If your commodore 64 with new style motherboard has no sound, it is very likely just the internal fuse! If the fuse is broken on a new motherboard, your tape interface will not work AND there is no sound, but loading a game from disk is no problem. On an old motherboard, if the fuse is broken, the power led comes on but there is no image on tv. How to identify OLD or NEW motherboards: On the old motherboard the fuse is placed horizontal (left to right) On a NEW motherboard the fuse is placed vertical (top to bottom)