Confused over bed heater tuning

  • Hi Everyone,

    I think I have managed to confuse myself over my bed heater. I thought it wasn't heating up as fast as it used to and that maybe i changed a setting or something is wrong. Having checked all the wiring I'm pretty sure I was just imagining an issue that doesn't;t exist. In the process, I have gone round and round on what I need to do in the config for the bed.

    I have a 220v silicone bed via an SSR and this is what config i have

    M305 P0 T100000 B3950 C0 R4700
    M143 H0 S120

    I reset my config-override and did a tune but that put it into PWM mode. Which I understand is just pointless when running an SSR.

    So my questions are. Am I missing something from my config to force bang-bang (or leave it implied) and do i need to run an autotune?

  • Autotune, yes. On my SSR controlled heaters, I DO run PWM, via the B0 here:

    M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit

  • Moderator

    Bang bang is not recommended for bed heater in quite some time. It’s likely a zero crossing ssr (I think that’s the right term) so there should be no issues with pwn.

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