Weak magnet?

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RSR Engineer
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Weak magnet?

#1

Post by RSR Engineer » Wed Apr 10, 2019 11:33 pm

A friend of mine recently gave me a loco that he said he wanted to see go to a good home. She's an H0 gauge Japanese brass model of about 1965-1970 vintage. Evidently she hasn't turned a wheel in years and her performance is a bit quirky. Before testing her I gave a 10,000 mile service - oiling round, commutator cleaning etc. On starting I find she draws anything between 0.6 and 1.7 amps. This goes down to 0.4 - 0.7 once she gets rolling. Also, the loco is at first very slow, even on full voltage. Starting with the load simulator pushes the amps to 2.0, which blows the breaker. The loco is very sensitive to a 1 in 68 gradient, being faster downhill than up. The wheels turn perfectly evenly - no sign of binding. All these things lead me to suspect that the magnet in the motor may have lost some (or perhaps much) of its strength. Can anyone please confirm (or contradict) this theory? I'd be grateful for any help I can get on this.

There's a picture on flickr: https://www.flickr.com/photos/53775591@ ... 783700505/

Cheers and many thanks,
Artur

Mountain Goat
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Re: Weak magnet?

#2

Post by Mountain Goat » Thu Apr 18, 2019 7:38 pm

Two possibilities here. One is a weak magnet and the other is a little oil on the commutator plates. However, with oil the symptoms I have had are plenty of speed at first and then it slows as the oil dries, and then some smoke with slow running and then the controller trips.
A weak magnet tends to be weak and I have had the overload trip which indicates a high current draw or a short circuit. I believe it is a weak magnet, which usually happen on models around 40 years of age or older.
Enjoying freelance modelling in 7mm narrow gauge Feel free to ask questions relating to the Mountain Goats Waggon & Carriage Works thread.

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Re: Weak magnet?

#3

Post by RSR Engineer » Tue Apr 23, 2019 6:24 pm

Thank you, MG, you've confirmed my suspicions. I suppose I could acquire a couple of small neodymium magnets and mount them alongside the main one. Perhaps you or another member can advise me on what strength they should be how to orient them and hold them in place?

Cheers and many thanks,
Artur

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Re: Weak magnet?

#4

Post by footplate1947 » Tue Apr 23, 2019 9:15 pm

Have a look on ebay, a few sellers......... One reliable seller I have bought a lot of spares from is john050272
He sell a lot of Hornby spares. He has most Neo Mags ........ And his prices are reasonable....................John
If only there was enough hours in the day..................John

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Re: Weak magnet?

#5

Post by RSR Engineer » Tue Apr 23, 2019 11:07 pm

Many thanks, John, I'll follow that up.

Cheers,
Artur

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Re: Weak magnet?

#6

Post by footplate1947 » Wed Apr 24, 2019 7:42 am

I only suggested him because he is in the business of spare magnets and he may know about the motor in your loco. One thing which may help is taking the body off the loco and let us have a look at the motor which is in this loco also you will be able to see any identifying marks or numbers or makers names on the motor concerned.
If only there was enough hours in the day..................John

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Re: Weak magnet?

#7

Post by Mountain Goat » Wed Apr 24, 2019 9:53 am

You can get motors remagnetized. Someone on here or on another site (I don't remember who it was) was making a remagnetizing device and offered to sell me one, but though I would have absolutely loved to buy it, I just didn't have the funds at the time. It is a tool that would be very rarely used but so useful. Whoever it was, if you read this, let us know who you are. Mind you, as I speak I still don't have the funds... Sometimes I do and other times I don't... :lol:
Enjoying freelance modelling in 7mm narrow gauge Feel free to ask questions relating to the Mountain Goats Waggon & Carriage Works thread.

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yelrow
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Re: Weak magnet?

#8

Post by yelrow » Wed Apr 24, 2019 10:37 am

Ronald Dodd, is your man. Look at his website. Also, at his massive Hornby Dublo, 3 rail layout. john

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Re: Weak magnet?

#9

Post by footplate1947 » Wed Apr 24, 2019 10:40 am

Hello MG yes I know you can re-mag magnets in the old Hornby XO 3/4s ect; but I think the new can type motors are not easy to work on and I class them as sealed units. I had trouble with the well known problem motor in the Hornby Rail Road Scotsman, Tornado locos. I had the motor apart and cleaned the commutator and brushes and it looked fine but still gave trouble after reassembly. The only cure I found was to find a motor which fitted and replace it. You can normally find something which fits if you look around.
I have found one supplier who still has most of the Hornby Bachman and other makes of spares which all the others dealers have run out of stock of.. Very handy. WTD found a replacement motor for an Scotsman for me only the other day. That was handy.
....................john
Last edited by footplate1947 on Wed Apr 24, 2019 11:02 am, edited 2 times in total.
If only there was enough hours in the day..................John

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Re: Weak magnet?

#10

Post by teedoubleudee » Wed Apr 24, 2019 10:47 am

yelrow wrote:
Wed Apr 24, 2019 10:37 am
Ronald Dodd, is your man. Look at his website. Also, at his massive Hornby Dublo, 3 rail layout. john
https://www.youtube.com/watch?v=yyyPKCHa0gQ

https://www.youtube.com/watch?v=DMBjn0LvCjU
Most people are shocked when they find out how bad I am as an electrician

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