Leader LCG-396 Questions

[TinCanAlley]

I am experiencing a couple issue with this unit and am wondering if it's the unit, or the TVs I've attached it to.

First, when connected and turned on, I get the patterns noted on the buttons, but the first two TVs ('74 Zenith and '81 Hitachi) get a loud buzz through the speaker like I've experienced on the Zenith when there's commercial with lots of text. Someone said it's an overload of signal. Not sure exactly what that means as it doesn't do it with normal commercials or images.

Second, there is a setting to display red, green, blue and white by using a rotating switch. On the Zenith I see red, but blue and green either don't show up in color, or seem to be blends, not pure. On the Hitachi, red is red, but blue is more of a brownish green and green is teal. The Hitachi produces a very good image, so I'm not sure why it can't produce the correct colors.

The third TV is an LG G4 Oled and there is no buzz and the RGBW all produce the correct colors. This leads me to believe the unit is working as expected, so why do the other two TVs have issues with the signal and producing the correct colors?