If the cheater plug works try the HUM-X device. It goes between the AC plug and outlet and lifts the ground connection by using two diodes wired in parallel in opposite directions. This breaks the low level signal loop but allows current through if you have a short on the chassis.
Yes, they really work. You could easily make one yourself if you wanted to. They are kind of expensive for what they are but they work.
Yes, they really work. You could easily make one yourself if you wanted to. They are kind of expensive for what they are but they work.