Heated Bed makes my lab power supply hum

nikscha

Hey there,
I have a 900W mains heated bed, driven by a SSR, configured like this:

;Bed:
M308 S0 P"bedtemp" Y"thermistor" T100000 B4066        ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0                                 ; create bed heater output on bedheat and map it to sensor 0
M143 H0 S130                                          ; set temperature limit for heater 0 to 130C
M307 H0 A120.4 C698.3 D2.0 S0.7 V24.4 B0              ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0                                               ; map heated bed to heater 0

If the heated bed is running and my Lab power supply is on, the supply makes a humming noise at the same time the SSR is driven.
I belive that the humming is related to the PWM frequency that the SSR is driven at.
The supply hums regardless of whether the bed is in PID mode or bang bang mode.

Any ideas?

DIY-O-Sphere

@nikscha
Reduce the frequence for the ssr. (Q parameter for heater) I had the same problem.

Edit:
That is my setting
M950 H0 C"bedheat" T0 Q10

nikscha

@DIY-O-Sphere Solved! Many thanks