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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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25th Jan 2020, 4:26 pm | #1 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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DUAL technical info needed
Anyone have any technical info on this DUAL motorized turntable?
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25th Jan 2020, 5:30 pm | #2 |
Dekatron
Join Date: Nov 2008
Location: Whittlesey, near Peterborough, Cambridgeshire, UK.
Posts: 3,758
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Re: DUAL technical info needed
Could you post pictures of the motor, please?
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26th Jan 2020, 10:25 am | #3 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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Re: DUAL technical info needed
I thought that should have been included! Thanks for the interest.
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26th Jan 2020, 11:59 am | #4 |
Triode
Join Date: Jan 2005
Location: Michelstadt, Germany
Posts: 19
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Re: DUAL technical info needed
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26th Jan 2020, 1:31 pm | #5 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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Re: DUAL technical info needed
Danke, das sieht identisch aus! Is it a good idea to bring the motor up to voltage using a variac? Can this do any damage?
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26th Jan 2020, 1:41 pm | #6 |
Dekatron
Join Date: Nov 2008
Location: Whittlesey, near Peterborough, Cambridgeshire, UK.
Posts: 3,758
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Re: DUAL technical info needed
I have three identical motors in acoustic gramophones, but with spring mechanisms attached, so that the motor can be either wound up, or plugged into an electrical socket.
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26th Jan 2020, 3:22 pm | #7 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: DUAL technical info needed
By coincidence I picked up the attached motor assembly at my local car boot yesterday.
It was in a box of junk that would otherwise be skipped eventually, I had to rescue it (honest). I assume it is also from an acoustic gramophone. How does the governor work? is it purely mechanical or does it operate a switch when overspeed? Peter Last edited by Electronpusher0; 26th Jan 2020 at 3:23 pm. Reason: typo |
26th Jan 2020, 4:08 pm | #8 |
Guest
Posts: n/a
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Re: DUAL technical info needed
Purely mechanical, the disk bit rubs on the felt bit when up to speed slowing it down. Shunt motors like that don't mind too much when loaded and they slow down gracefully.
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26th Jan 2020, 5:21 pm | #9 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: DUAL technical info needed
Thanks, Any idea what voltage the motor runs at? unfortunately the voltage on the motor rating plate is blank.
I thought possibly it was 220V being French? Peter |
26th Jan 2020, 6:07 pm | #10 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: DUAL technical info needed
I'd run it up on a variac if you can, start at 110-120V and feel the temperature of the motor, then crank it up to 150V, then 200, then perhaps 220-240. All the time keep an eye on the temperature of the motor.
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26th Jan 2020, 6:26 pm | #11 |
Tetrode
Join Date: Oct 2016
Location: Manchester, UK.
Posts: 78
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Re: DUAL technical info needed
The unit in the Radio Museum link has a voltage selector which I think must be located under the platter. Have you removed the platter to see if yours has the same?
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Mark |
26th Jan 2020, 6:48 pm | #12 | |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
Posts: 2,288
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Re: DUAL technical info needed
Quote:
Peter |
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30th Jan 2020, 10:22 am | #13 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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Re: DUAL technical info needed
Just an update. The speed control arm has a felt piece that rubs against the disc on the motor. This had worn down so much as to become ineffective, so I replaced it with a rubber tap washer which does a reasonable job, although felt would be better. I stripped the tone arm to see why their was no audio (other than that which you could hear directly from the pickup head) The wiring had broken, and replacing this and reassembling was a painless exercise. To my astonishment the audio plays well through one of my DIY SE valve amps. All in all a happy ending! The tx in the pickup head assembly has a selector knob on top, which selects different tappings ranging from 200 - 2kOhm. This makes a difference to the volume.
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