Possible to add failsafe to SSR?

I bought a GeckoTek magnetic base and plate system after I chipped yet another glass bed. (Thank you Polymax PLA)

The GeckoTek system has a much better heater built in, and GeckoTek warns that the RoBo's stock power supply wont heat it reliably above 75C. They were looking into offering a 24V upgrade kit, but that appears stalled out for now.

I was looking into adding an SSR with a 24V supply, but with all the fake SSRs out there (even the Fotek's with the notched label saying Taiwan Made are suspect now). My concern is that SSRs tend to fail closed, pumping more and more heat into the bed until *poof* or worse.

Does anyone know a way to add something in Marlin to trigger a spare pin when Marlin triggers on a thermal runaway? (bed_max_temp_error()) I can tie that trigger into a relay to kill power to the power supply.

 

I added an SSR and although I've had no issues I agree the safety of the heated bed in general could be improved. Perhaps a fuse, possibly thermal fuse would be even a better solution? That way you're not relying on software to shut things down.


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