UM2+ switches off when heating buildplate

[WindyMiller 2]

I noticed this problem when I tried to do a print and the printer switched off after a second or two and then rebooted.

 

I did a few basic tests and found that it can heat the nozzle but not the bedplate.  As soon as I try to heat the bedplate it switches off then reboots.

 

Based on previous threads for similar problems it seems like it might be the power adaptor that's letting me down.  The printer is four years old and the adaptor is model GST220A24-R7B.

 

Any assistance much appreciated, either confirming the likely power adaptor problem or suggesting alternatives...

 

Thanks!

[Dim3nsioneer 557]

This can be the PSU or a slight short in the print bed or the heater cartridge.

Best measure the resistance of the latter two. The bed should be something like 3.5 ohms iIrc.