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Thermistor wonky when N / L are switched
So my heatbed thermistor (orange) showed weird fluctuations, sometimes random, sometimes very regular.
After a lot of troubleshooting, I noticed it went away when the 230V lines of the heater are not connected. Reconnecting them: wonky again.
I checked all cabling (no change) and then had the idea to switch the plug of the printer around (so switching neutral and live), and now its gone as you can see on the second picture.
So its fixed, but any ideas what was causing those fluctuations? Is that maybe an indication of a bad SSR or something?
Edit: Its still fluctuating, but a lot less.
Additional Infos:
- Thermistor showed same behavior on a different TH-port, while another thermistor on the normal bed port was fine.
- In the first picture the heatbed was off for an extended period, so no power should have been flowing through the bed
Fix: Set your heater pwm to anything but a multiple of 50 Hz. For example:
After a lot of troubleshooting, I noticed it went away when the 230V lines of the heater are not connected. Reconnecting them: wonky again.
I checked all cabling (no change) and then had the idea to switch the plug of the printer around (so switching neutral and live), and now its gone as you can see on the second picture.
Edit: Its still fluctuating, but a lot less.
Additional Infos:
- Thermistor showed same behavior on a different TH-port, while another thermistor on the normal bed port was fine.
- In the first picture the heatbed was off for an extended period, so no power should have been flowing through the bed
edit: Fixed:
See the summary of this post: Thermistor wonky when N / L are switchedFix: Set your heater pwm to anything but a multiple of 50 Hz. For example:
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