Heb de manual gecheckt (waarvan ik weinig verwachtte) en het stond er in:
Vierde laag is blijkbaar niks.STROBEDOTS- The dots around the edge of the platter are used in conjunction with the light located inside the motor ON/OFF switch. While the platter is in rotation, the dots help to indicate the speed of rotation. The speed is lower than the displayed speed (33,45,78) when the dots are flowing to the right. It is higher than the displayed speed (33,45,78) when the dots are flowing to the left. When the strobe is stopped, the platter is rotating at the displayed speed.