Passive ABY switcher noisy ground hum and no signal when ground lift is switched.

[Zmorris90]

Hi all, I recently finished the new ABY switch and I’m having issues with the ground lift. So I have relocated the ground switch to a spst toggle on the surface so it would be accessible without opening the enclosure. My issue, when I engage the ground lift a terrible 60 cycle hum comes thru the B side and no signal behind it. The only thing I don’t have on the build is the keystone 628 ground spring. I do have a cliff-jack ground ring on the input of the switcher since I had a few on hand. I have attached photos below, Any suggestions would be appreciated! Thanks!!

 

[Robert]

The only thing I don’t have on the build is the keystone 628 ground spring. I do have a cliff-jack ground ring on the input of the switcher since I had a few on hand.

You only need one or the other, both aren't necessary.

The ground lift is a passive ground lift, it depends on output B having an alternate external path to ground (hence the need for a ground lift).

What does your signal path look like? If you're getting 60hz hum with the ground lift engaged it's likely output B is isolated and the lift isn't necessary.