... 🙂

    It just says "1"... as it shows if i dont connect it to anything.. so i believe that is ok?
    Tried all 4 wires, all fans and heater, nothing...

    Also i cant measure any voltage between hotend/carriage and case/frame... nothing..

    This still happens when i take heater and fans completely off.. so right now its only the pt100 connected to the board, and it still does it... this my 4th pt100 sensor in half a year 😮


 

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