I'm trying to connect an older (1995) Sony CDX-51RF 10 disc changer to a brand new Kenwood head unit in my car. The Sony changer normally uses an FM transmitter hooked to the antenna cord, and sound from the Sony disc changer is provided to the FM transmitter via left and right RCA cables. The transmitter is grounded to a console metal member. The Kenwood head unit is grounded through the OEM stereo wiring harness. I want to connect the disc changer RCA outputs directly to the Kenwood head unit so that I'll get better sound. Power and control for the disc changer would still be provided by the original CD changer control and FM transmitter/control box. In other words, nothing is changing except for where the disc changer RCA output terminals are connected.
When I plug the disc changer RCA outputs into the Kenwood head unit RCA aux. inputs, the signal is extremely distorted, as if it's being overdriven or as if the incoming signal from the CD player is too strong. The distortion occurs at any volume level. This isn't a hum or a buzz. Rather, the audio is just extremely distorted, kind of like turning the stereo all the way up on a cheap set of speaker. However, when I back the RCA connector out so that only the center plug is touching (i.e. the outer conductor is not touching & not grounding), it produces a more normal signal, albeit with a little bit of noise.
Does this indicate that the Sony disc changer has an amplifier in it and is providing too much power to the Kenwood stereo? Or, does it indicate that I have some sort of grounding problem? Do you have any suggestions or equipment for solving this problem?
How might I measure the output of the Sony disc changer on the RCA cables to determine if it is an amplified signal or if it is a standard "line out" signal that can be handled by the Kenwood head unit?
Incidentally, when I plug an MP3 player into the Kenwood head unit RCA aux. inputs, the sound is just fine, so the problem is definitely something peculiar with the signal coming from the Sony disc changer.
Thank you for your help!
