How to get full picture on CRT television sets

[Electronic M]

The RF modulator won't fix the lines. Banderson was pointing out a redundancy in your system. The redundancy is neither good or bad for the "lines".

The proper name for the "Black lines" you see is letterboxing and pillarboxing. Letterboxing is when there are horizontal black bars above and below the picture. Pillarboxing is the correct term for when theres vertical black bars are on either side of the picture. It's possible to have both at once. If you don't call a problem by its proper name it may confuse some people reading/responding.

Letterboxing is one* way to convert 16x9 widescreen aspect ratio programs to 4x3 which is the aspect ratio of older TVs. Pillarboxing is the best way to convert old 4x3 programs to 16x9.

*The other way was called pan and scan in the era of VHS, but most boxes call it zoom...Zoom fills the screen on 4x3 TVs but it cuts the sides off new widescreen programs.
Most people prefer letterbox to Zoom since they don't want to miss action going on on the far sides of the picture.