Put the strobe disc on the turntable, as though it is a record with the spindle of the turntable going through the hole in the strobe disc. There are usally four bands of bars on the disc, one each marked 60HZ and 50HZ and 33.33 and 45RPM. If you are in North America start with the 60HZ 33.33 rpm band, turn on your turntable and set it to 33.33. Hold the light directly over the disc with all other lights out. Adjust the speed control until the bars on the 60HZ 33.33 rpm band appear to stop moving. Repeat the process for 45rpm and you are home free. If you have other questions, please feel free to contact me directly, off board.
Marty
Marty