Bed Thermistor reading keeps rising but the bed stays cold.

  • Hello everyone

    I bought a Duet WIFI in October of last year, but never got around to actually using it, because a lot of things got in the way. Now that i have more time, i finished the Printer build (P3Steel Toolson mk2) and wired most of it up to the Duet to test things.

    The Problem:
    -The Bed thermistor reading just keeps rising as soon as i turn the Printer on.
    -The actual Temperature doesnt rise at all, it stays cold. It only heats up when i tell it to go over the temperature its currently "reading", so Heating would work.
    -The Temperatureading rises very quickly up to about 90°C and slows down until it just goes up by 0.1°C every 10 seconds or so after about 126°C (The bed is still cold though)
    -Same Problem without anything connected
    -Same Problem with Hotend Thermistor connected
    -Same Problem when connected with a jumper

    Information about the Printer:
    -Duet Wifi, bought 19/10/2016
    -800W 24V Power Supply
    -200W Silicone Heater with a "100k Thermistor" (FilaFarm FilaBase)
    -E3D V6 24V
    -5V Radial Print cooling Fans connected + to 5v and - to Fan0 gnd
    -24V Hotend fan connected to Fan1

    Temperature settings in config.g:
    ; Heaters
    M143 S300 ; Set maximum heater temperature to 300C
    M305 P0 T100000 B4725 C0 R4700 ; Set thermistor + ADC parameters for heater 0
    M305 P1 T100000 B3950 C0 R4700 ; Set thermistor + ADC parameters for heater 1

    Firmware Version: 1.19.2 (2017-09-01)
    WiFi Server Version: 1.19.2
    Web Interface Version: 1.19

    Edit: I assigned the bed thermistor to E1 Thermistor for now, so i can test the bed and hotend together. Everything works just fine so i guess there is a problem with the bed thermistor input. This works but i would still like to know whats wrong so i can avoid doing it again.

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