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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details.

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Old 12th Jun 2018, 5:50 am   #41
Lucifer
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Default Re: Wiring a desk electric fan.

''That's very funny. It's not a rare thing or anything, but you have (one of) THE classic bits of test gear. Like someone apologising for ignorance of wrist watches and then pulling something out of a draw and saying 'it appears to be Swiss - Rulex? Ralex?' ''

I'm a collector, I even have some old classic radios. Apart from my computer, the most modern commodity I own is a 1920's Bergere suite

I've now replaced the soldering on the winding to cord wires with connectors and taken fresh readings with my digital volt meter, I have constant readings of 22.5 between the grey and green wires/grey and black wires. No registering on anything between the brown wires with everything else wildly flashing and fluctuating.

The brown wire I have attached to the brown/white striped wire from the winding. I'm presuming this is a live wire.

Last edited by Lucifer; 12th Jun 2018 at 6:00 am.
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Old 12th Jun 2018, 9:52 am   #42
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Default Re: Wiring a desk electric fan.

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I have taken a wiring diagram of a modern fan(image enclosed) I don't know whether or not this will be the same as the wirings from my fan. I am also experiencing a lot of fluctuation whilst taking readings between the wires.(image enclosed of my meter)
Some DMMs don't work well trying to measure the resistance of an inductive load like a motor winding. If you don't have another meter, you could try putting 100 ohm resistor in series with the meter and then subtracting it from the readings if they then settle down OK.

Edit- just seen the AVO7! You'll only need the D cell for lowish resistance readings, the hard to get 15V one is used for the highest resistance range only.

Take care not to connect yourself across the motor winding when connecting or disconnecting the old meter, it can generate a nasty voltage spike as it is disconnected! (Same principle is used in a car ignition coil)
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Old 12th Jun 2018, 10:05 am   #43
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Default Re: Wiring a desk electric fan.

I don't think we're going to get anywhere with this until we get some reliable resistance readings.

Question for the AVO experts. Is a 15V battery necessary if only the low resistance ranges of the OP's AVO are used?
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Old 12th Jun 2018, 10:15 am   #44
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Default Re: Wiring a desk electric fan.

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I don't think we're going to get anywhere with this until we get some reliable resistance readings.

Question for the AVO experts. Is a 15V battery necessary if only the low resistance ranges of the OP's AVO are used?
No.
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Old 12th Jun 2018, 10:22 am   #45
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Default Re: Wiring a desk electric fan.

So the OP fits a 1.5V D cell to his meter, sets the AC switch to DC, sets the DC switch to the lowest ohms range, connects the meter leads together, zeroes the pointer at the right end of the scale using the set zero control and then takes readings from the fan motor leads?
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Old 12th Jun 2018, 10:47 am   #46
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Default Re: Wiring a desk electric fan.

The 15 volt battery is for the ohms times 100 range only.
The high ohms range is needed for testing one or two special components like stick rectifiers but for this task it will not be needed.
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Old 12th Jun 2018, 12:18 pm   #47
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Default Re: Wiring a desk electric fan.

That's an old Avo 7, so won't need a 15 volt battery. It needs 9 volts, as in 2 x 4.5 volt, I usually just patch a PP3 9 volt type in these to make them work on the high ohms range. However, as has already been said, he just needs the lower range, so solder a couple of wires onto the ends of a standard 'D' cell and connect them to the two terminals, observing polarity - easy!

This fan 'may' have a 'brush' type motor, which by now will likely have a very mucky commutator, thus giving the variable readings. I would try giving the motor shaft a 'twiddle' while taking a reading and see if it makes the readings go wild. If it does, then a bit more 'twiddling of the shaft may get it cleaner and contacting better - after that it's a strip and clean job.
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Old 12th Jun 2018, 12:21 pm   #48
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Default Re: Wiring a desk electric fan.

Judging by the pictures the armature has been removed, so it will be quite easy to see whether it has a commutator.
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Old 12th Jun 2018, 12:44 pm   #49
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Default Re: Wiring a desk electric fan.

Ah, I didn't spot that. Well, in that case it's unlikely that the commutator to brush connections will be causing the variable readings (that's if it does have brushes etc.), unless the brushes and their springs are still dangling about and touching each other, I'll go and study the pictures a bit closer.
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Old 12th Jun 2018, 12:47 pm   #50
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Default Re: Wiring a desk electric fan.

I've just checked the picture in post #4, and it looks to me as though the armature is still in place in the motor - or am I missing something?
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Old 12th Jun 2018, 1:27 pm   #51
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Default Re: Wiring a desk electric fan.

The front and back casting photos in post 4 don't look as though there are brush-holders present. And the stator photo in post 1 looks more like a multiple induction motor stator than a DC or universal motor stator (it could also be a synchronous motor stator, but I think we can discount that).
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Old 12th Jun 2018, 1:32 pm   #52
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Default Re: Wiring a desk electric fan.

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I've just checked the picture in post #4, and it looks to me as though the armature is still in place in the motor - or am I missing something?
The picture in post #1 shows the armature has been removed. Presumably to access the wiring?
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Old 12th Jun 2018, 3:20 pm   #53
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Default Re: Wiring a desk electric fan.

I don't think I'll bother to go down the route of attempting to use my Avometer, why I can barely use the digital example and then only in one position. A similar analogy would be a person attempting to re-pivot a balance staff on a wristwatch without even knowing how to open the case back. Incidentally, I acquired the meter upon a friend's demise over 20 yrs. ago and never even looked at it until now.

Although a relatively simple task for a person with basic radio technology knowledge, I think that rewiring my fan is going to be a bridge too far for me. If anyone resides in the Woodford area of London, maybe I could pay them to locate which wires go where.

I did remove the armature for the purposes of photographing the windings and there aren't any brushes. In fact, I dismantled the entire fan in order to check the mechanical parts etc.

I enclose a primitive diagram of how I think the wiring might be and you will note that there are more question marks than at best, 'guesstimations
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Old 12th Jun 2018, 6:13 pm   #54
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Default Re: Wiring a desk electric fan.

I meant of course, that I removed the com, as opposed to the armature.
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Old 13th Jun 2018, 9:55 am   #55
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Default Re: Wiring a desk electric fan.

I think you meant armature, part of which is the commutator.
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Old 13th Jun 2018, 11:57 am   #56
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Default Re: Wiring a desk electric fan.

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I think you meant armature, part of which is the commutator.
Therein lies part of the problem, I don't even understand the terminolgy, never mind all the technical advice that is being proffered. I think one has to dumb down and draw simple pictures when transferring information to to a person who has limited knowledge on any particular subject.

Anyway, I digress, I have briefly spoken to an acquaintance who has a modicum of electrical knowledge and he, rightly or wrongly, is of the opinion that I am wasting my time attempting to take reading between the various permutations of wires. He states that I will need to locate the common ( by which I presume he means neutral) wire and individually measure the resistance values between the aforementioned and the other 4 wires emanating from the winding. Only then will I be able to determine which wire goes where.
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Old 13th Jun 2018, 12:20 pm   #57
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Default Re: Wiring a desk electric fan.

To me that motor looks like it just has a rotor and stator and no commutator.
If it is anything like a scrap modern fan I was given there is a common and three taps.
Just find the two wires with the highest resistance and then connect an old style light bulb the live mains wire and the other end to your motor.
It should run at reduced speed allowing you to measure the voltages on the taps.
Just be careful with the high voltage.
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Old 13th Jun 2018, 12:25 pm   #58
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Default Re: Wiring a desk electric fan.

I know exactly what I'd do if that were mine, and that is to use a standard light bulb in series with the mains and flash it onto the various connections to see what was what.

The above method is what's known as using a 'LAMP LIMITER' - do a search on the forum for a LOT more information.

You can't do much harm with a standard tungsten filament 60 watt bulb in series with the mains, although you MUST take care with live connections and the risk of SERIOUS ELECTRIC SHOCK if you were to touch one! I have to highlight the safety aspect of working with live mains, as what I may do being very experienced with such things, may be dangerous for the less experienced.

I had the same problem with my central heating pump a few years ago when the three speed control switch unit completely burnt out. It had virtually been on fire and all I was left with was the remains of the charred circuit board and the blackened ends of the wires from the body of the pump motor. After doing the metering of the various wires as you've tried to do above, I made the final connection to the mains via a light bulb in series with the supply - it was the middle of winter and I wasn't going to risk a flash and a bang and a blown pump motor if I'd got it wrong. I had got it right with the pump motor running and the lamp running about a half 'glow' of the filament. I then hard wired it in fast speed setting and it's been like that ever since.

I think that's about the only time I've ever used the lamp limiter method, although others have a unit ready made up with bypass switching and different wattage lamps, and use them all the time for powering up unknown vintage radio sets etc.

Edit: Great minds think alike (as they say) - post crossed with Refugee while I was typing!

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Old 13th Jun 2018, 12:42 pm   #59
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Default Re: Wiring a desk electric fan.

I ought to just clarify one thing, and that is that once you've established the connections, you don't wire it up with the light bulb permanently in circuit. I just re-read my post above (correcting one blinding spelling mistake!) and thought I'd written it a bit as though I'd hard wired it with the lamp permanently in circuit and it's been like it ever since. No, you DO NOT leave the lamp connected after establishing the correct connections, as it would not only be very inconvenient, but also the motor would run at a very reduced speed.
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Old 13th Jun 2018, 4:22 pm   #60
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Default Re: Wiring a desk electric fan.

Quote:
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Although a relatively simple task for a person with basic radio technology knowledge, I think that rewiring my fan is going to be a bridge too far for me. If anyone resides in the Woodford area of London, maybe I could pay them to locate which wires go where.
We have a section for just this eventuality, if you really feel that this is your best course of action, and your friend is unable to help: https://www.vintage-radio.net/forum/...play.php?f=145
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