Please help me ID this motor - UK Vintage Radio Repair and Restoration Discussion Forum

phildil · 20th Sep 2021, 9:55 pm

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

Richard · 20th Sep 2021, 10:03 pm

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

trsomian · 20th Sep 2021, 10:24 pm

Out of curiosity what do you mean by "too hot", because some motors do run quite warm?

phildil · 20th Sep 2021, 10:41 pm

Quote:

Originally Posted by trsomian

Out of curiosity what do you mean by "too hot", because some motors do run quite warm?

Well .... I've not measured the temp but too hot to touch after say 15 minutes operation at 24fps, and much hotter when running at a slower speed.

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.

wd40addict · 20th Sep 2021, 10:47 pm

Also out of curiosity, what make/model is the projector?

phildil · 20th Sep 2021, 11:01 pm

Quote:

Originally Posted by wd40addict

Also out of curiosity, what make/model is the projector?

Fumeo HL3000 pedestal projector for cinemas

From around 1980

it's also worth adding that this motor runs the "mech" i.e. the sprockets and the shutter - it's not responsible for driving the takeup spool.

McMurdo · 20th Sep 2021, 11:14 pm

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!

wd40addict · 21st Sep 2021, 8:08 pm

Quote:

Originally Posted by phildil

Quote:

Originally Posted by wd40addict

Also out of curiosity, what make/model is the projector?

Fumeo HL3000 pedestal projector for cinemas

It's quite a beast!

I remember Fumeo making one of the last available Super 8 projectors (at a price!).

wave solder · 21st Sep 2021, 8:33 pm

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.

phildil · 23rd Sep 2021, 8:47 pm

Thank you all for your help on this one, most useful, we are up and running now.

20th Sep 2021, 9:55 pm	#1
phildil Pentode Join Date: Sep 2014 Location: London, UK. Posts: 115	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 Attached Thumbnails

20th Sep 2021, 10:03 pm	#2
Richard Heptode Join Date: Feb 2003 Location: Garnant, near Ammanford, South Wales, UK. Posts: 657	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 __________________ BVWS member.

20th Sep 2021, 10:24 pm	#3
trsomian Hexode Join Date: Oct 2010 Location: Box End, Beds. UK. Posts: 271	Re: Please help me ID this motor Out of curiosity what do you mean by "too hot", because some motors do run quite warm?

20th Sep 2021, 10:47 pm	#5
wd40addict Octode Join Date: May 2009 Location: Stevenage, Herts. UK. Posts: 1,518	Re: Please help me ID this motor Also out of curiosity, what make/model is the projector?

20th Sep 2021, 11:14 pm	#7
McMurdo Dekatron Join Date: Jun 2009 Location: Staffordshire Moorlands, UK. Posts: 5,269	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! __________________ Kevin

21st Sep 2021, 8:33 pm	#9
wave solder Hexode Join Date: Feb 2007 Location: Chesterfield, Derbyshire, UK. Posts: 482	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.

23rd Sep 2021, 8:47 pm	#10
phildil Pentode Join Date: Sep 2014 Location: London, UK. Posts: 115	Re: Please help me ID this motor Thank you all for your help on this one, most useful, we are up and running now.