Technical Assistance !

I just purchased a used Roland Super Cube SCL-60...cleaning the spider webs out of the rear cabinet I noticed the green ground wire is off.

Can anyone tell me if this wire is necessary ? if yes, where I should attach it to??

Any answers would be appreciated !

is it the ground wire coming from the power cord?

If so it should go to a chassis ground, either to a transformer lug or to screw bolted down securely to the metal

its a separate wire...not attached to power cord. One end was attached to metal panel, so other goes to transformer lug then?

Maybe post some photos of it..