Sewing Machine Foot Control Pedal

Want look what is inside a foot control of sewing machine? These photos help you do it and to understand how to repair a foot control pedal.
But please be aware that disassembling of any electrical appliances should specialists only.
Modern model of speed controller

In this article I'll show you two types of sewing machine foot control pedals. First type is a modern model of speed controller of computerized sewing machine.
In second half of this post you will see what is inside a foot control pedal of old sewing machines or modern budget models, having oscillating shuttle hook system.

Note: Never open an electrical appliances yourself. This should be done only by specialists. But if you're curious, you can look at what is inside foot control pedal using my photos.

Inside a household foot control pedal you will find not too many details. Usually into the controller case is one rheostat like this.

This is a modern and very reliable type of pedal. But when sewing machine is used for a long time and such pedal can be breaked.
If your sewing machine is running with jerks, that probably the reason is here. On two grafit tracks of resistor plate. They may burnt or worn out.

If you are removed a cover of sewing foot pedal it's desirable to lubricate all internal metal details having friction locations and joints.
Lubricate any joins a pedal with two drops, no more than.

This is connector for joining the pedal to sewing machine.

In this model of sewing machine an electrical power supply cord is connected separately.
Foot control pedal of old sewing machines

Now, you will see what is inside a foot control pedal of old sewing machines or most budget models machines.

This is controller of old model Juki sewing machine made in Japan.

To remove the cover you need unscrew only one screw.

Inside you will to find a ceramic case having the rheostat, but of a different type.

Inside this ceramic block is placed a lot of thin graphite plates. When you press the foot pedal the metal wedge presses down the plate that compresses all graphite wafers into the rheostat together. The more they are compressed to each other the total resistance of the rheostat decreases and an electric motor of sewing machine works at a higher speed.

If you remove the screw and pull of this plate, you can see the rheostat graphite wafers.
Tips: Remove it is needed if a foot controller requires too much pressure to get up to speed, or a sewing machine works only when the pedal is fully depressed or works with jerks.
If the sewing machine has become slower to work, or works with jerks. One of the reasons for this is that the speed controller is faulty.
Graphite plates of foot control rheostat

On this photo shows a device of another sewing foot control pedal, but the graphite plates are identical.

After years of work these plates are burned out or covered by plaques, which prevents good contact between them. In some circumstances you can to repair a pedal if you can remove carbon deposits.
But keep in mind that these graphite circle plates are very fragile. Besides, keep in mind that repairing electrical appliances should be done by specialist only.

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