Is anyone familiar with restoring electric motors?

[martin_esq]

I have a Grafonola with the electric motor - the leftmost model here:

and the electric motor has given up the ghost. I suspect it might just need new brushes, but I thought I'd check here - does anyone have experience taking a motor like this apart and restoring it? Does anyone have good sources for spare parts? Thanks!

[Curt A]

The best option is to take it to an electric motor repair shop, if you have one nearby. If they can't fix it, maybe they can diagnose what's wrong. I had a bad motor in a Fairy phonograph lamp, which I took to an electric motor repair shop, even though they didn't have the ability to rewind a 100 yr old motor they were able to tell that it had some bad windings. I had to find a small repair shop that had the time and ability to repair small antique motors. They were able to do it, but it cost $450 to have it fixed. So, with that in mind, you might want to search for a working replacement motor that you could obtain for less money. Mine was specific to the Fairy - no other motor would fit and replacements are non-existent. Since so many Columbias were made, you might get lucky finding one... Good luck with your project.

PS: Maybe someone knows if there are other motors that are interchangeable with the Columbia motors and could be substituted.

[Curt A]

Martin,
I just read a similar post by AllWoundUp regarding brushes in a Columbia motor. His problem might be different from yours, if you have already checked the brushes to see if they are making a contact and it still won't run. Your statement that it has "given up the ghost" is not too enlightening... So, does your motor do anything - spark, smoke, move, make noises, etc.? Also, it is obvious that the power cord has to be in good condition and doesn't have any bare spots to short out (even if it looks good, it should be replaced with a modern cord - cloth wrapped wire cords are available on eBay). The first thing to check is the brushes, which are held against the commutator by a spring - you can stretch them a bit if necessary to make contact. If there is enough tension to hold them in place and your motor still does nothing, it's probably not the brushes... If it is anything else, it is not usually a DIY repair, unless you have worked on electric motors before. Also, because those motors are obsolete, there are no readily available spare parts.

[martin_esq]

Yes, I could have been more specific (sorry):

The motor has worked fine for roughly a year, though with a strong "old motor" smell. This past week though (perhaps under the extra strain from my listening to records while sheltering at home) it started struggling to keep up speed; I flipped the motor plate up and noticed it was sparking intermittently from deep inside the motor. It appears to run fine (except for the sparks) when it's upside down, but when it's right side up it makes a grinding noise and slows to a halt, even without the record platter on the spindle. My guess would be that the sparks and slowing are due to worn brushes, though I'm happy to defer to others' experience? I unscrewed what I expected to be the motor brushes, but found instead what looks like a small strip of leather held in by a spring, coated in some kind of oil.

NB this machine has had any number of other questionable "repairs" done to it prior to moving in with me, so I wouldn't be surprised if the motor had some preexisting issues too.

[stetam]

I have an electric Victor that I cleaned and oiled the motor and moving parts but it runs just a bit slow. Not sure to remedy that.

Steve

[Curt A]

"I flipped the motor plate up and noticed it was sparking intermittently from deep inside the motor."

I'm no expert on electric motors, but the sparking may indicate shorts in the windings, which will cause the motor to lose power. The brushes should not look like oiled leather, they should be solid carbon rectangular pieces held in by a spring... So, you may need to replace those using the instructions in the other thread.

[JerryVan]

The sparking is due to poor commutation. In other words, poor connection between the brushes and the commutator, (the spinning part that the brushes contact). There can be several reasons for this.

1. Brushes worn too short to make firm contact with the commutator.
2. Excessive oil on the brushes/commutator which mix with spent brush carbon to create a black "gunk".
3. Worn armature bearings which cause the armature to wobble around and make the brushes bounce on the commutator, causing intermittent connection.

There are also other factors such as shorts in the armature windings or field coils.

Check out #1, then #2. If the commutator looks completely black it, and the brushes, should be carefully cleaned with a rag soaked in carburetor cleaner, brake cleaner, electrical contact cleaner, alcohol, etc. Don't drench anything, just wipe clean. You could also polish the commutator with some very fine sandpaper. The commutator contacts are made of copper and should be shiny and clean to conduct well. Use caution if you remove the end cap of the motor housing to get at the commutator. There will be wires the go from the inside of the motor, out to the brush holders in the end cap. These wires will be crusty and fragile! Be gentle and aware of how much you're flexing them!

Be aware, some very small degree of sparking is normal.

[JerryVan]

Maybe this will help...

[JerryVan]

Images of a dirty commutator. Even the one that looks not too bad has black gunk between the contact plates. That black gunk is conductive and essentially shorts out the commutator, causing heat and arcing, (sparking).

[JerryVan]

Here's a proper looking commutator...