Phono3S it's humming again.

[bikerhifinut]

Originally Posted by John Caswell

Hi Andy,
Placing a die cast case around the Gyro PSU will not help as it is an electromagnetic field the is causing the problem. Only mumetal or distance will help and that is a seriously expensive exercise.
Why not do as I did (cos I am lazy and cannot be bothered to change over the belt) and build yourself a new PSU with a toroidal transformer and switched voltages to change speeds, assuming that you have the DC motor, as opposed to the DC Papst motor. It is not very difficult using a standard 3 pin regulator. Of course if ll you play is 33 rpm is is even easier.

John

Intriguing John, I imagine all it is is a voltage adjustment? I would need a strobe mat and light to adjust/check it I guess. The original is a small EI transformer and a 317 or similar regulator, doesn't look anything special.
So do you put the belt on the big motor pulley or the small (33rpm) one?
And I guess for 2 speed operation a switch between two trimpots on the adjustment leg of the device.?

A