Vintage Turntable repair: Can I fix a Perpetuum Ebner from 1958 - part 2 - Calculating the Motor Speed

RE: Vintage Turntable repair: Can I fix a Perpetuum Ebner from 1958 - part 2 - Calculating the Motor Speed

RPLaJeunesse — Tue, 24 Feb 2015 21:34:54 GMT

Jan, you might want to redo your spreadsheet using 16-2/3 RPM as the target speed, not 16 exact. IIRC that speed was intended to be exactly half the 33-1/3 speed, which made cutting the low speed master easier. A 16-2/3 master could be done on a record lathe at 33-1/3 by running the master tape at twice the original speed. At 16-2/3 the motor speed calculates closer to 2900 RPM. The 2940-ish speed you calculate seems about right for a 50Hz motor, as the no-slip speed for a 2-pole motor would be 3000 RPM. But any non-synchronous motor has some small amount of slip, and thus runs a bit slower. In the 60Hz world motors are 1800 and 3600 RPM before slip, with 1750 RPM being the number I remember for a 4-pole motor with slip.

RE: Vintage Turntable repair: Can I fix a Perpetuum Ebner from 1958 - part 2 - Calculating the Motor Speed

D_Hersey — Thu, 12 Feb 2015 22:53:02 GMT

I saw your earlier discussion of this device, late afternoon, don't have the will budget to go look it up at the moment, tried a little google fu the other day. Can you confirm that the motor is "asynchronous capacitor-run" type? Did you find any non-polarized electrolytics in the thing?

You probably know volumes more about drive belts than me. I cannot tell from the illustration, it seems you are doing it rightly, but make sure you are measuring the pitch diameters of the pulleys rather than the inside diameters.

RE: Vintage Turntable repair: Can I fix a Perpetuum Ebner from 1958 - part 2 - Calculating the Motor Speed

ipv1 — Thu, 12 Feb 2015 20:09:46 GMT

Very interesting build. You should consider making it a haunted object like with a small projector for the ghost and spooky old songs and stuff. It could work via twitter or gmail notifications... Imagine that! A ghost telling you that you've got mail! [View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-1fc02b34-1572-4c34-9bae-7f4a46bd8aec/contentimage_5F00_2516.png:16:16]