Dual Zone Rane CP64 Commercial Processor Humming on outputs

[Zerotolerance]

I have my first project it is a Rane CP64 PA and it hums out the speakers in both zones without any inputs plugged into it. It is a loud hum. I am assuming it has to do with the power supply portion of the board but am unsure as I am a complete noob when it comes to testing components. Any help is greatly appreciated

 

[Sceadwian]

Ground loop in the audio amp probably, that's the generic answer if you say loud him and speaker in the same sentence. How are the devices isolated?

 

[Zerotolerance]

sceadwian what does that mean lol? an open ground?

 

[Sceadwian]

Look up Ground loop.

 

[Zerotolerance]

Gentleman check out this AC sine graph. Found out the problem and repaired it

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