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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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4th Nov 2017, 2:12 pm | #1 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Wearite motor hums
There's a Ferrograph 6 on the bench with a noisy motor. It hums.
I can stop the humming by inserting a screwdriver between the motor laminations and the frame but this isn't an ideal solution. The rubber mounts seem okay, but might not be. Has anyone any ideas?
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5th Nov 2017, 9:34 pm | #2 |
Pentode
Join Date: Nov 2010
Location: Tenby, Pembrokeshire, Wales, UK.
Posts: 139
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Re: Wearite motor hums
Hi,
Is it a reel motor or the capstan motor that 'hums'? |
6th Nov 2017, 7:41 am | #3 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Re: Wearite motor hums
Capstan.
Bearings are good, with no power it rotates silently. Could be a faulty capacitor I suppose?
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6th Nov 2017, 10:01 am | #4 |
Banned
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
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Re: Wearite motor hums
All AC motors hum, its a question of degree. But as you describe it, stopping VIBRATING when you load the core against the cage, it does sound like a loose lamination stack or cage problem.
Are all the bolts tight? If it's the lams rattling, get the motor warm, 50C will do, and give it a coat of varnish on the lams. As it cools it will draw it in and tighten the core. |
6th Nov 2017, 11:08 am | #5 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Re: Wearite motor hums
This one hums much more than usual for a Ferrograph capstan motor. There's no evidence of loose laminations, the usual amount of varnish is there and the rivets seem tight. All the nuts are tight, first thing I checked!
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6th Nov 2017, 11:35 am | #6 |
Pentode
Join Date: Nov 2010
Location: Tenby, Pembrokeshire, Wales, UK.
Posts: 139
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Re: Wearite motor hums
I suggest checking the phase-shift capacitor for value and leakage. From my experience if it 'loses' capacity then the motor struggles to 'lock' onto speed and may hunt. Maybe you are having another problem with this?
Have the rubber mounts gone too hard? |
6th Nov 2017, 12:00 pm | #7 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Re: Wearite motor hums
Rubber mounts seem okay, there's flexibility in there which seems as usual.
The Hunts "Therminol" capacitor reads 0.83µF for a stated capacity of 0.75µF ±10%, ESR reads 1.1Ω and Vloss is 0.2%.
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6th Nov 2017, 10:12 pm | #8 |
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Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
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Re: Wearite motor hums
If its reading high in value, even just in the 10%, it is possible leaky. Are you using a bridge or a Chinese magic tester?
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7th Nov 2017, 7:43 am | #9 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Re: Wearite motor hums
A quick check with the Chinese tester, my Heathkit bridge is not in that workshop.
Leaving the capacitor out of circuit reduces the hum a lot, so I’ll dig in the box of spares today and find something suitable.
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10th Nov 2017, 7:41 pm | #10 |
Hexode
Join Date: Aug 2017
Location: Taunton, Somerset, UK.
Posts: 318
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Re: Wearite motor hums
Your first comment refers to the action of the screw driver which in essence is acting as a wedge. I used to work for GEC M/Cs (many moon's ago) and the fitter's were forever making wedges and hammering them in to stop the associated problems.
I would do this using home made wedges out of wood or plastic and then varnish as per Boater Sam recommendations. |
11th Nov 2017, 9:19 pm | #11 |
Tetrode
Join Date: Aug 2005
Location: Leicester, Leicestershire, UK.
Posts: 68
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Re: Wearite motor hums
Mention above of loose laminations, but that would more likely cause a buzz than hum.
One - albeit unlikely - thought: could this by any chance be a 110 volt motor fitted where a 240V one should be? This is only a possibility if the deck has never been run for more than a few minutes, otherwise the motor would cook and burn out!
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Andrew B. |
12th Nov 2017, 10:41 am | #12 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Re: Wearite motor hums
I have some replacement rubber motor mounts and a replacement capacitor on order. One or both may fix the problem.
There’s no evidence that the motor is 110v or of loose laminations. Further news to follow.
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13th Nov 2017, 1:17 pm | #13 |
Heptode
Join Date: Jan 2008
Location: Shrewsbury, Shropshire, UK.
Posts: 843
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Re: Wearite motor hums
Your mention of rubber mounts reminds me that I need to order some for one of my Ferrographs.
I found something similar, but not really an exact replacement. It would be good to know where you are obtaining them from. Thanks, David. |
13th Nov 2017, 7:52 pm | #14 |
Hexode
Join Date: Aug 2017
Location: Taunton, Somerset, UK.
Posts: 318
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Re: Wearite motor hums
My reference to wedges given previously was not particularly associated with loose laminations but more the problems arising out stray eddy currents that often occur within motors and transformers.
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14th Nov 2017, 11:43 am | #15 |
Nonode
Join Date: Aug 2010
Location: Resolven, Wales; and Bristol, England
Posts: 2,612
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Re: Wearite motor hums
Mine came from Terry at Ferrographworld.com, he's on this forum too as terry123.
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