By pressing the Power button (1) the record player is switched on or off. If switched on the Thorens-logo in the centre of the front panel will be illuminated as well as one of the speed indicator LEDs. Select the desired speed by means of the speed selector buttons (4+5) and press the Start button (2) in order to start the motor. The Start LED will then be lit. When the motor is running you may change between speed without having to stop the mo- tor beforehand. If the Start button (2) is pressed once again the motor will stop and the respective LED goes off. If switched on the next time the previously selected speed will be indicated.
HINT: the TD 550 is equipped with an intelligent start-up control which within the first four seconds makes the mo- tor initially running at half the selected speed and thus is reaching the rated speed more quickly than without this control. This applies also to the rated speed of 45 rpm.
Both 33 and 45 rpm have been factory-calibrated by means of a very precise 300-Hz stroboscope disk. The built-in motor control circuitry is capable to maintain precise rpm without any deviations for many years to come. In the event that you would like to fine-adjust the speeds yourself you can do this via the potenti- ometers (11+13) provided at the rear panel and by using a fine, bladed screwdriver (trimmer). However we recommend to keep the factory settings if you don‘t have access to a precise stroboscope disk and lamp in order to control the adjustments.
An explanation of operational elements and connec- tions at the TD 550 is given in Figure 1 on page 25 of this manual.
