Trouble with DUET 0.8.5. died?



  • Hello All !

    My duet worked fine for a long time.
    But recently something has trouble in electronics and now the temperatures are not right.
    CPU temp show -274.9 degrees and heater and bed show wrong temps.
    Tried to disconnect everything from the board, powered by USB and nothing changes.

    0_1529136801668_duet085.png


  • administrators

    That sounds like an issue with the ADC. Shorts between the thermistor and heater wiring can cause that on the Duet 085. Also check whether component L7 looks intact - it's a small black component close to the processor.



  • @dc42 said in Trouble with DUET 0.8.5. died?:

    That sounds like an issue with the ADC. Shorts between the thermistor and heater wiring can cause that on the Duet 085. Also check whether component L7 looks intact - it's a small black component close to the processor.

    L7 looks like ok, but i check it with multimeter and it shows 20 ohm. it's wrong ?


  • administrators

    It should be less than 1 ohm. Check what your multimeter reads when you short the leads together.



  • @dc42

    @avaradus said in Trouble with DUET 0.8.5. died?:

    @dc42 said in Trouble with DUET 0.8.5. died?:

    That sounds like an issue with the ADC. Shorts between the thermistor and heater wiring can cause that on the Duet 085. Also check whether component L7 looks intact - it's a small black component close to the processor.

    L7 looks like ok, but i check it with multimeter and it shows 20 ohm. it's wrong ?

    @dc42 said in Trouble with DUET 0.8.5. died?:

    It should be less than 1 ohm. Check what your multimeter reads when you short the leads together.

    Wires of multimeter has 2 ohm and with L7 shows 22 ohm.
    And if i short E0 temp duet then shows 3090 degrees
    If short bed temp then duet shows 7841 degrees
    May be processor is overheat ? it's very hot !


  • administrators

    It sounds to me that the processor has been damaged. The symptoms you describe (overheating processor and L7 failed) suggest there was a short between the VSSA side of a thermistor connection, and a heater or fan wire. I've heard of this happening a number of times on Duet 06 and 085 boards. That's why we added protection to the VSSA line on the Duet WiFi/Ethernet.


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