Monday, September 24, 2018

Fixing the 60 Hz Motor speed and heat

As the jukebox comes from US the turntable motor runs on 60 Hz.
Here in Sweden we have 50 Hz, so to correct that I bought a spring from Stamann in Germany to mount on the motor drive shaft. Well it did fit perfect BUT the speed was around 40 rpm so it was just a waste of time and money.

Next problem was the motor was running heat caused of the 50 Hz, motor was around 70 degrees C HOT and the windings will probably melt down over time.
A large metal resistor (82 ohms 25W) is the solution here, voltage went down to 100VAC and the heat went down to 35-40 degrees C, I can live with that but a 50 Hz motor should be my final solution.

The motor in pieces, no radial play in the bearings (will cause rumble), and a 2,5mm axial play seems ok.


As it was impossible to achive the speed 45 rpm it ended up in the workshop at my work.
With the spring diameter in mind I estimated the outer diameter to be 5,35 mm.

The new turned ABS tube installed and slightly grinded in place now gives 45,1 rpm :-)


 Temperature/voltage after adding the 82 ohms resistor in line with the 120 VAC. 
Note the resistors temperature!


This cooling fins will do it!

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