Why does my CRT TV crop the edges of every input?

If you can actually see recognizable parts of the image outside the normal viewing area, that points to excessive overscan or incorrect horizontal/vertical geometry rather than a problem with the connected devices. Some image loss is expected on CRTs, but a large crop may indicate that the width or height has been set too high. The service menu may offer horizontal size, vertical size, and position adjustments, although the exact options depend on the chassis and entering the wrong settings can create new problems.

This is most likely overscan. CRT televisions intentionally enlarge the picture slightly so the edges of the broadcast signal aren’t visible, and the amount can vary by input or by how the set’s geometry is adjusted. The tube itself doesn’t have rectangular pixels; the visible border is more likely the edge of the raster, the shadow mask, or picture information extending into an area that normally stays hidden. Check the normal picture-size or picture-position controls first. If the set has no user adjustment, reducing overscan generally requires service-menu geometry settings, so write down every original value before changing anything.

The dark structure around the picture may also be the shadow mask or the edge of the active raster, which can look like a couple of stray pixels. It isn’t a digital crop in the modern sense. Try a test pattern or an image with a clear border from each input; if the border disappears by the same amount every time, the TV’s overscan and geometry are responsible. Completely removing overscan may not be possible without leaving unstable edges or showing retrace and other artifacts.