The jukebox will outputs a power level of 15 when playing music discs. The comparator is not affected.
Jukeboxes emit a redstone signal when they contain a music disc (no comparator!)
There's a problem with the record player
Jukeboxes give off a redstone signal Without a comparitor when playing music
Hoppers not working when next to jukebox
Jukebox with disk activates TNT