Kramer TR-2YC s-Video Dual Isolation Transformer

When two pieces of video gear sit on different circuits, the shield between them becomes a second ground path and the picture pays for it: hum bars, a slow roll, a DC offset that shifts black level. The TR-2YC sits in the Y/C run and breaks that path. Luminance goes through a transformer, chrominance through a capacitor, and the two ends of the link no longer share a ground reference.

It is a passive box, so there is no supply to find and nothing to fail in a rack that is already full. An external ground terminal plus DIP switches let you choose how the video grounds are tied, which is what you need when the fault is on one leg and not the other. TR-2YC handles two channels; the single-channel version is the TR-1YC.