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In appliances like waffle irons and toaster ovens, these are usually welded. This is necessary to withstand the high temperatures and it is cheap and reliable as well. Welding is not normally an option for the doit yourselfer. However, if you are somewhat suicidal, see the section: "Improvised welding repair of heating elements" for a more drastic approach. I have used nuts and bolts, say 6-32, bolt, wire, washer, wire, washer, lockwasher, nut. Depending on how close to the actual really hot element it is, this may work. If you are connecting to the coiled element, leave a straight section near the joint - it won't get as hot. The use of high temperature solder or brazing might also work. The best approach is probably to use high temperature crimp connectors: (The following from: sad@garcia.efn.org (Stephen Dunbar)) You can connect heating element wires with high-temperature solderless connectors that are crimped onto the wires. Be sure to get the special high-temp connectors; the ordinary kind will rapidly oxidize and fall apart at high temperatures. If you want to join two wires to each other, you'll need either a butt splice connector (joins the wires end-to-end) or a parallel splice connector (the wires go into the connector side-by-side). To fasten a wire to a screw terminal you can use a ring or spade connector (though as noted above, a screw, nut, and washer(s) should work fine --- sam). If your waffle iron has quick disconnect terminals you'll need the opposite gender disconnect (AKA Faston). These come in both .187" and .250" widths. Your best bet for getting these connectors in small quantity is probably a local appliance parts outlet that caters to do-it-yourselfers. If you can't find what you need there, try Newark Electronics (branches all over the place). I have an old copy of their catalog which lists SPC Technology Voltrex Brand High Temperature Barrel Terminals in several styles: ring, spade, disconnect, and butt splice. The prices were around $10 to $12 per 100 (this catalog is a couple of years old) for wires in the 22-18 or 16-14AWG size ranges, almost twice that for the heftier wire gauges. (Be sure to determine the wire gauge of your heating elements so you can get the right size terminal.) You can spend a *lot* of money on crimp tools, but for occasional light use you can probably get by with one of those $10 gadgets that crimp, strip & cut wires, and cut bolts--the sort of thing you'd find in your local home center or Radio Shack. (From: Nigel Cook (diverse@tcp.co.uk)). The thin stainless steel strip found spot welded to multicell NiCd batteries make good crimps for joining breaks in heater resistance wire. Form a small length of this strip around a needle or something similar to make a tight spiral with enough clearance to go over doubled-up heater wire. Abraid or file the cut ends of the broken wire. Crimp into place with a double lever action crimper. If there is an area of brittle heating element around the break then cut out and splice in a replacement section with two such crimps. Such a repair to my hot-air paint stripper (indispensable tool in my electronics tool-kit) has survived at least 50 hours. (From: Dan Sternberg (steberg@erols.com)). Another old trick for nichrome repair is to make a paste of Borax, twist the two broken end together, and energize the circuit. A form of bond welding takes place. I've have used this on electric clothes dryer heater elements with good luck.
Solenoids are actuators operated by electromagnets that are used to operate valves, slide or engage various parts, eject or prevent opening of a door, and other functions. While shapes and sizes may vary, all electrically operated solenoids use an electromagnet - AC or DC - to pull on a movable piece called an armature which generally moves back and forth but rotary motion is also possible. Solenoids are usually two position devices - they are not used to provide intermediate amounts of force or travel like motors. Sizes ranges from small 1/2" long units providing a fraction of an ounce of force and 1/8" travel to large 3" long units providing many pounds of force with travels of 2" or more. Testing: Inspect for free movement. Use an ohmmeter to confirm that the coil is intact. There could be other problems like shorted turns in the coil but these would be less common than lack of lubrication or an open coil. Check voltage on operating solenoid to determine whether drive power is present.
A variety of small electronic components may be found in appliances though unlike true electronic equipment, these do not usually run the show. Resistors - may be used in various ways to adjust the current flowing in part of a circuit. Many different types of resistors are possible - tiny carbon or metal film types looking like small cylindrical objects often with colored bands which indicate the value. Power resistors - larger cylindrical or rectangular often ceramic coated. These may get quite hot during operation. Their resistance value and power rating are usually printed on the resistor. Capacitors - a variety of shapes and sizes. Some may look like disks, jelly beans, cylinders, boxes, etc. Their value is often marked in uF or pF. Diodes or rectifiers - solid state devices that permit electric current to only flow in one direction (positive current in the direction of the arrow when marked this way). These are most often used in appliances to change AC to DC or to cut the power to a motor or heater (by allowing only half of the AC current to pass). For more information on these types of components, see any good introductory electronics text.
A large part of the functionality of modern appliances is based on the
use of motors of one form or another. We devote an entire chapter to
motors. The following is just an introduction.
Motors come in all shapes and sizes but most found in small appliances
can be classified into 5 groups:
1. Universal motors.
2. Single phase induction motors
3. Shaded pole induction motors.
4. Small permanent magnet DC motors.
5. DC brushless motors.
6. Synchronous timing motors.
See the chapter: "Motors 101" for more detailed information on the common
types of motors found in small appliances.
The entire purpose of a particular appliance may be to move air or this may simply be needed for cooling. Obviously, portable and window fans are an example of the former. However, many appliances have built in fans you may not even be aware of as part of the motor(s) or other rotating components. There are two primary types of configurations: 1. Bladed fans - we are all familiar with the common desk or window fan. This uses a set of rotating blades - typically 3-5 to gather and direct air. In the specific case of an oscillating desk fan, a gear drive linked to the motor also permits the general direction of air movement to be controlled in a back-and-forth motion. I recently saw one where in addition to moving back and forth, the front grille can be set to rotate at an adjustable rate providing more variation in air flow. The direction of the air movement with respect to blade rotation is determined by the pitch - the tilt - of the blades. Although reversing air direction is possible by reversing the motor, one direction is usually more effective than the other due to the curve of the blades. 2. Centrifugal blowers. These use a structure that looks similar to a squirrel cage to suck air from the center and direct it out a plenum formed around the blower. While these may be found in all sizes, the most common household application is in the vacuum cleaner. Large versions of these blowers are used in central heating and airconditioning systems, window airconditioners, and oil burners. Direction of rotation of the blower motor does not change the direction of airflow. However, one direction will be more effective than the other (where the blower is rotating in the same direction as the way exit port on the air plenum points. Because of this, it is not possible for a vacuum cleaner to blow out the suction hose due to a reversed motor (which in itself is for all intents and purposes, impossible as well). This is usually caused by back flow due to a blockage.
The shafts of rotating parts normally are mounted in such a way that friction is minimized - to the extent needed for the application. A bearing is any such joint with more specific terms used to describe the typical types found in small appliances - or lawnmower, automobile engines, or 100 MW turbines. Plain bearings - these consist of an outer sleeve called a bushing in which a polished shaft rotates. The bushing may be made of a metal like brass or bronze or a plastic material like Teflon(tm). The shaft is usually made of steel though other materials may be found depending on the particular needs. Where a metal bushing is used, there must be means provided for lubrication. This may take the form of oiling grooves or holes and an oil reservoir (usually a saturated wad of felt) or the bushing itself may be sintered. Metal particles are compressed at high temperature and pressure resulting in a very porous but strong material which retains the lubricating oil. Under normal conditions, a plain bearing wears only during start and stop cycles. While the shaft is rotating at any reasonable speed, there is no metal to metal contact and thus no wear. With a properly designed and maintained bearing of this type, a very thin oil film entirely supports the shaft - thus the importance of clean oil. Your automobile engine's crankshaft is entirely supported by these types of bearings. Eventually, even 'lubricated for life' bearings of this type may need to be disassembled, cleaned, and lubricated. The plain bearings in small appliances must be lubricated using a proper light oil like electric motor or machine oil - not automotive engine oil and NEVER NEVER WD40. NEVER, ever, use WD40 as a lubricant (unless specifically recommended by the manufacturer of the equipment, that is)! WD40 is not a good lubricant despite the claims on the label. Legend has it that the WD actually is an abbreviation for Water Displacer - which is one of the functions of WD40 when used to coat tools. WD40 is much too thin to do any good as a general lubricant and will quickly collect dirt and dry up. It is also quite flammable and a pretty good solvent - there is no telling what will be affected by this. WD40 has its uses but lubrication unless specifically recommended by the manufacturer (of the equipment, that is) is not one of them. Results initially may be good with that instant gratification that comes from something returning to life. However, the lighter fractions of WD40 evaporate in a few days For very small metal-in-plastic types, the following might be useful: (From: Frank MacLachlan (fpm@bach.n2.net)). "I've had good luck with a spray lubricant called SuperLube. It contains a solvent which evaporates and leaves a Teflon film which doesn't migrate or retain dust. I spray some into a spray paint cap and then apply the solution with a toothpick, allowing the lubricant to wick into the bearing areas. Worked great for some balky Logitech mice I purchased at a local swap meet." Frictionless bearings are usually of the ball or roller variety. An inner ring called a race rotates supported by a series of balls or rollers inside an outer race. There is virtually no friction even at stand-still with these bearings. However, rolling metal to metal contact is maintained at all speeds so they are not quite as wear free as a properly maintained and constantly rotating plain bearing. However, for all practical purposes in small appliances, these will last a long time and are rarely a problem. Sometimes, reworking an appliance to use a ball bearing instead of a plain bearing is a worthwhile effort - I have done this with electric drills and shop vacs. They run smoother and quieter with ball bearings. Not surprisingly, higher-end models of these devices (which use ball bearings) share parts with the cheaper versions and finding standard ball bearings that would fit was not difficult.
While these are not that common on small appliances, they may be present in washing machines, dryers, dishwashers. and refrigerator defrost timers. They in themselves may be considered small appliances - and often can be repaired or replaced easily. Most of these are just small timing motors (synchronous motors running off of the AC line) which rotate one or more cams (disks with bumps) which activated one or more switches at appropriate times during the rotation cycle. Typical cycle times range from a minute or less to several hours (refrigerator defrost timer). Most like washing machine timers are in the 1 hour range. Sometimes, the motor is stopped during certain portions of the cycle awaiting completion of some other operation (i.e., fill). These controllers therefore consist of several parts: * Timing motor. A very small synchronous AC line operated motor with an integral gear train is most common. Sometimes, the rotor and geartrain are in a sealed, easily replaceable unit - a little metal case that clamps within the pole pieces of the AC field magnet. In other cases, it is a separate motor assembly or an integral part of the overall timer mechanism. * Escapement (not present on all types). This is a device which converts the continuous rotation of the timing motor to a rapid movement for each incremental cam position. A common type is a movement every 45 seconds to the next position. This assures that the make or break action of the switches is rapid minimizing arcing. * Cam(s). One or more cams made of fiber composite, plastic, or metal, are rotated on a common shaft. There will be one set of switch contacts for each circuit that needs to be controlled. * Switches. These will either be exposed sets of contacts or enclosed 'microswitches' which are operated by the cams. Testing: If the controller is not working at all, check for power to the motor. Listen for the sound of the motor parts rotating. Check for gummed up lubrication or broken parts. If some of the circuits do not work, check the switches for dirty or worn contacts or broken parts.
These can range from a simple R-C (resistance-capacitance) circuit to provide the time delay in a toaster to sophisticated microprocessor based systems for programming of a coffee maker or microwave oven. While generally quite reliable, bad solder connections are always a possibility as well as failed parts due to operation in an environment prone to temperature extremes. Testing: Check for bad solder connections and connectors that need to be cleaned and reseated. Inspect for obviously broken or burned parts. Test components for proper value. For digital clock/programmers or microprocessor based controllers, not much else can be done without a schematic - which not likely to be easily available.
More and more small appliances and power tools are cutting their cords and going to battery power. Although there are a large number of battery types, the most common for power applications (as opposed to hearing aids, for example) are: * Alkaline - primary (non-rechargeable, for the most part), long shelf life, high energy density. * Lithium - primary and secondary (rechargeable) available though most appliance applications (which are just beginning to develop) are not rechargeable. Long shelf life, very high energy density. Still quite expensive. * Nickel Cadmium - most common rechargeable technology in cordless appliances and power tools. However, relatively fast self discharge and on about half the capacity of a similar sized Alkaline. * Lead-Acid - secondary type similar to the battery in your automobile but packaged in a totally sealed container which is virtually indestructible and leakproof. Medium self discharge rate but will deteriorate if left discharged for an extended period of time. See the chapter: "Batteries" for more information.
These wall adapters are used to power many small electronic devices and appliances directly and/or to recharge their batteries. They usually plug directly into the wall socket and convert the 115 VAC (U.S.) to a lower voltage - 3 V to 24 V AC or DC typical. More sophisticated units may actually be a switching power supply with smart electronic control of battery charging and power management. The following are typical types: * AC output - 3 to 24 VAC (or more) at 50 mA to 3 A. The only internal component is a power transformer which may include a thermal or ordinary fuse for protection. * DC output - 3 to 24 VDC (or more, under load) at 50 mA to 1.5 A. In addition to the power transformer, there is a rectifier, filter capacitor, and possibly a three terminal IC regulator (not that common). Some type of protection will probably be built in as well. * Universal/switching power supply - typically 6 to 18 VDC at .5 to 3 A. These will usually operate off of any voltage input from 90 to 240 VAC (or DC) and provide a well regulator output. There will generally be an internal fuse as well as overvoltage and overcurrent protection. In some cases, a single adapter will put out multiple voltages. See the chapter: "AC Adapters and Transformers" for more information.
This is the most popular type of lighting for reading or general illumination. The type described in this section takes normal 115 VAC light bulbs. The common table lamp is just a light duty cordset, switch, and sockets for one or more incandescent light bulbs. In many cases, the switch and socket are combined into one assembly. In other designs, particularly where more than one bulb can be lit independently (for example, a large bulb up top and a night light in the base), a separate switch (rotary or push-push) selects the light bulb(s) to be turned on. For the most common combined switch and socket, there are several varieties and these are all generally interchangeable. Therefore, if you want to take advantage of the added convenience of a 3-way bulb allowing low, medium, and high illumination, it is a simple matter to replace the simple on-off switch in your lamp with a 3-way switch (not to be confused with the 3-way switches used in house wiring to control a single light fixture from 2 places). Push-push, pull chain, and rotary switches are common for simple on-off control. The 3-way switches are usually of the rotary variety with off-low-medium-high selected as the knob is rotated. The 3-way bulb has two filaments which can be switched on individually or in combination to provide the 3 levels of illumination. Dimmer sockets can often be substituted for the normal kind as long as conventional incandescent bulbs (and not compact fluorescents) are to be used. Touch and even sound activated switch-sockets are also available though my personal recommendation is to stay away from them. Most common problems: burned out bulb, worn switch, bad plug or cord. Where the light flickers, particularly if jiggling or tapping on the switch has an effect, a bad switch is almost always the problem. Switch failure is more common when using high wattage bulbs but can occur just due to normal wear and tear. Replacements for most common switches and sockets are readily available at large hardware stores, home centers, and electrical supply houses. It is best to take along the old switch so that an exact match (if desired) can be obtained. While the thread sizes for the screw on socket shells are quite standard, some older lamps may have an unusual size. For more complicated switches with multiple sockets, label or otherwise record the wiring. If color coded, cut the wires so that the colors are retained at both the lamp and switch ends.
As noted in the Introduction, virtually any table lamp can be restored to like-new electrical condition for a few dollars at most. The following is the detailed procedure for the majority of common table lamps found in the U.S. This is assumed to be the type of lamp which has a combination socket and switch with a metal (brass-colored usually) outer shell. It is your decision as to whether a simple on-off switch or a 3-way type is to be used - they are usually interchangeable and a normal light bulb can be put into a 3-way socket (two clicks of the knob will be needed to switch a normal light bulb on or off, however). You can also put a 3-way bulb into a normal socket but you will, of course, only get one level of illumination (medium). For lamps with lighted bases, also see the section: "Lamps with night-light bulbs in their base". You will need: (1) a new socket/switch of the appropriate type and (2) a new cordset (if you want to replace this as well). A polarized type plug is desirable to minimize the possibility of shock when changing bulbs. A medium size straight blade screwdriver and wire strippers are the only required tools. First, remove and set aside any shade, frosted chimney, and other cosmetic attachments. Unplug the lamp!!! Examining the metal shell, you will note that it is in two pieces. If you look carefully, there will probably be indications of where firmly pressing the top portion will allow it to be separated from the bottom part mounted on the lamp. These are usually near where the knob, button, or chain, enters the switch. Sometimes, a fine screwdriver blade will be useful to gently pry the two halves apart. With the top part removed, unscrew and disconnect two wires and remove the switch. If desired, loosen the set screw (if any) and unscrew the bottom portion of the shell. If you are simply replacing the switch, at this point you would just attach the new one and reassemble in reverse order. Screw on the bottom of the new switch enough so that it is either tight or until the threads are fully engaged but not pressing on or protruding above the cardboard insulating disk in the bottom half of the shell. If the entire assembly is still loose, it should be possible to tighten hardware on the bottom of the lamp to secure it against rotation. Note: it is important to do this to avoid eventual damage to the wires should the switch move around significantly during normal use. To replace the cordset, you may need to partially remove any felt pad that may be glued to the base of the lamp. Sometimes, it is possible to cut off the old plug, attach the new cord to the end of these wires, and pull it through. However, in most cases, there will be a knot or other strain relief in the original cord which will make this impossible (and you will want to replicate this in the replacement as well). Therefore, if needed, carefully peel back the felt pad only enough to gain access to the interior. In some cases, just cutting a small X in the center will allow sufficient access and this can be easily patched with a piece of cloth tape. Install the new cord in exactly the same way as the original with a knot for a strain relief if needed. If there was no strain relief to begin with, adding a knot is a good idea if there is space for one in the base. Snake the cord through to the top of the lamp. Strip the ends of the wires to a length of about 1/2 inch and twist the strands tightly together in a clockwise direction. If you are using a cordset with a polarized plug, identify the wire attached to the wide prong (with a continuity checker or ohmmeter if it is not clearly marked by a stripe on the insulation) and connect it to the silver colored screw. Connect the wire attached to the narrow prong to the brass colored screw. Always wrap in a clockwise direction. See the section: "Attaching wires to screw terminals". Confirm that there are no loose wire strands and that the insulation is nearly flush with the screw to avoid possible shorts. Pop the shell top with its insulating cardboard sleeve over the switch and press firmly onto the base. There should be a very distinct click as it locks in place. If needed, adjust the strain relief at the base of the lamp so that pulling on the cord does not apply any tension to the wires attached to the switch. Tighten the nut in the base of the lamp holding the entire assembly in place if the socket is still loose and rotates easily. Don't overdo it - the supporting structure is often just a glass jar or something similar. Put a drop of Loctite, nail polish, Duco cement, or something similar - or a second nut - on the threads to prevent the nut from loosening. Use some household cement to reattach the felt pad you peeled back earlier.
These are the types of lamps where either the normal bulb on top or a smaller one in the base (or both) can be turned on using a turn-key or pull-chain. This is a standard, if somewhat unusual socket. It is basically the same as a 3-way type but with the extra connection going to the bulb in the base of the lamp. In the old days when sockets were assembled with screws instead of rivets, it might have been possible to modify a new 3-way socket to provide the extra connection. An electrical supply parts distributor or lamp store should have what you need or be able to order it for you. Take note of the connections as you remove the old socket to avoid mistakes. When routing the wires to the bulb in the base, avoid allowing the hot bulb from contacting the insulation - the plastic stuff might melt (for a 7 W or less wattage bulb and high temperature insulation is probably not an issue, however).
These include several types but they all use a transformer to reduce the 115 VAC to something lower like 12-24 V. Tensor(tm) (and their clones) high intensity lamps have been around for over 30 years and are essentially unchanged today. They use a low voltage transformer producing 12-24 VAC along with a special high output light bulb that looks similar to an automotive tail light. However, it uses substantially more current for the same voltage and puts out a much more intense, whiter light. These are not halogen lamps though their spectral characteristics are similar since the filaments run hotter than normal incandescents - and have shorter lives. Some will have multiple levels of illumination based on selecting taps on the transformer. Normal dimmers may not work (and should not be used) with these due to their transformer design - damage to the dimmer or lamp may result and this may be a fire hazard. Problems with Tensor lamps tend to center around the socket and switch. These may fail due to overheating as a result of the high temperature and high current operation. Replacements are available but they may take some effort to locate. A replacement lamp may be cheaper. (I often find complete Tensor lamps in perfect operating condition at garage sales for around $2.
Halogen lamps share many of the design characteristics of high intensity lamps in that they are designed for local high intensity lighting and use a transformer usually (though some may use solid state voltage conversion instead). While some halogen lamps come with dimmers, some of the advantages of the halogen cycle are lost if the bulbs are not run at full power. The worst case is where they are operated just below full power - too cool for the halogen cycle to take place but hot enough for substantial filament evaporation to occur. Should the dimmer portion of such a fixture fail or become unreliable, it may a blessing in disguise since the lamp will either run at full intensity or can be easily rewired to do so by bypassing the electronics and just using the on/off switch! WARNING: halogen bulbs run extremely hot and are a serious fire hazard and burn hazard if not properly enclosed. When changing a halogen bulb, wait ample time for the old one to cool or use an insulated non-flammable glove or pad to remove it. When installing the new bulb, make sure power is off, and do not touch it with your fingers - use a clean cloth or fresh paper towel. If you do accidentally touch it, clean with alcohol. Otherwise, finger oils may etch the quartz and result in early - possibly explosive failure - due to weakening of the quartz envelope.
These guidelines were prompted by a number of fires including some fatalities that have been linked to improper use of halogen lamps - in particular the high power torchiere variety of floor lamps. However, the guidelines apply to many other types of halogen lamps including work-lights, desk lamps, slide and overhead projectors, and other lamps or fixtures where the bulb is not entirely enclosed and thermally insulated from the exterior. (Source: The Associate Press except as noted). Safety groups recommend the following precautions for owners of halogen torchere lamps with tubular bulbs: * Place the lamps where they cannot be tipped over by children, pets, or strong drafts (away from open windows, for example). * Never use halogen lamps in children's bedrooms or playrooms where combustible objects like stuffed toys may be accidentally placed on top of or next to them. * Never use a replacement bulb of a higher wattage or of a different type than specified by the manufacturer. Avoid bulbs larger than 300 W. * Never attempt to replace or discard a bulb that is too hot to touch. Do not touch the new bulb with your fingers as the oils and acids may make them more prone to exploding. Clean the bulb thoroughly with isopropyl alcohol after any accidental contact (--- sam). * Never drape cloth over the lamp. * Operate the lamps at less than maximum wattage on a dimmer whenever possible. Note that this may not result in maximum life but will be safer due to the lower temperature of the bulb (--- sam). * Keep lamps away from elevated beds like bunk beds where the bedding may get too close to the bulb. * Never use unprotected halogen lamps in locations like bathrooms where water may splash resulting in the bulb exploding (--- sam). * Never operate lamps with their thermal or UV shields removed (--- sam).
Many things can cause the light bulb in a table lamp to flicker: * Loose bulb(s) :-). * Bad switch. These do wear out particularly if multiple high wattage bulbs are being used. If gently jiggling the switch results in flickering this is the most likely cause. * Bad connections. These could be anywhere but the most likely locations (where only a single lamp is involved) would be either at the screw terminals on the switch or from a plug that isn't making secure contact in the outlet - check it. * Voltage fluctuations. Occasional flickering when high wattage appliances kick in is not unusual especially if they are on the same branch circuit but could also be a symptom of other electrical problems like a loose Neutral connection - see the section: "Bad Neutral connections and flickering lights or worse". If a dimmer control is present, keep in mind that these are somewhat more sensitive to slight voltage fluctuations especially when set at low levels. You may simply not have noticed any flickering with a normal on/off switch.Go to [Next] segment
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