Modulaire 580 Compact Disc Player (130-1252) Troubleshooting Faxback Doc. # 31777 Q: A Stereo Phono Pre-Amplifier (420-2111) was hooked up to this CD player and a hum was heard. There is no ground wire. Where can a ground wire be hooked up to eliminate the hum? A: The Pre-Amplifier (420-2111) has RCA Connectors. Try a Ground Loop Isolator (270-0054). (IR-04/02/96)