NSM Serenade playing fast.

I have a strange problem with an NSM Serenade - it is playing records at about 47 rpm. This is the single motor, 2 belt carriage. I have replaced the belts, and the motor run capacitor. It still runs too fast! I noticed that the resistor in series with the motor cap is adjustable (the schematic shows a fixed 200 ohm resistor) so I tried adjusting this - still no change in the speed. Anyone else seen this and have a solution?

Hello Adrian,

the aluminium wheels come in different sizes. NSM marked them with a coloured dot. I know of these:

Colour/small diameter/large diameter
yellow / 9.2 / 34.5
blue / 9.48 / 34.65
green / 10 / 34.1
without / 9 / 35.1

The brown motors also slightly differ and are marked (the laquered screws don't count) with the colour of the best matching wheel. Sometimes motors and wheels got mixed up by earlier repairs.
I was not able to find a working formula to calculate the speed from the motor speed, all diameters and belt thicknesses, because the wheels are not flat, the belts unevenly strained and then thinner ...
Maybe Daniel Reuß can help to find the right wheel.

Regards,
Jens

Hi Jens, Thanks for this information - I was thinking the only way to fix it would be to machine down one of the pulleys, but that seemed wrong! Now I know there were different sizes it's not such a way out idea! The machine is a couple of hundred miles from me, I don't remember any coloured markings on the wheels but I will ask the customer to check.

Best Regards,
Adrian.