Same here, so I was scratching my head about the need for this. For the turntables that for some reason didn't have this (one example would be one I built mysel

Same here, so I was scratching my head about the need for this. For the turntables that for some reason didn't have this (one example would be one I built myself) you could get cheap strobe discs which you just put on the turntable, kind of like a tiny record.. start the turntable, and you would immediately see if it was in sync with (in this case) 50Hz.