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Spare part for tubular ripple


Ynot
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Got a couple of old-school tubular ripples on loan for a show coming up - one works fine but the second isn't doing any rippling - ie the motor isn't turning..

 

First issue I think is the serrated tube isn't tight to the spindle, but even then that wouldn't help if it was as the motor dinnae turn anyway.

 

I've had the end off and there's what I assume is a smoothing capacitor in line with the live feed after the switch - I get 230v at the in terminal there, but only about 80v on t'other side so my simple thought was that this is duff.

Proven in fact by shorting out the cap means the motor starts to turn.

 

So - ideally I'd like to replace that capacitor but sadly the labelling on the case is extremely faint and no way can I read what it is to look for a spare part.

 

Anyone have any ideas on that one??

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Does the motor have 3 wires coming out of the windings? If so, it will most likely be a capacitor-start single phase induction motor. Can you have a look inside the working one and see what's there?

From the pic I took the other day to try and blow up for a clearer image (failed!) yes it looks as though it does have 3 wires...

 

 

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Does the motor have 3 wires coming out of the windings? If so, it will most likely be a capacitor-start single phase induction motor. Can you have a look inside the working one and see what's there?

From the pic I took the other day to try and blow up for a clearer image (failed!) yes it looks as though it does have 3 wires...

 

 

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I'm seeing four wires in the picture (two grey, orange, blue) plus the earth. I can't see where the other leg of the capacitor goes once it comes out of the heatshrink?

This is an AC device, so nothing is a "smoothing capacitor", there is no rectifier giving DC.

 

As pmiller056 says, the "normal" arrangement would be an AC motor which has two windings on it. This gives four ends, although one end of each winding goes to mains neutral, so often the two are joined inside the motor to give only three wires. One of the other ends goes directly to mains live, and the other to mains live via a capacitor. The capacitor gives enough phase shift in the AC voltage to make the motor start (and do so in a predictable direction!) although the motor will probably run (badly) without the capacitor once started. The capacitors used are typically (but not always!) 250V AC rated types, value between 0.1 and 10 microfarads. This can make it easier to guess what the markings mean!

If (as you say) this capacitor is in series with the sole live feed, this isn't it, because there should be a lead which bypasses the capacitor into the other winding of the motor as well.

The other possibility with a small, low-RPM motor like this is that it only has two wires from the motor (one winding), with the starting being handled magnetically within the motor. This was quite common on small, slow, AC motors like clocks. These motors would not normally need a capacitor at all, but it's (I suppose) possible that someone could have converted a 110V motor to run on 240V using a capacitor in series with the motor to drop the voltage? This would then be connected directly in series with the motor (two wires) from the mains live. I can only see this as an after-market solution to not being able to get the correct voltage motor, but I would also expect an original capacitor to be fixed down, not floating on the end of wires with heatshrink ...

 

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The wiring in your picture (ie four wires plus earth) looks similar to that of a projection screen motor which I've recently been investigating. In my case the two grey wires go to one end of the motor windings. They are joined together outside the motor and connected to mains neutral . The red wire and the blue wire are joined to the other end of the motor windings and a capacitor is connected between them. The live feed is then applied to red or blue, depending on the direction of the rotation required (eg for 'Up' the red wire is connected to live and this then feeds the red winding directly and the blue winding via the capacitor. For 'Down' the blue is connected to live which then feeds the blue winding directly and the red via the capacitor.).

In my case one of the motor windings has failed with the result that when a button is pressed then occasionally the motor starts running in a random direction but usually it fails to start at all. I'm currently looking for a replacement......

 

Ths may or may not be relevant in the case of a tubular ripple (I don't know if it's possible to change the direction of rotation on them). However if the wiring arrangement is similar to my screen motor then the capacitor in the photo is not the 'start' capacitor as the one in the photo is apparently connected to the two grey wires (and in series with the mains neutral?) rather than between the red and blue live feeds. It could however be there to drop the incoming voltage for the motor as suggested by Richard.

Edited by Hilary Watts
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https://uk.rs-online.com/web/p/ac-motors/4410423

 

 

Is one source of pictures and maybe inspiration.

 

Four wires suggests an AC capacitor run motor where the connections of mains and capacitor at the motor determine the direction of rotation.

 

For motors of that form there are different numbers of motor poles and different gearboxes available to get speeds from 100rpm to clock speed rotation, With luck the motor may allow you to change the gearbox over to a new motor or simply the capacitor may be fried and need a replacement. Look at the good one also for clues about the motor and the capacitor

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Philips (and others') caps like this often have the value printed on the top face (opposite face to the lead entry) so it would be worth having a careful look there.
Yep - there's something there but too faded for my aged eyes to make out... :(

 

The wiring in your picture (ie four wires plus earth) l <snipped>

OK - couple of better pics of the wiring.

 

PXL-20211021-181317315.jpg

 

PXL-20211021-181317315.jpg

 

Philips (and others') caps like this often have the value printed on the top face (opposite face to the lead entry) so it would be worth having a careful look there.
Yep - there's something there but too faded for my aged eyes to make out... :(

 

So yes - L & N both going to the motor with the 2 grey wires ganged together the other side of the L wire thru the cap.

I'm pretty sure the cap is the problem, so need the value so I can get a replacement.

Edited by Ynot
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At the risk of statin' the bleedin' obvious have you looked at the RS page for that stock no? There's a data sheet there which tells all! ?

Well - I'd not thought of looking at the motor part for the cap, but so it is!!

Thanks for the point into the obvious direction :D :D :D

 

Will get one ordered now

:D

 

 

 

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