Rewinding a classic run motor - anyone done it?

[enor]

So, the AV I just bought has both windings of the run motor open. Finding a 230/50 motor isn't all that easy, so I'm thinking - just because I don't know anyone who's tried rewinding one, doesn't have to mean that it's undoable.

Can anyone shed light?

[geoffbrown]

You've started a good thread enor as those of us in 220-250v countries find replacement motors hard to come by.

I recently bought a load of old hammond parts [mostly junk] from a long time hammond enthusiast who claims the run motors windings use a copper wire with a square cross section. therefore making them difficult or impossible to rewind,maybe others on the forum will have more knowledge on this topic?

[enor]

I can't imagine the type of wire being critical, I'm more concerned with how to take the thing apart and getting it back together!

[Roger Memphis]

Speculation for the sake of discussion: To be perfectly candid, I had never opened up a RUN motor. The problem with rewinding a START motor would be getting the bobbin off of the stack of laminations without ruining the laminations... probably hopeless. BUT, if the RUN motor has two coils in there like this drawing, maybe it could be done.
Have any of you curious Hammondites ever torn into a RUN motor? Are the coils removable, so they could be mounted on a mandrel and chucked in a lathe to install new magnet wire?
Cheers !
Roger Memphis

There an operational figure here: http://www.nshos.com/HAMMOND4.htm (Scroll down to third picture).

[enor]

Speculation for the sake of discussion: To be perfectly candid, I had never opened up a RUN motor. The problem with rewinding a START motor would be getting the bobbin off of the stack of laminations without ruining the laminations... probably hopeless. BUT, if the RUN motor has two coils in there like this drawing, maybe it could be done.
Have any of you curious Hammondites ever torn into a RUN motor? Are the coils removable, so they could be mounted on a mandrel and chucked in a lathe to install new magnet wire?
Cheers !
Roger Memphis

There an operational figure here: http://www.nshos.com/HAMMOND4.htm (Scroll down to third picture).

I've never opened one either, but have read various reports about really soft metal in the shaft - so soft it tends to "mushroom" when using a puller to get the pulleys off.

Once inside, it seems easy enough though from the pictures I've seen. The coils appear to slide out with relative ease.

[Roger Memphis]

Just a bit more about what I do know about run motors... They're incredibly tough, long-lived and dependable. They're perfectly happy so sit around for months and months fully energized while locked up... they don't care! :) They pull about the same amps running or locked. When properly lubricated, etc. they run at a constant RPM dependent upon the frequency (not voltage) of the input. The primary reason for their coils to fail would be over-voltage... i.e. feeding 220 v to a 120 v motor. Or perhaps some severe mechanical abuse has broken the connections (which would more likely be repairable). Magnus, since you have a dead one, how about opening it up and take a look?... maybe even post us some pictures.
:)
Roger Memphis

[johwin61]

Magnus, did you get any further on this motor?

[freiburg]

I've never opened one either, but have read various reports about really soft metal in the shaft - so soft it tends to "mushroom" when using a puller to get the pulleys off.

Once inside, it seems easy enough though from the pictures I've seen. The coils appear to slide out with relative ease.

I did it more than once....



Christian

- - - Updated - - -

The primary reason for their coils to fail would be over-voltage... i.e. feeding 220 v to a 120 v motor.

The primary reason for failing on every motor I repaired up to now was the junction of the thin wire used for the coil and the thick wire leaving the coil.


I really would love to have a decent winding machine to produce replacement coils, I haven't..... unfortunately.

Christian

- - - Updated - - -

I can't imagine the type of wire being critical, I'm more concerned with how to take the thing apart and getting it back together!

It is critical for various reasons:

1) The geometry, there is not much space
2) The DC resistance
3) The AC resistance

Christian

PS: To answer finally the inital question (anyone done it): Yes, see picture above: the right coil is a new one. Made by some talented Swiss guy who made a batch of coils for our master Hammond Tech in Switzerland. I got this one from him. It is my only replacement coil. Unfortunately I don't know, who made these coils. And there are only about 2 or 3 coils left. The left one btw is one I repaired.

[alpine]

I did it more than once....

The primary reason for failing on every motor I repaired up to now was the junction of the thin wire used for the coil and the thick wire leaving the coil.

Fortunately on mine, the run motor is OK at present, but this is a useful thread. For your repairs, Christian, were you just able to re-solder the joint or did you have to attempt a rewind? Or was it a welded joint?

[freiburg]

Well, this is a procedure that I did twice and I was succesful in both cases. But my feeling is, that the rate of success would not be 100% in the long term. It is very difficult and very delicate.

You have to unpeel all protective layers of the coil and then you have to unwind the wire back to a stable region, then you have to get rid of the insulation layer, which I couldn't burn away without burning the wire, so you have to scrape it away.

Then you you solder a new wire to it and then you have to reassemble it.

Christian

[alpine]

Well, this is a procedure that I did twice and I was succesful in both cases. But my feeling is, that the rate of success would not be 100% in the long term. It is very difficult and very delicate.

You have to unpeel all protective layers of the coil and then you have to unwind the wire back to a stable region, then you have to get rid of the insulation layer, which I couldn't burn away without burning the wire, so you have to scrape it away.

Then you you solder a new wire to it and then you have to reassemble it.

Christian

Thanks! Sounds nasty. I suppose an alternative if it happened is to get one of the more common 110volt ones and use one of the little up/down transformers in the line. The current demands are not high. Ebay seem to have some for about £9.

[freiburg]

That does not work!! The motor, the scanner, the generator, this all is 50 Hz stuff. You cannot mix with 60Hz components!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[alpine]

That does not work!! The motor, the scanner, the generator, this all is 50 Hz stuff. You cannot mix with 60Hz components!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

True! Post Christmas brain fade! But you could take the coils out of a 60Hz one presumably and put them in the duff 50Hz one unless the armature dimensions are different.

[freiburg]

No you can't, they are electrically different. You can see this already on the DC resistance readings which differ. Both motors have about the same wattage but differ in voltage by a factor of 2. So the impedance has to be different. I am not an engineer.... but P=U^2/Z - more or less....

There are also mechanical differences: the 60Hz motor uses a 6 pole armature, the 50 Hz motor a 4 pole armature. the rpm are different and the scanner gear is different. apart from this and of course the coils, they are the same. the geometrical dimensions af the coils are also the same.

[alpine]

No you can't, they are electrically different. You can see this already on the DC resistance readings which differ. Both motors have about the same wattage but differ in voltage by a factor of 2. So the impedance has to be different. I am not an engineer.... but P=U^2/Z - more or less....

There are also mechanical differences: the 60Hz motor uses a 6 pole armature, the 50 Hz motor a 4 pole armature. the rpm are different and the scanner gear is different. apart from this and of course the coils, they are the same. the geometrical dimensions af the coils are also the same.

Are the armatures the same diameter?