Unhappy Shruthi XT- lots of digital noise

My Shruthi XT is getting a lot of digital noise on the output. I don’t think it’s the display as it’s very loud- much louder than the normal sound itself (which also sounds distorted). It seems to come on after 2-3 seconds of being on, and is fairly continuous ie. not affected by the envelope. Changing screens or settings seems to trigger it, but it’s really hard to say. Also, the filters don’t filter the noise in any way, so maybe it’s on the ground line? IDK.

To be honest, I’m not a digital guy- any suggestions on where to start? FYI- I’m using the CS80 filter board on it.

Your help is appreciated!