Large and small appliances accomplish a great deal by putting a few basic electrical and mechanical concepts to work. You can begin to understand how most appliances operate if you master those concepts— they’re explained in this section. The General troubleshooting notes concluding this section describe common problems that most electrical and mechanical devices fall prey to.
Electrical repairs are a large part of appliance servicing, so be sure to review the basics of working with wires, plugs and motors. You’ll find that an inexpensive device called a volt-ohm meter is an invaluable tool for troubleshooting. Even minor electrical repairs can be hazardous if not done correctly, however. “For You Safety” tips are found throughout the section.
Main topics include:
Tools and supplies
Many of the tools required for electrical work and appliance repair, including screwdrivers, wrenches, pliers, and a utility knife or jackknife, are probably already part of your home tool kit. In addition, you will need special tools for working with wire and for soldering. These tools, as well as the electrical testers shown on the facing page and the supplies described at right, are readily available at most hardware stores and home centers.
Buying tools. To minimize costs, purchase special tools only as needed. (An exception is the volt-ohm meter, an invaluable and moderately priced device that will quickly repay your investment.) A quality tool may cost more, but it will last longer and be safer to work with. Tools used for electrical and appliance repairs should have fully insulated handles in good condition to minimize shock hazard if you accidentally touch a live circuit with the tool.
Rubber grips (shown on the screwdrivers below) help you hold a tool more securely and comfortably.
TIPS FROM THE PROS: Make a screwdriver more useful by running a magnet along its shank several times in one direction. A magnetized screwdriver will help you to start small screws and to retrieve screws that fall inside the appliance as you work.
Tools for appliance repairs:
Basic supplies (shown above) :
A volt-ohm meter (VOM) is the most Important and versatile electrical tester you can own. (A lull description of the meter is given below.) A neon test light and a voltage probe (u power pen) are inexpensive tools that tell you at a glance whether or not you've turned off the power to a circuit. You must have this critical information before you make any electrical repair. CAUTION: Never work on a circuit or an appliance unless you know for sure that the power has been disconnected.
A continuity tester is used to find open and short circuits. Such tests often require the use of jumper wire, which you can buy at a hardware store or make yourself (see bottom right).
Volt-ohm meter measures voltage and resistance, and tests for continuity and grounding. Digital VOM's are easier to use and more accurate than analog models.
Voltage probe does the same job as a neon " light (top right) but is safer and more convenient to use.
Neon test light glows when voltage is present. If you buy one, make sure it’s rated for 120 to 240 volts.
Continuity tester is a small flashlight that lights up when its probe and clip are connected to make a complete circuit. Use this tester only with the power off.
Plug-in outlet analyzer can diagnose reverse polarity, a bad grounding connection, and other wiring faults.
----- Underwriters Laboratories (UL) is an independent, not-for-profit product safety testing and certification organization. UL evaluates a wide range of products, including electrical tools, appliances, devices, and supplies, forfire, electrical, and related safety risks. An Underwriters Laboratories label or stamp on a product means that samples of the product have been found to conform to nationally recognized safety standards. Look for the UL mark whenever you buy electrical equipment. ------
Using voltage testers:
Using a neon test light to verify that power to a receptacle is off requires caution. Keeping fingers away from probe tips, insert tester probes into both slots of an outlet. If power is off, tester won't light up. Be sure to test both outlets.
A voltage probe need not be inserted into a receptacle. Simply hold the probe close to each slot. It voltage is present in receptacle, probe will light up and/or emit an audible tone. The probe can also detect voltage within appliances.
Using a continuity tester: To test a plug-type fuse, attach tester clip to fuse contact; touch probe to fuse threads. To test a cartridge fuse, touch tester clip to one end of fuse and tester probe to the other end. In both cases, tester light will glow if fuse is good.
To test an extension cord, attach tester clip to one flat prong on the plug, and insert the probe in the corresponding hole as shown. Tester light won’t glow if there are breaks in the conductor. Repeat the procedure on the other prong.
How to make a jumper wire:
1. Jumper wire can be purchased in a hardware store, but it's also easy to make. Take a 2- to 3-ft. length of insulated No.18 wire and strip ½ in. of insulation from both ends.
2. Slip insulating sleeves past the ends of the wire, crimp alligator clips to the bare wires, and slide sleeves over the clips. Make sure that sleeves completely cover bare wire.
The flow of electricity through a wire is often compared to the flow of water through a pipe. Although the analogy is hardly precise, it's useful in describing a force that intimidates many people. Electricity is basically the flow of subatomic particles called electrons through a conductor (a material whose resistance to electrical flow is low; cop per wire is one example). Materials, such as plastic or rubber, that offer high resistance to electrical flow are called insulators. Electricity can be described by its rate of flow, or current, measured in amperes; by the pressure that forces it to move through a conductor, measured in volts; and by its power, or ability to do work, measured in watts. Resistance to electrical flow is measured in ohms.
AC/DC. Household electricity is produced by power plants as alternating current (AC), which reverses direction 120 times per second (60 cycles" per second) as it flows through circuits. Batteries supply direct current (DC), which flows in one direction only. AC power must be converted into DC power in order to charge batteries.
In the United States, electric current is delivered to homes and offices at 120 and 240 volts. Light fixtures and small appliances operate on 120 volts; heavy- duty electrical appliances use 240 volts. (In other countries, standard voltages may differ.) The wattage of any electrical device-the amount of power it uses-is determined by multiplying volts by amperes (see box below). For example, an air conditioner that draws 5 amps at 120 volts consumes 600 watts of electricity (5 x 120 = 600). If you run the air conditioner for an hour, it will consume 600 watt-hours worth of electricity. If you use 1,000 watts for an hour, you've consumed 1,000 watt-hours (1 kilowatt-hour). Your electric bill is based on kilowatt-hours, determined by the total wattage of all your lights and appliances and the length of time they are in use.
Electric circuits. To light a bulb or run a washer, electricity must flow in a circuit, a closed loop formed b conductors that lead from a power source to a load" (a power-using device) and back to the source. An on-off switch may be located between the source and the load. The power cable for a typical residential electric circuit contains three conductors-usually copper wire- wrapped in plastic or rubber insulation. One or two hot conductors, usually sheathed in black or red insulation, each carry current at 120 volts from the main service panel to a load. A white- coded neutral conductor carries current at zero volts from the load back to the service panel. A bare or green-coded grounding wire provides a safe path to earth for abnormal current flow anywhere along the circuit.
Grounding. In a properly grounded electrical system, an uninterrupted grounding path links all receptacles, switches, and metal outlet boxes to the ground/neutral bus bar in the main ser vice panel. The main ground wire connects the bus bar to a plumbing pipe and to a metal rod driven into the ground just outside the house. Because current follows the path of least resistance and copper wire offers less resistance than your body does, grounding ensures that abnormal current will flow into the ground, not through you.
AMPS = volts ohms
VOLTS = watts ÷ amps
WATTS=volts x amps
OHMS = volts ÷ amps
!! FOR YOUR SAFETY !!!
!!! Most electrical accidents are caused by carelessness or ignorance. If you combine a basic knowledge of electricity, a healthy respect for it, and a dose of common sense, you can safely tackle many household electrical repairs. Here are some basic guidelines for working with electricity:
Before working on a circuit, go to the main service panel and remove the fuse or trip the breaker that controls that circuit (see facing page). Tape a sign to the panel warning others to leave the circuit alone while you work.
Before touching any wire, use a voltage tester to make sure it's not live.
Whenever you check for voltage in a receptacle, check both outlets-each may be con trolled by a separate wiring circuit.
Never stand on a wet or damp floor when working around electricity. Cover the floor with rubber mats or dry boards.
When replacing fuses, turn off the main power first. Make sure your hands and feet are dry, and place one hand behind your back to prevent electricity from making a complete circuit through your chest, Touch a plug fuse only by its insulated rim. Remove cartridge fuses with a fuse puller.
Use tools with insulated handles and ladders made of wood or fiberglass.
To protect children, place safety covers over any unused outlets.
When unplugging a power tool or appliance, pull on the plug, not on the power cord.
Improperly used extension cords are a leading cause of electrical fires. They are for temporary use only--do not use them to extend a circuit permanently.
Keep dry, chemical fire extinguishers in the kitchen, basement, and workshop.
Never disable grounding devices. Make sure that all appliances requiring grounding are properly grounded, and that the electrical system itself is properly grounded.
Meet or exceed all building code requirements that cover the work you are doing.
Always work with enough light to see what you are doing; it's easy to make mistakes when you're working in dim light.
When in doubt about the safety of any electrical repair or test, call in a professional.
[hot wire; Service panel; Switch closed; Power company; Neutral wire; Ground; Grounding wire ]
Electricity in the home
Electricity enters the home through the main service panel, where it’s divided into branch circuits, each protected by a fuse (in old houses) or circuit breaker (in newer ones). Each branch circuit extends from the service panel to a particular area of the house, supplying power to lights and receptacles. The amperage rating of a fuse or breaker is matched to that of the circuit it protects. If a circuit draws more current than it can handle, its circuit breaker trips or a metal strip in its fuse melts and breaks, thereby cutting off current flow and preventing a fire. Unlike circuit breakers, which can be reset after they trip, a blown fuse must be re placed. Never replace a blown fuse (or a defective breaker) with one rated for higher amperage, and never reactivate a circuit until you've identified and corrected the cause of the problem.
There are three types of branch circuits. Lighting circuits are 120-volt, 15- or 20-amp circuits that power all light fixtures and most receptacles in a house. Small-appliance circuits are 120- volt, 20-amp circuits that supply receptacles in the kitchen, laundry, and home workshop (more amperage accommodates the many electrical devices used in these areas). Individual appliance circuits supply ranges, dryers, and other major appliances. They can be either 120- or 240-volt and range from 20 to 50 amps. How much current a circuit can handle depends on its wire gauge. Most 120-volt circuits contain 14- or 12- gauge solid copper wire. Most 240-volt circuits use 12- or 10-gauge wire. For more on wire gauges, see below.
Turning off the power:
To cut power throughout the house, trip the main breaker at the service panel; if you have a fuse box instead of a breaker panel, remove the main pull out block or turn the lever switch to Off .To cut power to a circuit, trip the breaker or remove the fuse that controls it (see For your safety).
Correcting circuit overloads:
Overloaded circuits are the most common cause of blown fuses or tripped breakers. The easiest way to eliminate an overload is to reduce the number of appliances on the circuit. But to do so you need to find out which fixtures and receptacles are involved. First turn off the affected breaker (or remove the fuse). Then walk through the house, flipping switches and checking receptacles with a voltage tester or with a lamp that you know works. Fixtures and receptacles on the problem circuit are the ones that are inactive. (Remember that circuits may extend into adjoining rooms and other floors.) Next add up the wattages of all the lights and appliances on the circuit. (If an appliance is rated in amperes only, multiply the rating by 120 volts to get its wattage.) If the total wattage on a 15-amp circuit exceeds 1,800, the circuit is overloaded; the limit for a 20-amp circuit is 2,400 watts.
Move some appliances to another circuit and restore power to the inactivated circuit. If the circuit still fails, the cause may be a faulty breaker or a short circuit in a lamp, appliance, or the house wiring. For more on short circuits and other circuit faults, see below.
Circuit breakers and fuses
Knife-blade cartridge fuse (up to 600-amp)
Ferrule-type cartridge fuse (up to 60-amp)
Single- pole circuit breaker (15- to 30-amp)
Plug fuse (15- to 30-amp)
Black or red for hot (live) wires.
White for neutral wires.
White wire recoded black (with paint or tape) is hot.
Green or bare copper for grounding wires.
Overcurrent protection devices turn off circuits that draw too much current. Reset a tripped breaker by flipping it first to Off or Reset, then to On (some can be flipped directly to On.) To replace a fuse, follow safety precautions on facing page. A cartridge fuse may show no sign of having blown, and a plug fuse can be blown even if its link appears to be OK; check either one with a continuity tester or a VOM.
Electrical codes: Your home's electrical system should meet or surpass the minimum safety standards set in the National Electrical Code (NEC). Published and updated every 3 years by the National Fire Protection Association, the NEC serves as the model for state and local codes. Before repairing or adding to a household electrical sys tem, call your local building inspector for up-to-date code information. Make sure you adhere to local building codes, which may be more stringent than the NEC.
If a circuit that is not overloaded fails repeatedly, the problem is probably a short circuit in the house wiring or in a lamp or appliance plugged into the circuit. A short occurs when a hot wire whose insulation has worn down touches a bare patch on a neutral wire or (in the case of 240-volt circuits) on another hot wire. A short may also occur in the windings of a motor. When a worn hot wire touches the metal cabinet of a grounded appliance (i.e., one with a three-prong plug), the condition is called a short to ground. Either way, the result is the creation of an abnormal low-resistance path for a large amount of current. Although the current surge wilt quickly trip a breaker or blow a fuse, it can also create sparks and start a fire-which is why it's crucial that you locate and cure a short before restoring power to the circuit.
To determine whether a short is in the house wiring or in an appliance or fixture, unplug all electrical devices from the affected circuit and look for damaged plugs or cords-a common cause of shorts-and repair or replace them. With the devices still unplugged, restore power to the circuit. If it fails right away, the short is in the house wiring, call in an electrician. If the circuit fails only when you plug in and turn on a lamp or appliance, the short is in that device; repair it or replace it.
A ground fault is an abnormal electric current that's large enough to be felt but not large enough to trip a circuit breaker or blow a fuse. Such faults usually occur when a loose or worn hot wire touches an ungrounded metal outlet box or the metal housing of an ungrounded appliance. Because the metal isn't connected to ground, very little current flows-until you touch it and provide the missing ground connection. The resulting current surge may not be large enough to trip a breaker or blow a fuse, but it can be fatal. To protect against ground faults, install a ground fault circuit interrupter wherever water and electricity could come together (see “For your safety” below).
Open and partial circuits:
If an appliance fails to work when you plug it into a live receptacle (see General troubleshooting), suspect an open circuit-a broken wire or connection--in the power cord or in the plug. To do its work, electricity must travel in an uninterrupted circuit. If
A nicked or partially severed wire won't stop cur rent flow but will impede it, causing a light to flicker or an appliance to run poorly. The increased resistance can overheat a wire and melt its insulation; that can lead to a short circuit or ground fault.
FOR YOUR SAFETY:
Guarding against shock and fire:
Circuit breakers or fuses and a proper grounding system are your home's main defenses against electrical hazards. Grounded and polarized receptacles are an integral part of this defense. The half-round slot in a grounded receptacle (see facing page) extends grounding protection to tools and appliances with three-prong plugs-as long as the grounding prong on the plug is intact. In a polarized receptacle, the longer vertical slot is connected to the neutral circuit wire, while the shorter slot is hot. The difference in slot sizes prevents you from inserting a polarized plug (whose neutral prong is wider than the hot prong) the wrong way and possibly creating a short. You can test the receptacle for grounding and wrong- way polarity with a volt-ohm meter or with an outlet analyzer.
Ground fault circuit interrupters are another important part of your home's electrical safety system. Required by the National Electrical Code in all new bathrooms, kitchens, laundries, and for outdoor receptacles, and highly recommended wherever water and current can come together, a GFCI acts as a supersensitive Circuit breaker. There are three types of GFCI's. A GFCI breaker replaces a standard circuit breaker in the main service panel and protects every receptacle on that circuit. A GFCI receptacle replaces a standard receptacle and, depending on how it's wired (see below), can protect all downstream receptacles. A portable GFCI can be plugged into any outlet but will protect only those tools and appliances plugged into it. By pressing the test button on a GFCI, you can make sure the device is working properly. Test a GFCI monthly; if it fails, replace it immediately.
Receptacles and switches
The 120-volt receptacle:
A standard 120-volt, 15- or 20-amp duplex receptacle, which can take two plugs at the same time, has Iwo silver-colored screw terminals, to which neutral wires attach, two brass-colored terminals, to which hot wires attach, and a green grounding screw (newer receptacles may have neutral and hot push-in terminals as well). Break-off tabs between the sockets allow you to wire a receptacle so that one socket is always live while the other is switch-controlled.
Neutral slot (long) Ground slot (rounded) Neutral [ terminals Grounding terminal ; Mounting yoke, Hot slot (short), Hot terminal, Break-oft separator tab, Hot terminal, Mounting screw; Strip gauge, Release slot, Push-in - wire terminal
Receptacles don't often fail, but cases can crack, dirty slots can prevent contact between receptacle and plug, and an appliance short can burn out a receptacle. Whatever the problem, always replace a defective receptacle with one of the same amperage and voltage rating. Replace ungrounded two-slot receptacles with grounded three-slot models-but only if the outlet box is grounded or if the house wiring includes a separate grounding wire.
Appliances that use 240-volt service require special outlets and mating plugs to prevent other appliances from being plugged into that circuit. Three of the most common configurations are shown below.
Replacing a receptacle:
Before working on a receptacle, cut off power to it at the service panel, then use a neon test light or a power pen to make sure the receptacle is not live. Remove the cover plate and loosen the mounting screws. Pull out and remove the old receptacle. Connect circuit wires to the new receptacle: hot wires (black) to brass screws, neutral wires (white) to silver screws, and the ground wire to the green screw.
Mid-circuit receptacle is connected to incoming and outgoing circuit wires. Some codes require that mid-circuit receptacles be joined to circuit wires by means of short lengths of wires called pig- tails. A wire connector joins the pigtail to incoming and outgoing circuit wires. This way, a problem in one receptacle won't interrupt continuity in the rest of the circuit. End-of-circuit receptacle at left is connected directly to incoming circuit wires. For more on wiring connections, see below.
Testing and replacing wall switches:
The common single-pole switch controls a light or receptacle from one location. It has two brass-colored terminals, to which only hot wires attach, and On/Off settings are marked on its toggle (newer models may also have push-in terminals and a grounding screw). Three-way switches, with two brass and one dark terminal, control a light from two locations. A 4-way switch, with four brass terminals, is used with two 3- way switches to control a light from three locations. (Three- and 4-way switch toggles are not marked On/Off) A simple continuity test (Step 2, below) can tell you if a single-pole switch is defective. Always replace a switch with one of the same type and of the same voltage and amperage ratings as the original.
1. Turn off power to switch at service panel. Remove cover plate, and use a neon test light or power pen to make sure power is off. Place a probe on metal box (or on bare grounding wire if box is plastic); touch each switch terminal with second probe. Tester shouldn't light at all.
2. Once you're sure circuit is dead, disconnect old switch and test it for continuity. Set clip of continuity tester on one terminal; touch probe to the other terminal. Flip switch on and off. Tester should light only when switch is on. If the switch is faulty, replace it.
3. Switches are connected to hot wires, never to neutral. A mid-circuit switch (shown) is connected to two black wires. In a switch loop, in which only one cable enters box, switch is connected to a black wire and to a white wire recoded black; in this case, white wire is also hot.
Using a volt-ohm meter (aka DMM, digital multi-meter)
Display. A digital readout panel displays reading and, in many models, the selected function and range. Some models also have a beeper or buzzer to make continuity test results audible.
Meter body or housing should be sturdy and shock-resistant.
On-off switch activates: the meter. Many meters have an “auto-off” feature to save batteries.
Selector switch determines the function to be measured. Autoranging models like the one shown here automatically set proper range. On other VOM’s range must be set manually.
Jacks connect each test probe to the meter. Normally the red probe is plugged into the “+“ jack and the black probe is plugged into the “-“ jack.
Metal probes on test leads are used to touch various components in a circuit. Insulating sleeves keep user from contacting a live electrical circuit.
A multitester, or volt-ohm meter is a simple, inexpensive electrical tester that is well worth acquiring if you plan to do appliance or other electrical repairs. In addition to testing a circuit for continuity, the VOM measures the actual amount of resistance in a circuit (ohms) and the strength of the electrical force passing through a circuit (volts); some models also mea sure the amount of current (in milli amps) passing through a circuit.
How it works. When you touch its probes to a circuit, the VOM samples resistance, voltage, or current and displays its findings on a digital readout or an analog scale. Knobs or buttons on the meter allow you to select the specific test you wish to make as well as the proper range for the item you’re testing. For ohms readings, a battery inside the VOM passes a tiny current through the component being tested to gauge the amount of resistance in the circuit. Because the current is battery- supplied, ohms tests are done on unplugged appliances. Voltage tests, either AC or DC, involve live circuits and must be done very carefully (see For your safety).
Buying a VOM. Electrical and radio supply stores carry a wide variety of volt-ohm meters. The cost of a VOM is usually in direct proportion to its accuracy. Digital meters are generally more expensive than analog, but they are also more accurate and easier to use. Autoranging meters automatically establish the proper range. Buy a meter that has a fuse or circuit breaker to protect itself against electrical surges or improper hookup.
The tests on the facing page feature an autoranging digital VOM; other VOM’s may differ. Read the manual that comes with your VOM, and practice the test procedures.
Display. To read VOM, note needle’s position on selected function scale.
Calibration screw adjusts needle to compensate for inaccuracy caused by temperature changes or shock.
Zero ohms dial must be adjusted before an ohms test.
To “zero” a VOM, select de sired range. Touch probes together and turn dial until needle hits zero exactly.
Selector switch may have more range settings than digital version.
Alligator clips attached to VOM probes grip component being tested so you can adjust meter or manipulate wires in ohms tests. Clips also keep hands away from live connections in voltage tests.
Testing for continuity---A continuity test determines if a complete circuit exists within an appliance. Select the ohms function and lowest range, usually RX1, on the VOM. (‘Zero” an analog meter as described on facing page.) With the appliance unplugged but its switch turned on, touch meter probes to the flat prongs of a grounded plug (or to both prongs of an ungrounded plug). Meter will read near zero ohms if circuit is complete. A high reading indicates that the circuit is open and must be repaired.
Testing for AC voltage---A volt-ohm meter not only detects the presence of AC voltage but, unlike a neon test light or voltage probe, it quantifies the reading. This is especially useful when you suspect low volt age. To test for voltage, first select the AC voltage function on the VOM, and then pick a range just above the receptacle’s voltage (choose the highest range when testing unknown voltage). Holding VOM test leads by their insulating sleeves, carefully insert probes into receptacle. Reading should be within 10 percent of the receptacle’s rated voltage (either 120 volts or 240 volts).
Testing for DC voltage---To measure battery voltage, select DC voltage function and appropriate range on VOM. Touch red probe to positive (+) side of circuit and black probe to negative (-) side. Reading should be within 20 percent of rating on appliance or battery. For a more accurate reading, try to check batteries under load, but only if it’s possible to run the appliance safely while you conduct the test.
Testing for resistance---A resistance test is a good way to check whether a heating element, for example, is bad. A resistance test can be done only when at least one of the leads to a component is disconnected. Set meter as for continuity test at left. Unplug appliance and disconnect element. Touch meter probes to both terminals and compare reading to appliance specifications. In general, if an analog meter’s needle sweeps toward zero or if a digital meter’s reading is low (below 120 ohms for a standard range element), element is OK. A reading of infinity indicates an open circuit.
Testing AC circuit loading --- To test a house circuit’s capacity, and to find out whether it can handle a new appliance, test a receptacle on that circuit for voltage as described at left. Once you’ve obtained a reading, remove VOM probes, plug appliance into receptacle, and turn appliance on. Holding VOM test leads by their insulating sleeves, carefully insert probes into free socket. If voltage drops 10 volts or more from first reading, circuit capacity is not sufficient for that appliance. Try the appliance on another circuit or consult an electrician.
!! FOR YOUR SAFETY!!
!! A volt-ohm meter is an invaluable diagnostic tool for attempting appliance or other electrical repairs. But if not used correctly, a VOM can be dangerous. Be sure you know what you want to test (ohms, volts, or cur rent) before touching tester probes to a volt age source. Any tests on the ohms (resistance) scale must be done on an unplugged appliance or dead circuit. If the meter is set on the ohms scale and the probes come into contact with voltage, the meter can sustain internal damage.
Voltage tests involve even greater risk since you’re probing potentially deadly voltage. Always hold VOM test leads by their insulating sleeves and exercise great care when touching the metal probes to a live receptacle or other voltage source. Never touch the metal probes when they’re in contact with a voltage source.
Although there is no alternative to a volt-ohm meter if you need to determine actual voltages, a voltage probe is a much safer alternative when all you need to know is whether or not a particular circuit is live.
The first step in appliance repair is simple: check the warranty. Most manufacturers provide free service on their products for a year or more—a benefit you may forfeit if you undertake a repair yourself. If a broken appliance is still under warranty, let the manufacturer repair it. Some companies also offer extended service contracts. Although a service contract can be expensive, it’s an option to consider if the appliance is used heavily and you would rather not tackle major repairs.
If you have neither a warranty nor a service contract, try fixing the appliance yourself. Many repairs are simple enough that a layperson with a little patience can do them. Most appliance problems are caused by a single component or connection. In addition, the guts of many appliances are very similar. Once you’ve fixed your vacuum cleaner motor, for example, you’ll have the know-bow necessary to repair a blender or mixer motor.
What to repair. Large appliances such as washers and dryers can sometimes be the simplest to fix; they are designed to be taken apart, and the most serviceable components are usually accessible. Inexpensive small appliances, however, are sometimes designed to be discarded rather than repaired. Manufacturers may discourage repairs on such appliances by sealing the housing or by assembling it with fasteners that require special tools for removal.
Not all appliances with serviceable parts can or should be repaired by their owners. Some manufacturers place a label on the appliance warning that repairs should be undertaken only by an authorized service center. Even though you may be able to open the appliance, you might not be able to buy the parts to repair it.
Many new appliances come with some type of electronic control, such as a digital timing clock. These components are durable but are not readily serviceable if they go bad; generally the entire component must be replaced.
Avoid needless repairs. Don’t take the appliance apart unless you have to. Start by looking for the obvious: Is the machine unplugged? Is the circuit breaker off or the fuse blown? Are you using the appliance improperly? Problems such as these generate more than a third of all service calls. Then check the owner’s manual for maintenance and troubleshooting tips. A little effort—putting a few drops of oil on a fan bearing or cleaning the filter on a vacuum cleaner—might be all it takes to get an uncooperative appliance running like new again.
An appliance ratings plate lists, at the very least, the device’s model (or catalog) number and a serial number—information you’ll probably need to order parts. The plate may also rate the appliance for watts, volts, amps, or RPM—information that can help you decide whether the appliance is overloading the circuit it’s plugged into. The plate shown here also gives the pump’s capacity: 3,600 GPH (gallons per hour).
The next step is to check the power cord and plug for fraying and breaks (see General troubleshooting). If you must disassemble the appliance, remove as few parts as possible. If you do remove a part, mark connecting wires with tape or sketch their alignment. Don’t tamper with calibrated devices such as thermostats, particularly if their adjusting screws are secured with a drop of plastic as a reminder to leave them alone.
Getting parts. Parts lists are sometimes included in the service manual (a good reason to keep the manual). Check the list for the name and number of the part you’re looking for, and check the appliance rating plate (see below, left) for the make, model number, and serial number. With this information you can order the part from the manufacturer or from one of its authorized service centers (Google the part number).
Reading wiring diagrams
Simple wiring diagram:
A wiring diagram is a guide to the inner workings of an appliance. On a typical diagram, straight lines represent conductors and a variety of symbols represent individual electrical components such as switches, fuses, and motors. Some of the more common wiring diagram symbols are shown below, but there are many others.
The diagram for any appliance may seem daunting at first glance, but reading it isn't difficult. To get your bearings, start at the point where electricity enters the appliance; then trace the flow as it passes through various components and back to the power supply. In the diagram above, for example, light B is energized whenever the appliance is plugged in; light A and the heating element are controlled by the switch. If you already know where the problem may be, focus on the components leading to and from it.
The owner's manual may contain a wiring diagram; if not, try ordering one from the manufacturer. On some large appliances, the diagram is on the back of a cabinet panel.
Motor symbols: Single-speed, Two-speed, Timer or clock
Switch symbols: Normally closed, Normally open, Multi-position
Load symbols: Ballast, Neon lamp (AC), Incandescent lamp, Fluorescent lamp, Resistor or heater
Before working on an appliance, make it’s unplugged. Check its manual to identify potential hazards. Certain microwave components, for example, should be fixed only by professionals. The sealed parts of appliances that are used or washed in water should also be left to professionals; such parts are nearly impossible to reseal properly.
Your next step is to find the fasteners that hold the case of the appliance together. As the drawings below indicate, they may be hard to locate.
Because reassembly is generally the reverse of disassembly, pay close attention to the exact sequence in which you remove parts. It’s a good idea to make a sketch of the assembled parts or to take a Polaroid picture of them. Making a light scribe mark across the junction of mating components is also helpful. Another trick is to arrange small parts on a strip of masking tape as you remove them. At the very least, group small parts and fasteners together in saucers. Note how parts are oriented— which end of a control shaft is up, or which side of a bearing faces forward.
A dot of paint will help you keep track of orientation. Pay particular attention to the location and position of washers. Most appliances are carefully engineered—every marking, part, tab, and notch has its purpose. A notch, for example, may be used to keep a motor bearing from rotating. The following techniques will make appliance disassembly much easier:
• To loosen a metal part that’s force-fitted into plastic, try warming the plastic with a hair dryer.
• To remove a tight-fitting control knob, slip a rag behind it, then pull evenly on the rag.
• Remember that nuts and bolts on rotating parts may have left-hand threads. Forcing them out the wrong way can strip the threads.
• When replacing an electrical part, remove the leads from the old part and attach them to the new part one by one.
• Don’t remove dials or control cams unless absolutely necessary; they can be difficult to replace.
• Wrap the jaws of pliers with tape to protect finishes.
• To loosen rusted screws, use penetrating oil and patience, not force.
• Work on a clean uncluttered surface; keep parts out of a child’s reach.
Special-purpose fasteners. Many new appliances are assembled with metric fasteners and Torx or square-drive screws. Metric wrenches and Torx and other special drivers are sold at many hardware stores and home centers. To discourage owner servicing, manufacturers sometimes seal appliances with unusual fasteners that may be difficult or impossible to remove.
Hidden fasteners and trick connections:
To loosen hidden spring clips, such as those securing a dryer top, slip a stiff tape-wrapped putty knife under appliance top and push knife against clip.
Press decorative facings with finger to find hidden screws. Use knife to lift facing after softening glue with hair dryer. Use contact cement to re-glue facing.
A dial cap (or the dial itself) may hide a fastener. Use a knife to gently pry off a cap. Remove a dial only if necessary; mark its position with tape first.
Remove plastic screw caps with a screwdriver or other strong, sharp instrument. Minor surface marring is probably inevitable.
The flexibility of plastic allows plastic parts to be connected by tab-and-notch arrangements that are easy to pry apart if you work slowly and carefully.
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!! FOR YOUR SAFETY !!
Before testing or repairing an appliance, unplug it. If you can’t unplug it, turn off the power at the main service panel.
Don’t use metal instruments to probe the interior of appliances, especially open-coil heating appliances such as toasters. You could short-circuit the appliance and receive a shock.
Never move an appliance connected to a gas or water line without first disconnecting it.
If you receive a shock when touching any appliance, disconnect the power immediately.
Never light a match near a malfunctioning combustion appliance, such as a gas dryer, stove, or furnace. If you smell gas, don’t turn on the lights—a small spark in an outlet box could trigger an explosion. Instead, shut off the gas, open the windows, and call the gas company from a neighbor’s house.
Get help when moving heavy appliances.
Never circumvent built-in safety devices.
Remember to discharge capacitors before starting a repair job.
Buy only electrical components listed by Underwriters Laboratories.
Beware of sharp metal edges when removing service panels or reaching inside an appliance. Don’t run an appliance with the access panel removed unless absolutely necessary. Avoid moving parts; don’t touch electrical terminals.
After servicing an appliance, check it for ground faults before plugging it in.
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Wires, cords, and plugs
Wires and cords:
Electrical wires are usually made of solid or stranded copper, sheathed in rubber, plastic, or heat-resistant insulation. Wire sizes are designated by American Wire Gauge (AWG) numbers: the higher the number, the smaller the wire and the lower its amperage rating. The wiring within small appliances is typically small-gauge stranded wire insulated in a variety of colors. Most wires found in household lighting and small-appliance circuits (AWG Nos. 10, 12, and 14) are solid. The cable used in household wiring consists of two or more insulated wires enclosed in a thermoplastic covering. Power cords are two or more insulated wires joined to bring power to a lamp or appliance. On flat lamp and small-appliance cords, the neutral conductor can usually be identified by a molded ridge on its insulation.
A replacement wire or cord, available at electrical parts suppliers or hardware stores, must be of the same gauge and type as the original. (Gauge, type, and other information are marked on the insulation.) A power cord’s amperage rating should match that of the appliance it’s connected to. All heating appliance wiring must have heat-resistant insulation. If you’re unsure of the type of wire required, show a sample of the wire you are replacing to the supplier.
Small-gauge appliance wire connects internal components of small appliances.
Zip cord is a two-wire 12- or 14-gauge cord used mostly on lamps.
Two-wire 14- or 16-gauge cord is used on small appliances with two-prong plugs.
Heater cord has heat-resistant insulation for appliances such as irons, toasters, and portable space heaters.
Three-wire 12- or 14-gauge cord is used on 120-volt appliances that have grounded three-prong plugs.
Three-wire 6- or 8-gauge cord delivers power to ranges, large air conditioners, and other heavy-duty 240-volt appliances.
How to strip wire--- Most appliance repairs call for stripping insulation from a wire. When doing so, be careful not to cut into the wire. Nicked wires are weaker, carry less current, and are more likely to overheat or break. If you use a knife to strip wire, take care not to cut yourself; a multi purpose tool or wire stripper is safer.
1. With wire pressed against a board, use a jackknife to shave off a strip of insulation on one side of wire.
2. Peel back remaining insulation. With stranded wire, make sure no strands remain with insulation.
3. Slice off loose insulation. Cut cleanly so no loose strands of insulation remain.
4. Twist stranded wires clock-wise. For better connections, tin ends of stranded wire with solder.
To strip wire with a multi purpose tool, feed wire into hole of correct gauge. Close and rotate tool to cut insulation.
Squeeze handle and push tool away from you to remove cut insulation. Tool leaves tapered cut on remaining insulation.
Making connections: Wire to terminal
Whether you’re connecting wire to a wall switch, a receptacle, or a terminal inside an appliance, make sure all connections are tight and neat, with no frayed ends or loose strands. It’s good practice to tin the ends of stranded wires before attaching them to a screw terminal or inserting them in a push-in terminal. Most wiring connections inside a power tool or appliance are soldered or involve terminals that are crimped onto wire ends. The most common terminal is the spade lug that slides onto a plate terminal. Round or U-shaped crimp-on terminals attach to screw terminals. The color of the insulation on crimp- on terminals indicates the size wire they fit.
Wire ends should fit completely beneath screw terminal. Always loop wire clockwise around screw terminal.
To install spade lug, cut ½ in. of insulation from wire, insert wire into lug sleeve, and crimp with a multipurpose tool.
To disengage spade lug, push lug off plate terminal with a screwdriver. If you pull on the wire itself, you may damage it.
To connect wire to screw terminal, strip in. of insulation from wire end; bend wire into a loop with long-nose pliers. Hook wire clockwise around screw shaft. Tighten screw.
To wire push-in terminal, feed solid or tinned stranded wire into holes (gauge shows how much insulation to strip). To release wire, turn off power; push screwdriver tip into slot.
Making connections: Wire to wire
The easiest way to join wires is with a screw-on wire connector or, fora more secure connection, a crimp-on wire cap (the latter is particularly useful for joining wires in appliances that vibrate). Be sure to use the right size connector for the type and number of wires you’re joining (the package usually includes a sizing chart). Strip off only enough insulation so that no bare wire is exposed once the connector is in place. To make sure that wires joined with a wire connector don’t come loose, wrap the splice with electrical tape. Wires can also be soldered together. For a discussion of soldering, see below.
Pigtails. Never connect more than a single wire directly to a single terminal. To join two hot wires to a switch terminal, for example, first turn off power to the circuit. Use a wire connector to join the two wires to a short length of wire called a pigtail; then connect the pigtail to the switch terminal.
Solid wires. Hold stripped wires together and twist the connector on clockwise. Don’t overtighten or you could break the wire.
Stranded wires. First twist each stripped wire clockwise; then twist them together and twist on the wire connector.
Solid to stranded wire. Twist stranded wire clockwise. Holding solid and stranded wires together, screw on connector.
To join wires with crimp-on cap, twist bare wire ends together, cap the wires, and crimp with multipurpose tool.
Faulty plugs are a leading cause of appliance failure. Replace any plug that is cracked, burnt, or has loose prongs. A round-cord plug whose insulating disc is broken or missing must also be replaced. In general, replace a plug with one of the same type. The most common type is the flat-cord plug, which connects to zip cord by means of terminal screws. You can replace a flat-cord plug with a quick-connect plug, but only if it won’t be subject to repeated insertion and removal. Some lamps and many appliances use round cords and round-cord plugs.
A polarized plug, in which one prong is wider than the other, fits into a polarized receptacle only one way. A safety feature designed to keep hot and neutral sides consistent throughout a circuit, polarity works only if the receptacle and plug are properly wired. When installing a polarized plug, connect the cord’s neutral (ridged) wire to the wider prong.
Flat-cord plugs are found on lamps and light-duty appliances.
Quick-connect plugs are easy to attach but lack durability.
Molded plugs form a single sealed unit with their cord.
Round-cord plugs come in standard and heavy-duty versions. The latter may feature a prong configuration specific to a particular large appliance.
Twist-lock plugs cannot be removed inadvertently; they require matching receptacle.
Heater plugs connect detachable cords to fryers and other heating appliances.
How to replace plugs:
Flat-cord plug. Unplug appliance. Remove old plug by cutting cord with cutting pliers. Unscrew core of new plug from shell (or, depending on plug type, separate shell halves or remove insulating disc). Separate wires at cord’s end. Strip ¾ in. of insulation from each wire. Feed wires into shell (if there’s room in shell, tie Underwriters knot as shown below). Loop each wire over notch (if any) in terminal; then connect wire to terminal screw. Reassemble plug.
Quick-connect plug. Remove old plug as described above. Don’t separate or strip wire ends. Pinch prongs of new plug and pull out plug core.
Feed cord through rear of shell. Spread prongs apart and insert cord into plug core. Squeeze prongs together to pierce cord; slide core back into shell.
Round-cord plug. Cut off old plug. Pry off insulating disc from new plug or remove plug core from shell. Cut 1½ in. off cord jacket and ¾ in. off wire insulation. Feed cord into plug. Tie Underwriters knot as shown. Connect wires to plug terminals. In three-prong plug, tie Underwriters knot in black and white wires; hook white wire to silver screw, black to brass, and green to green. Reassemble plug: tighten clamp, if any.