@mendenmh Hi, thanks for your input, it was the "setting the bed heater to Bang Bang" suggestion that worked. cheers

@T3P3Tony Thanks that done the trick. Could you explain why? many thanks Jim

Has anyone got an idea as to what is going on please?

Unable to measure at the Power adapter terminals because it uses a R7B connector but at the VIN terminals it was 24.2 volts with the heater off and 23.83 volts with the heater on continuously. One thing I did notice was that the lighting LEDs flickered and the power adapter buzzed together when the temp reached 50°C. Also, because I had the printer on it's side, I could see that there was a red LED flickering next to the VIN to Bed fuse.

@dc42 could you suggest an external mosfet that’d work well with my board or they all pretty much the same? Thanks

I've just taken it to 600 and it still buzzes. The flickering stopped though so that's a start. Think I'll just keep the LED's turned off

Does the board use more power than the original Ultimaker board because that's all I have changed?

@Phaedrux Tried what you suggested for the PWM frequency and the PSU started buzzing, is this right?

Do you have any recommendations on a better PSU? I'm using the meanwell GST220A24-R7B power adapter that came with the Ultimaker 2+. Thanks

hi, I'm using version 2.05.01 firmware