I have searched the forum and seen this problem asked before, but no one has provided a confirmed solution.
My Xenarc 700YV has a noise issue (faint horizontal scrolling lines) via the composite input when powered via direct DC. I have tried a regulator circuit to make sure voltage fluctuations were not the cause, as well as a ferrite bead, and an RCA signal filter. The problem does not exist when i use the AC/DC power adapter connected to my power inverter.
No one has addressed why the display is clear using the inverter. Will a specific type (certain mH inductor, frequency range, etc) of filter on the +12 supply line work (perhaps mimicking whatever filtering is being done within either the inverter or AC adapter)?
-->Also, the noise exists even if the car is only on ACC (not running), so I believe that rules out the alternator as a possible source