Rewiring a SM Motor

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by , 04-18-2012 at 07:55 AM (1192 Views)
Quote Originally Posted by J Miller View Post
Quote Originally Posted by sew wishful View Post
My friend just purchased her first vintage machine...a Universal Japanese clone. Serial #Z77218 Can someone give a date? She plugged it in last night and sparks flew!! She asked me to look at it. Bare wires coming out of the motor and then black tape to the plug in end to the machine case, about 8 inches long. I've never done any motor rewiring. Is there a tutorial for this, or do I need a more experienced person to work on it? Any help would be deeply appreciated!
sew wishful,

Easy way: Go to Sew-Classic { http://shop.sew-classic.com/ } and buy a replacement motor with bracket. It will bolt right on and plug right into the cord block.

Less easy way:

Go to a hardware store and buy some 18 ga SPT-1 wireing. If you get the SPT-2 you might have trouble fitting the wire through the motor. The SPT-1 or 2 refers to the thickness of the insulation. For a better tutorial on it, go to Sew-Classic and go to the section for bulk wire. She has a lot of information in there.

>Take the motor off of the machine, remove the bracket and pulley.
There will be a way to separate the motor halfs. Either screws from the outside going into a bracket or a long bolt with nuts on it or ????. You just have to look for them.
>Before you split the motor, remove the brush caps and the springs and brushes.
>Then since the wire is already bad, cut it off just outside the motor housing.
>Then split the housing and carefully take it apart.

>Once apart you'll find the main shaft with the commutator (where the brushes contact the armature) possibly some little thrust washers and lots of crud.

>Also follow the old wires to where they are soldered onto the outer wirings. These have to be un-soldered and the new wires soldered on.
That is the hardest part to this job.

>The second hardest part is cleaning the motor of all the crud.
> Clean the glaze off of the commutator, I use 600 grit sandpaper wrapped around a popsicle stick. I don't cut into the copper, I just clean it.
Clean the brush areas, make sure the springs are good. Clean the caps. They are probably Bakelite so will be fragile and brittle.

Now, once it's cleaned inside and out, and the new wires are soldered in you have to reassemble it.
The armature goes in first, one way or the other. Then depending on which end of the case the wires come out of you have to guide them out through the hole. Now, usually there is a knot tied in the wire to prevent it from being yanked out and damaging the connections inside. I'm horrible with knots but I do it as small as I can. If your lucky there might be a stress relief part passing through the hole around the wire. If that is there you'll see it when you're taking apart. Just put it back in the way it came out.
Finish assembling the motor making sure the wires don't get in the way of the armature on the insides and the brushes line up too.

The motor will need some oil so do that too. Don't flood it though.

Put the plug on it and plug it in. If you've done it right, it will run just fine. If not, well try again or refer to the easy way above.

This is basically what I do. I hope I haven't been to vague.

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  1. DonnaQuilts's Avatar
    New parts/wiring can be obtained from sew-classic.com.
    Jennie at sew-classic can give you help and advise further.
    I have parts ordered, order number 3, for parts, for my daughters FW, right now. I bought the most wonderful foot controller from them and glad of it. Have them wire any foot controller for a small charge. It is well worth it.
    Sewing machines can cause bad shocks if the frame is electrified. You are lucky it was only sparks. A grounded receptacle is always good.
    Have you ever felt a slight vibratory feeling in your sewing machine while plugged in and not sewing. That is stray voltage. My 201-2 has it and DH can't feel it. He's an electrician and I can't get him to acknowlege this is happening. Had a lamp like that once and it turned into a "shocker". Good luck with the machine.
  2. DonnaQuilts's Avatar
    Sorry the link didn't work. I got it from QB. I save the interesting ones to a word document. Anyway just try Sew-Classic.com and it should go. They are located in Ohio and ship quickly. That's why we use them. The good prices don't hurt either.

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