It's not guaranteed: I always use this face when I see a complaint of 46V plus banding in the display, since it's a bit chicken and egg. The display may be pulling the voltage down (it's duff - expensive repair) or the supply might have gone bad, to which the display responds by doing tricks like this (cheap repair).

Generally, if the display goes dimmer without bands when the voltage drops, then the glass is still good. As soon as I hear "bands", I reach for the soldering iron and wire clippers.....

What happens if you turn down the brightness with the dimmer? Does it stop banding as the brightness is reduced?