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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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20th Sep 2021, 9:55 pm | #1 |
Pentode
Join Date: Sep 2014
Location: London, UK.
Posts: 115
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Please help me ID this motor
Hi all
I'm puzzling slightly over a motor that is attached to a pedestal 16mm film projector I have inherited. A previous owner has retrofitted a varispeed circuit so that the projector can be run at speeds other than the standard 24fps. This circuit seems to work as intended but the motor is seriously underpowered and runs way too hot. Ideally, rather than replace the retrofitted circuitry, I would like to source a new more capable motor. The plate shows SERVO (the brand?) and a part number DM6S-3, a serial number and what I suspect is a date code of 8042. Searching online reveals nothing. A bit of testing reveals the following: With the projector running at 24fps the motor gets 19.5 v DC on the red and blue wires, and the rpm is approx 3300 (measured with a laser tacho). Activating the varispeed (knob on the front of the projector) simply decreases and increases the voltage and hence the rotation speed. The two grey wires are a bit of a mystery - they seem to have 3.6v AC at 24 fps and this again varies when the varispeed is used. Any ideas folks? More pics and details of the connected circuitry on request. ta Phil |
20th Sep 2021, 10:03 pm | #2 |
Heptode
Join Date: Feb 2003
Location: Garnant, near Ammanford, South Wales, UK.
Posts: 657
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Re: Please help me ID this motor
I expect the grey wires are a tacho winding on the front of the motor, with a magnet on the shaft inside.
Frequency will vary with speed. Richard
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20th Sep 2021, 10:24 pm | #3 |
Hexode
Join Date: Oct 2010
Location: Box End, Beds. UK.
Posts: 271
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Re: Please help me ID this motor
Out of curiosity what do you mean by "too hot", because some motors do run quite warm?
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20th Sep 2021, 10:41 pm | #4 | |
Pentode
Join Date: Sep 2014
Location: London, UK.
Posts: 115
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Re: Please help me ID this motor
Quote:
Whoever did the mods to the machine didn't add any cooling for the motor - I have pondered adding a fan as another possible solution. |
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20th Sep 2021, 10:47 pm | #5 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,518
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Re: Please help me ID this motor
Also out of curiosity, what make/model is the projector?
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20th Sep 2021, 11:01 pm | #6 |
Pentode
Join Date: Sep 2014
Location: London, UK.
Posts: 115
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Re: Please help me ID this motor
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20th Sep 2021, 11:14 pm | #7 |
Dekatron
Join Date: Jun 2009
Location: Staffordshire Moorlands, UK.
Posts: 5,271
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Re: Please help me ID this motor
That 'servo' logo is Japan Servo Motor Co, now part of Nidec Corporation. They are one of the world's biggest motor manufacturers. They make Indesit's washing machine motors among other things.
I'm guessing the grey wires are a magnetic speed sensor, I assume the motor is free to turn and they dont release a brake!
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Kevin |
21st Sep 2021, 8:08 pm | #8 |
Octode
Join Date: May 2009
Location: Stevenage, Herts. UK.
Posts: 1,518
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Re: Please help me ID this motor
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21st Sep 2021, 8:33 pm | #9 |
Hexode
Join Date: Feb 2007
Location: Chesterfield, Derbyshire, UK.
Posts: 483
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Re: Please help me ID this motor
Why not just install a small fan to help cool the motor, that is what is sometimes done in industrial inverter drive applications then the motor is run lower than it's rated speed.
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23rd Sep 2021, 8:47 pm | #10 |
Pentode
Join Date: Sep 2014
Location: London, UK.
Posts: 115
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Re: Please help me ID this motor
Thank you all for your help on this one, most useful, we are up and running now.
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