[Vintage-Audio] Help! Sony Turntable Croaks!

[Phil]

> Is the speed changed by the belt being moved by these mechanics or by the
speed
> of the motor changing? The buttons do raise a piece of metal higher when
the
> speed changes from 33 1/3 to 45 rpm. Can't see how that would take up much
> tension though.

Duane.
If the speed mechanics move the belt up/down, what that does is slip the
belt over either of two sections of a dual diameter pulley on the motor
itself.   Not an unusual method for many older Turntables, especially if
they use an AC motor (as opposed to a DC Servo motor)  Even some of the DC
motor turntables use that method.  The other method of speed change that is
quite common on DC motor units is an actual change in motor speed that can
often be "fine tuned" via a control or thumbwheel.  On these there would be
no "slipping of the belt on a dual diameter pulley".

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