NotTaR of Television Sets : Vertical brightness or color bars       
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Vertical brightness or color bars

These are typically more or less equally spaced possibly more evident at the left side of the screen. They result only in brightness or color variations, not deflection speed. Diagonal lines are straight and not squiggly.

Note that the appearance of these bars differs from those caused by ringing in the deflection circuits where diagonal lines will show a squiggling stair-step appearance.

The most likely cause is a dried up electrolytic capacitor in the scan derived power supply for the video or chroma circuits or video output. Check for this ripple with a scope or test/replace any suspect capacitors.