Problems with thermistor on dual zone heated bed

  • Hello everyone,

    with the help of this thread Using Multiple Bed Heaters I have set up my dual zone heated bed. I'm using 2 AC heaters controlled via 2 SSR's.

    The heater on heated bed output (H0) is working well, but when heating the E3 (H4) I get "Error: Heating fault on heater 4, temperature rising much more slowly than the expected 1.8°C/sec". When connecting the heater to H0 it's getting warm, also when I connect the thermistor to the H0 thermistor input I see that it's registering a rising temperature well faster than the 1.8°C/sec.

    So my guess is that the H4 heater doesn't get the thermistor signal??

    ; ============= Bed Heaters =============
    M140 P0 H0
    M140 P1 H4
    M305 P0 R4700 T100000 B3950
    M305 P4 R4700 T100000 B3950
    M143 H0 S120
    M143 H4 S120
    M570 H0 S1000
    M570 H4 S1000

    I really hope there is no silly mistake I made 🙂

  • administrators

    Have you tuned heater 4, or set the M307 heater model parameters some other way? The default model for heater 0 has the parameters of a typical bed heater, but the default model for all other heaters has parameters typical of an extruder heater. So if you haven't set the model parameters of heater 4 with a M307 command, the firmware will expect it to behave like an extruder heater; but bed heaters typically heat up much more slowly.

  • Well, that was simple. Thank you.

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