SKR 1.4 using Replicator 2x heated bed makes high pitched noise

Hi all,

I'm facing an issue of which I do not have sufficient knowledge. The SKR1.4 is driving the old Replicator wonderfully but when the bed is heating, there's a high pitched sound coming from the electronics board.
#define MAX_BED_POWER 255 // limits duty cycle to bed; 255=full current in Marlin. I am afraid to lower it because I understand this will put strain on the MOSFET.

Should I check the bed's resistance? I did and it is 4,7Ohms Should I build a circuit with a power mosfet to drive the bed power? Should I limit the current through the firmware? (Marlin).

It's a 24v system. I've never heard this noise and don't know if it's good or not.

Update:
I did some more research and found this:
[github.com]

It says:


According to this website:
[ohmslawcalculator.com]

A heated bed with 24v and 4,7Ohms of resistance should pull this:


So, if the SKR 1.4 can deliver 144W to a bed with higher than 1Ohm resistance, and according to the formula my bed pulls 122W and has 4,7Ohms, that should be safe right?

So, I'm wondering, where could the high-pitched wine be coming from? And is there maybe a way to limit the current draw of the bed through Marlin by using a lower PWM signal or some tech?

Edited 4 time(s). Last edit at 07/31/2020 05:54PM by Ohmarinus.

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I've added some updates. No takers?

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