dbx 131 noise issues?

[MustangMan78]

I picked up a used dbx 131 to use as a HPF/LPF and tweak my tone. This thing is SUPER noisey. As soon as my gate opens, there’s a ton of noise and hiss. I bypassed the unit (as in removed from the signal chain) and…silence. I have the 12db slope button pushed and the gain dial at 0. I’m cutting full from 40Hz down and above 4000Hz. Everything else is neutral (for now). I think the unit is defective. Thoughts?

 

[jdaunt]

I had a 231 and had the same issue. Never figured out how to get rid of the hiss other than get rid of the unit-which i eventually did.