Default fault behaviour different between tool and bed?

  • Hi,

    I'm currently bench testing a board which was reported a potentially dead. From what I can see for some reason excessive current was drawn through the negative pin of the 0V-PS_ON-+5V connector through the standard Ormerod 2 external 5V regulator.

    ANy way one behaviour that confuses me is with nothing connected and both thermistor readings reporting 2000C the Tool is in fault but the Heater off? Is there anything in the config that I've got wrong here or is that default behaviour?

    Board: v0.6 (white motor plugs rather than plain 2.54mm headers.)
    Firmware: 1.22
    DWC: 1.22.4

  • administrators

    It's a while since I've used a 0.6 or 0.8.5 board, but I think the default behaviour is still that you get a negative temperature reading if the thermistor is disconnected, provided that you have configured the thermistor channel using M305. But I could be wrong, because most temperature sensor errors give a 2000C reading.

    I suspect that the reason for the excessive current draw through the 5V ground pin was that the screw in the negative VIN terminal became loose, so the current that should have flowed through that terminal block took an alternative route to the PSU.

  • My Duet 085 gave 2000C when the thermister failed open and also when there is no thermister connected.

  • Yes, that was my thoughts regarding the ground too.

    The sensors are reading 2000C with nothing connected. My confusion was why this is not shown as a fault on the heater bed but is a fault on the tool? I'll get a screenshot later.


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