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ricard · 22nd Jan 2013, 9:46 am

Did an experiment to boost the supply voltage in order to see if that would help. I was thinking of the Beocord 2000 I have which also has a Papst synchronous motor, where in play mode there is a resistor in series with the motor, whereas it gets the full supply voltage in the wind modes where more torque is needed.

Added a 45 AC source from a second transformer in series with the motor, which brought the supply voltage from 260V up to 305V. Interestingly enough, it still takes half a minute before it actually reaches its synchronous speed. I was thinking along the lines of the supply voltage for some reason originally being to low for it to run properly, but I'm now thinking that the added voltage causes the motor to warm up faster, hence it takes shorter time for it to start working properly.

I'm wondering if I've reassembled the motor incorrectly, causing something not to align properly, but short of some part of the thrust bearing at the bottom of the machine falling out during disassembly I cannot really think of what. And if the thrust bearing were missing (basically just a steel ball) it would be a lot noisier.

Colin, did you have a spare motor on hand? I'm thinking of replacing it, as the rest of the electronics has responded well to capacitor replacement and alignment.

22nd Jan 2013, 9:46 am	#28
ricard Octode Join Date: Mar 2006 Location: Lund, Sweden Posts: 1,632	Re: Sluggish synchronous motor Did an experiment to boost the supply voltage in order to see if that would help. I was thinking of the Beocord 2000 I have which also has a Papst synchronous motor, where in play mode there is a resistor in series with the motor, whereas it gets the full supply voltage in the wind modes where more torque is needed. Added a 45 AC source from a second transformer in series with the motor, which brought the supply voltage from 260V up to 305V. Interestingly enough, it still takes half a minute before it actually reaches its synchronous speed. I was thinking along the lines of the supply voltage for some reason originally being to low for it to run properly, but I'm now thinking that the added voltage causes the motor to warm up faster, hence it takes shorter time for it to start working properly. I'm wondering if I've reassembled the motor incorrectly, causing something not to align properly, but short of some part of the thrust bearing at the bottom of the machine falling out during disassembly I cannot really think of what. And if the thrust bearing were missing (basically just a steel ball) it would be a lot noisier. Colin, did you have a spare motor on hand? I'm thinking of replacing it, as the rest of the electronics has responded well to capacitor replacement and alignment.