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Appliance Controls Repair


									Appliance Controls Repair

Actually, appliance controls aren't household things--they are parts of things. Because they
are parts of dozens of things in your home, knowing how to fix them is vital to fixing many
things you own. For example, nearly all small and large household devices--from table lamps
to heating furnaces--include switches. A few appliances with thermostats include the heating
pad, hair dryer, toaster oven, and crock pot. You'll find timers in the coffee maker, washer,
dryer, dishwasher, and microwave, just to name a few. Knowing how appliance controls

work and how to fix them        earns accolades in the Fix-It Club.

How Do They Work?

Appliance controls are the devices that turn things on and off, regulate temperature, speed,
duration, and otherwise control appliance functions. Appliance controls include switches,
thermostats, rheostats, and timing mechanisms. Some appliances, such as toasters, use
mechanical controls while others, like microwave ovens, use digital controls. Knowing how
they work will help you fix just about any of them.
Appliance switches vary in complexity and functions.
Switches operate by making contact with the conductor of
an electrical circuit. When an appliance is plugged in, it's
connected to an electrical circuit in your home. Power runs
through the wires of the circuit to the appliance. When the
appliance's on-off switch is turned on, electricity flows
through the switch to operate the appliance. There are
several common types of switches: push-button, toggle,
rocker, slide, and throw switch.                                Variable-speed switch from a
                                                                food mixer.
Other appliance controls are also switches. Rheostats,
thermostats, solenoids, and timers, for example, are all types of switches. These components
operate inside appliances to turn on motors, open and close valves, control heating elements,
and turn on different parts of the appliance during different cycles, such as the rinse and spin
cycles of a washing machine. Let's take a closer look at

A thermostat is a switch that controls temperature in a
heating element or a cooling device. It opens and closes a
circuit to furnish current based on temperature. Thermostats
used in appliances may use a bimetal strip, bimetal
thermodiscs, or a gas-filled bellows chamber to control the
electrical contact. If faulty, they should be replaced rather
than repaired.
                                                                 The round device on the right
A rheostat is a variable controller that directs the amount of   is a thermostat inside an
current flowing to many older appliance components. A            electric heater.
blender with a dial control that can be turned to increase or
decrease motor speed uses a rheostat to do so. Because rheostats can be damaged by
moisture, they can easily malfunction.

A timing mechanism controls current flow based on a mechanical or digital timing device
similar to a clock. Timing mechanisms on small appliances usually turn the appliance on or
off. Timers on major appliances--washing machine, dishwasher, dryer, frost-free refrigerator,
or oven, for example--control the various cycles. Mechanical timers on large appliances
consist of a shaft, gears, and a series of notched cams, one for each circuit or cycle. The timer
is powered by a small timer motor. Digital timers are much simpler, using low-voltage
electricity to control various functions such as turning on or off a device. While some timing
mechanisms can be adjusted, those that are faulty should be replaced rather than repaired.

Many of these mechanical controls have been replaced, or at least are assisted, by digital
controls. The good news is that digital controls are relatively trouble free, going many years
without service. The bad news is that when they do go out, there's no repair to do; you simply
buy another unit and plug it in exactly as the old one. Of course, make sure you've solved any
other electrical problems first so the digital controller won't be damaged on installation.

What Can Go Wrong?

What can go wrong with appliance controls? They can quit controlling! Switches won't turn
on and off, thermostats don't properly regulate heat, rheostats don't provide smooth control,
and timers quit timing. In many cases, all that's needed is a good cleaning or reconnecting the
wires. Otherwise, the controller should be replaced rather than repaired.

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