This will be my next to last post in my Singer restoration series, because I’m almost finished! Last night I repaired all the electrical components, with a lot of help from my husband Matt. If you haven’t yet read the other posts here is part 1, part 2, part 3 and part 4.
My machine’s wiring was in terrible shape. When I first plugged in the machine the foot pedal wasn’t controlling the motor, the motor was running off and on, but the light worked. The first thing I did was dismantle the electrical system, the 15-90 is unique because the electrical system is removable, here is the diagram of the electrical components on the 15-90:
Once off the machine I inspected the wiring. Basically the motor and light had crumbling insulation, which meant exposed wires, and the foot pedal’s ring connector wasn’t attached anymore. You can see all the damage best on this picture of the 3 pin terminal:
Supplies for repair:
To re-cover the exposed wires we used heat shrink, which is plastic tubing you can cut to size and shrinks tight when heat is applied. Technically you are suppose to use a heat gun, but a lighter works just fine. We started with the motor, here it is before:
One side was completely exposed, the other had crumbly old insulation still intact. I stripped away the old insulation down to about an inch from the motor.
Matt then covered the wires in electrical tape, then heat shrink tubing and applied heat.
Here is the completed repair to the motor:
We followed the same procedure for the light’s wiring:
The foot pedal repair was a bit more complicated, here is the wiring before:
I stripped the old insulation down an inch or so and Matt clamped on a new ring connector. We tried at first to re-use the old ring connector, but the wires were soldered/melted into it. So in the middle of the project Matt ran to Wal-Mart to buy clamp on ring connectors. If you need to use new ring connectors use the 3 pin terminal to determine the correct size. You could also solder the old wiring back together.
At the other end of the foot pedal the connections were solid, but there was a little wire poking out, which I covered with a small piece of heat shrink.
To finish I re-connected all the ring connectors on to the 3 pin terminal, here is a technical drawing of the correct order from the 15-91 adjustments manual:
Pin 1(yellow): foot pedal and light fixture. Pin 2(black): foot pedal and motor. Pin 3(red): motor and light fixture
We plugged the power cord in and everything worked, light came on no problem and the foot pedal once again controlled the motor! I put the whole electrical system back on my machine, and it looked great. I need to order a new drive belt before I can test its sewing abilities but I don’t foresee any problems.
This machine has come a long way from the thrift store trash it was before. In my next post I will be purchasing a new drive belt and doing some sewing with my completely restored machine.
Having problems with your own vintage Singer? I’m no expert but I would love to help you puzzle out your problem just leave me a comment.
UPDATE: How to Clean & Restore Vintage Singer Sewing Machines the eBook is now available in the Zounds Shop! Save and print all of the information you need to fix your machine!