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Refer to the diagram in the section: "Electromechanical doorbells and chimes", Another button can be added in parallel with any of the existing ones (i.e., between points X and F or X and B in the diagram). The only restriction is that you may not be able to have more than one lighted button in each group as the current passing through the lighted bulbs may be enough to sound the chimes - at least weakly. If you cannot trace the wiring (it is buried inside the wall or ceiling) the only unknown is which side of the transformer to use. If you pick the wrong one, nothing will happen when you press the button.
The transmitter and receiver portion of these units are virtually identical to those of garage door operators. See the relevant sections on those units for problems with activation. The bell or chimes portion may be either an electromechanical type - a coil forming an electromagnet which pulls in a plunger to strike a gong or bell. See the section: "Electromechanical doorbells and chimes". Others are fully electronic synthesizing an appropriate tone, series of tones, or even a complete tune on demand. Repair of the electronics is beyond the scope of this document. However, there are several simple things that can be done: * Check for dead batteries and dirty battery contacts in both the pushbutton and chimes unit. * Confirm that the channel selection settings have not accidentally been changed on the pushbutton or chimes unit. Flick each switch back and forth (where switches are used) just to make sure they are firmly seated. * Check for improper programming or program loss due to a power failure (if AC operated) on units that are more sophisticated than a personal computer.
* For mechanical chimes, this is almost certainly an intermittent short
circuit in the button wiring or a defective button. First check or replace
the outside pushbutton switches as this is the most likely location due to
environment and small multilegged creatures.
* For electronics chimes, the problem could either be in the transmitter(s) or
chimes unit or due to external interference. Someone in your vicinity could
have the model also set to the default code (which is probably what you
have, correct?).
First, remove the batteries or kill power to all transmitters and wait see if
the problem still occurs.
- If it does, either the chimes unit is defective or there is an external
source of interference.
- If it now behaves, try each one individually to identify the culprit.
In some cases, a low battery could produce these symptoms as well.
Don't toss the electronic remains of that old garage door operator. It would probably be possible to use it as the basis for a wireless doorbell. Instead of starting the motor, use its output to enable an electronic chime or buzzer. The RF transmitter and receiver for a wireless chime is virtually identical to that of a typical garage door operator.
These consist of a base unit with some sort of direction display and knob and a motor unit to which the TV antenna is mounted. Of course, the troubleshooting of these installations is complicated, of course, by the remote and somewhat inaccessible location of the motor unit :-(. Before climbing up on the third story roof, confirm that you haven't lost power to the motor unit and/or base station and that the connections between them are secure. A common type of motor that may be used in these is a small AC split phase or capacitor run induction motor. The relative phase of the main and phase coils determines the direction. These probably run on 115 VAC. A capacitor may also be required in series with one of the windings. If the antenna does not turn, a bad capacitor or open winding on the motor is possible. See the chapter: "Motors 101" for more info on repair of these types of motors. The base unit is linked to the motor unit in such a way that the motor windings are powered with the appropriate phase relationship to turn the antenna based on the position of the direction control knob. This may be mechanical - just a set of switch contacts - or electronic - IR detectors, simple optical encoder, etc.
A variety of motor types are used depending on the type of tool. AC powered portable tools usually use a universal motor due to it high power/weight ratio and ease of electronic speed control. Cordless tools usually use a high performance permanent magnet DC motor. Stationary power tools almost always use some form of AC induction motor except where variable speed is required. See the sections on these types of motors for more details than the following summaries provide.
Line operated portable (corded) power tools usually use a universal type AC motor providing 3,000 to 30,000 RPM at the motor shaft. For the same power rating, these will be significantly lighter than an induction motor. A single or multiple stage gear reducer drops the relatively high speed at which these motors are most efficient to whatever the tool actually requires, increasing the torque as well. Universal motors can also be speed controlled relatively easily using a variant of a simple light dimmer type circuit. Excellent torque is maintained over a very wide range extending to nearly 0 RPM.
These are usually high performance permanent magnet DC motors using advanced high strength and exotic magnetic materials. They are very compact and light weight for their power output. As with all DC (brush type) motors, brush wear is a common problem. Speed control is easily accomplished by low cost electronic circuits which chop the power (pulse width modulation) rather than simply using a rheostat. This is much more efficient - extremely important with any battery operated device.
Stationary power tools which do not require continuous speed control will generally use some type of AC induction motor - split phase or capacitor start/run. The motors generally operate at a fixed speed of around either 1725 or 3450 RPM (U.S., 60 Hz power). Stepped pulleys or continuous mechanical speed/torque changers are used to obtain (usually) lower work piece speeds. For example, a typical drill press may have one or two sets of stepped pulleys providing 3 to 15 or more speeds by changing belt positions. A continuously variable cone drive is also available as an option on some models. This is extremely convenient but does add cost and is usually not found on less expensive models. An internal thermal overload protector may be incorporated into larger motors. WARNING: this may be self resetting. If the tool stops on its own, switch off and unplug it before attempting to determine the cause. Generally, these induction motors are virtually maintenance-free though cleaning, tensioning, and lubrication may be required of the drive system. However, electronic speed control of induction motors, while possible, is relatively complex and expensive requiring a variable frequency variable voltage power supply. Therefore, universal motors may be used on stationary tools like scroll saws with continuously variable electronic speed control.
One horsepower is equal to 746 watts of electrical power (100% efficiency). Therefore, the most you can get continuously from a normal 115 V 15 A outlet is about 2 HP. Any claims (for air compressors, for example) of higher ratings on a normal outlet are totally bogus. Companies such as Sears (Craftsman) like to specify 'Reserve Power' for their power tools which as best as I can determine refers to the power available for a short time and may relate to the mass - and inertia - of the rotating parts but not the continuous power available. This may be useful to help saw through a tough knot in a piece of hardwood but may not be terribly meaningful for a wet/dry vacuum! Therefore, pay most attention to the continuous power ratings if they can be found anywhere. A good indication is probably the maximum amps required for the electrical service. As with over-the-counter drugs, extra strength does not necessarily translate into faster relief, higher current does not always mean better performance, and horsepower ratings much above what you would compute from V x A may be more of a marketing gimmick than anything really beneficial.
Really old power tools had two wire cord plugs and no safety ground yet were of all metal (solid and heavy!) construction. I would recommend that as a matter of policy, these be retrofitted with a 3 wire grounded cordset. Newer ones have the grounded cordset while the newest 'double insulated tools' are of mostly plastic construction and are back to a 2 wire ungrounded cord. As with any electrical appliances, inspect cords regularly and repair or replace any that are seriously damaged - if the inner wiring is showing, nicked, or cut; if the plug is broken or gets hot during use, or where the cord is pulled from or broken at the strain relief.
The portable electric drill (now the rage is cordless) is probably one of the two first tools that any handyman should own (the other being a saber saw). It is used for many things in addition to drilling little holes - drilling large holes, sanding, polishing, driving screws, etc. Therefore, these tools get a lot of use - and abuse.
An AC line powered electric drill is just a universal motor with a two stage (typical) gear reduced powering a chuck to hold the drill bit or attachment. A continuous range speed control with a reversing switch is now standard on most AC line powered drills. Typical problems include: * Worn bearings. These may be replaceable. Also see the section: "Upgrading the bearings on a Craftsman drill". * Worn motor brushes. Replacements should be available. from the manufacturer or a motor/appliance repair shop. * Broken or chipped gears. This is rare under normal conditions but if the drill was abused, then failure is possible. * Bad cord or plug. Repair or replace for safety reasons. * Bad speed controller/reversing switch. Replacement trigger assemblies are available but may cost half as much as an entire new drill. One common wear item is the linear potentiometer operated by the trigger and this is not likely to be a standard component. The drill may work fine as a single speed model if this control fails. You could always use an inexpensive external motor speed controller in this case. * Bad motor. Failures are possible but unless abused, not nearly as common as other simple problems like bad brushes or bearings. It may not be cost effective to replace a bad armature or stator unless this is an expensive high quality drill or you have a similar model available for parts. * Rusted or gummed up chuck. (Or, lost chuck key!). The chuck is replaceable. Depending on type, it may mount with a right or left hand screw thread and possibly a right or left hand retaining screw through the center. See the owner's manual to determine what your drill uses as you could be attempting to tighten rather than loosen the chuck if you turn the wrong way. If by some slight chance you do not have the owner's manual :-), a reversible drill will usually have a left hand (reversed) thread on the chuck and a retaining screw with a right hand (normal) thread. A non-reversible drill will only have a right hand thread on the chuck and probably no retaining screw. There may be a hole to insert a locking rod to prevent the shaft from turning as you attempt to loosen the chuck. Inserting the chuck key or a suitable substitute and gently tapping it with a hammer in the proper direction may be useful as well to free the chuck. A gummed up but not too badly rusted chuck can be rescued with penetrating oil like WD40 or Liquid Wrench: spray it into the chuck, let it sit for few minutes, then use the chuck key to start working it back and forth. Pretty soon it should be free - rotate through its entire range back and forth. Spray and spin a couple more times and it should be fine for another 20.000 holes.
Very inexpensive models (like the $30 Father's day specials) may use sleeve bearings in various locations instead of better quality longer lived ball or roller bearings. One particular bearing tends to deteriorate rapidly, especially if the drill is used for sanding or in dusty work environments (as opposed to clean rooms :-) ). This is the motor bearing at the handle end. The lubrication dries out or is absorbed by dust particles, the bearing runs dry, wears, and fails with an ear shattering squeal. Even if you use ear plugs, the speed and power are not adequate as the motor is laboring and overloaded and motor failure would result from prolonged operation. I have upgraded a couple of these drills to ball bearings. The substitution is straightforward requiring disassembly of the drill - removing of the front gear reducer and then one side of the case. At this point, the old sleeve bearing is easily freed from its mounting (just the plastic of the case) and pulled from the shaft. The shaft is likely undamaged unless you attempted to continue running the drill even after going deaf. The drills I upgraded had bearings that were 7/8" OD, 5/16" thick, and with a 5/16" ID center hole. The old ones were worn by almost 1/32" oversize for the center hole but the motor shaft was undamaged. I found suitable replacement double sealed ball bearings in my junk box but I would assume that they are fairly standard - possibly even available from Sears Parts as I bet they are used in the next model up. If the gear reducer needs to come apart to access the motor, take note of any spacer washers or other small parts so you can get them back in exactly the correct locations. Work in a clean area to avoid contaminating the grease packing. The bearing should be a press fit onto the shaft. Very light sanding of the shaft with 600 grit sandpaper may be needed - just enough so that the new bearing can be pressed on. Or, gently tap the center race with hammer (protected with a block of wood). Make sure that the bearing is snug when mounted so that the outer race cannot rotate - use layers of thin heat resistant plastic if needed to assure a tight fit (the old sleeve bearing was keyed but your new ball bearing probably won't have this feature). These drills now run as smoothly as Sears' much more expensive models.
Cordless drills use a permanent magnet DC motor operating off of a NiCd (usually) battery pack. Manufacturers make a big deal out of the voltage of the pack - 6, 7.2, 9.6, 12, 14, 18, etc. - but this really isn't a sure measure of power and time between charges as a motor can be designed for any reasonable voltage. A gear reducer follows the motor driving a chuck for holding the drill or screwdriver bit, or attachment. These are most often have a single or two speeds with reverse. In addition to the problems listed in the section: "AC line powered drills", these are also subject to all the maladies of battery operated appliances. Cordless tools are particularly vulnerable to battery failure since they are often use rapid charge (high current) techniques. * Bad NiCd batteries - reduced capacity or shorted cells. In most cases, a new pack will be required. * Bad power/speed selection/reversing switch. Replace. * Bad motor. These are usually permanent magnet brushed type motors. Worn brushes and bearings are common problems. In addition, a partially shorted motor due to commutator contamination is also possible - see the sections on PM DC motors. Disassembly, cleaning, and lubrication may be possible.
* Rotary (Moto) tools - high speed compact universal or PM motors with a variety of chucks and adapters for holding tiny bits, grinding stones, cutters, etc. * Routers, biscuit cutters - high speed (30,000 RPM typical) universal motor with a 1/4" (fixed size, router) chuck for common router bits. Ball bearings are used which have long life but are probably replaceable if they fail (noisy, excessive runout, etc.). The plug, cord, trigger, and interlock switches are prone to problems and should be checked if the tool doesn't run at all. * String trimmers - universal motor on long handle with trigger control. Check for a bad cord, switch, and dirt in the motor if the unit appears dead. The motor brushes could also be worn or not seating properly.
These use a universal motor which drives a gear reducer and reciprocating mechanism. Better models have a variable speed control so that the sawing rate can be optimized to the work. All but the most inexpensive allow the head to be rotated or rotate automatically based on feed direction adding a bit of complexity. A reciprocating saw is very similar but uses a much larger motor and beefier gearing. In addition to motor problems, there can be problems with damage, dirt, or need for lubrication of the reciprocating mechanism.
WARNING: Read and follow all safety instructions using any type of chain saw. These have a high power universal motor and gear reducer. Most have the motor mounted transversely with normal pinion type gears driving the chain sprocket. A few models have the motor mounted along the axis of the saw - I consider this less desirable as the gyroscopic character of the rotating motor armature may tend to twist the saw as it is tilted into the work. Inexpensive designs suffer from worn (plain) bearings, particularly at the end of the motor opposite the chain since this is exposed to the elements. Normal maintenance should probably include cleaning and oiling of this bearing. A loud chattering or squealing with loss of speed and power is an indication of a worn and/or dry bearing Replacement with a suitable ball bearing is also a possibility (see the section: "Upgrading the bearings on a Craftsman drill" since the approach is identical. Keep the chain sharp. This is both for cutting efficiency and safety. A dull chain will force you to exert more pressure than necessary increasing the chance of accidents. Chains can be sharpened by hand using a special round file and guide or an electric drill attachment. Alternatively, shops dealing in chain saws will usually have an inexpensive chain sharpening service which is well worth the cost if you are not equipped or not inclined to do it yourself. One key to long blade and bar life is the liberal use of the recommended chain oil. Inexpensive models may have a manual oiler requiring constant attention but automatic oilers are common. These are probably better - if they work. Make sure the oil passages are clear. The chain tension should be checked regularly - the chain should be free to move but not so loose that it can be pulled out of its track on the bar. This will need to snugged up from time-to-time by loosening the bar fastening nuts, turning the adjustment screw, then retightening the nuts securely. There may be a slip clutch on the drive sprocket to protect the motor if the chain gets stuck in a log. After a while, this may loosen resulting in excessive slippage or the chain stopping even under normal conditions. The slip clutch can generally be tightened with a screwdriver or wrench.
These have a high power universal motor either directly driving the blade or driving a gear reducer (high torque/large blade variety). Miter and cutoff saws are similar but are mounted on a tilting mechanism with accurate alignment guides (laser lights in the most expensive!).
A dual shaft induction motor drives rotating grinding stones (or other tools like wire brushes). Most common are fixed speed - usually around 3450 RPM but variable speed operation is highly desirable to avoid overheating of tempered metal during sharpening. All but the most inexpensive use sealed ball bearings requiring no routine maintenance. Small light duty grinders may be 1/4 HP or less. However, this is adequate for many home uses. Wet wheels may run at much slower speeds to keep heat to a minimum. Being in close proximity to water may in itself create problems.
A gear reduced universal motor drives a rubber (usually) mounting plate to which a sanding disk or polishing pad is attached. Due to the nature of their use, sanders in particular may accumulate a lot of dust and require frequent cleaning and lubrication.
In addition to the usual universal motor and its bearings, the orbital mechanism may require cleaning and greasing periodically.
A typical portable belt sander uses a gear or belt reduced universal motor driving one of the rollers that the sanding belt rotates on under tension. In decent quality tools, these should use ball or roller bearings which require little attention. A power planer is similar in many ways but the motor drives a set of cutters rather than a sanding belt.
A direct or belt drive induction motor (probably capacitor start) powers a single or multiple cylinder piston type compressor. Typical continuous motor ratings are between 1/4 and 2 HP (for a 115 VAC line). Over and under pressure switches are used to maintain the pressure in an attached storage tank within useful - and safe - limits. Most will include an unloading valve to remove pressure on the pistons when the compressor stops so that it can be easily restarted without damage to the motor and without blowing fuses or tripping circuit breakers. I much prefer a belt driven compressor to a direct drive unit. One reason is that a motor failure does not render the entire compressor useless as any standard motor can be substituted. The direct drive motor may be a custom unit and locating a replacement cheaply may be difficult. Drain the water that collects in the tank after each use. Inspect the tank regularly for serious rust or corrosion which could result in an explosion hazard.as well.
Traditional air powered paint sprayers may simply be an attachment to an air compressor or may be a self contained unit with the compressor built in. Since the active material is paint which dries into a hard mass (what a concept!), cleaning immediately after use is essential. Otherwise, strong solvents will be needed to resurrect a congealed mess - check your user's manual for acceptable deadly chemicals. Portable airless paint sprayers use a solenoid-piston mechanism inside the spray head itself. There is little to go wrong electrically other than the trigger switch as long as it is cleaned after use. Professional airless paint sprayers use a hydraulic pump to force the paint through a narrow orifice at extremely high pressure like 1000 psi. With all types, follow the manufacturer's recommendations as to type and thickness of paint as well as the care and maintenance before and after use and for storage. Warning: high performance paint sprayers in particular may be a safety hazard should you put your finger close to the output orifice accidentally. The pressures involved could be sufficient to inject paint - and anything else in the stream - through the skin resulting in serious infection or worse.
These are similar to high performance hair dryers and subject to the same problems - bad cord or switch, open heating element, defective thermostats, universal motor problems, and just plain dirt and dust buildup.
These are just a high power heating element attached to a cord. If there is no heat, check for a bad plug, cord, or open element with your multimeter.
Simple pencil irons use an enclosed heating element is attached to the 'business' end in some manner - screw thread, set screw, clamping ring, etc. Failure to heat may be due to a bad plug, cord, bad connections, or defective element. Some types package the heating element and replaceable tip in a separate screw-in assembly. These are easily interchangeable to select the appropriate wattage for the job. Damage is possible to their ceramic insulator should one be dropped or just from constant use. High quality temperature controlled soldering stations incorporate some type of thermostatic control - possibly even with a digital readout.
The common Weller Dual Heat soldering gun is a simple transformer with the tapped primary winding in the bulk of the case and a single turn secondary capable of 100 or more amps at around 1.5 V. The soldering element is simply a piece of copper (possible with a shaped tip) which is heated due to the high current passing through it even though it is made mostly of copper. The 'headlight(s)' (flashlight bulbs) operate off of a winding on the transformer as well. Possible problems include: * No response to trigger - bad cord, bad switch, open transformer primary. * Low or high (dual heat models) does not work - bad switch, bad transformer primary. * Lack of sufficient heat - bad connections where soldering element mounts. clean and/or tighten. Tin the tip if needed (not permanently tinned). Use the high setting (dual heat models). * Tip too hot - use the lower setting (if dual heat). Do not keep the trigger depressed for more than 30 seconds or so at a time. Manually pulse width modulate the power level. * Entire unit overheats - this could be a shorted winding in the transformer but more likely is that you are simply not giving it a chance to cool. It is not designed for continuous operation - something like 2 minutes on, 5 minutes off, is usually recommended. * No light - bad bulbs, bad connections, bad winding (unlikely). Note: a soldering gun is not a precision instrument and should not be used for fine electronics work - you will ruin ICs and printed circuit boards. (However, I have heard of someone replacing an MC68000 microprocessor (64 pin DIP) successfully with a large Weller soldering gun!)
A powerful universal motor driving a centrifugal blower is all there is in this equipment. Unfortunately, many common models use cheaply made motors which may fail simply due to use or from the dust and proximity to liquids. The blower sucks air and whatever else into the holding tank. A filter is supposed to prevent anything from getting through. The motor itself should be sealed against direct contact with the dust/liquid section of the machine. Problems occur with bad cords, switch, motor brushes, bearings, or a burnt out motor from excessive use under adverse conditions. As with inexpensive electric drills, sleeve bearings (usually, the top bearing which is exposed somewhat) in the motor can become worn or dry. Replacing with a ball bearing is a worthwhile - but rather involved - undertaking if this happens. See the section: "Upgrading the bearings on a Craftsman drill" as the technique is similar (once you gain access - not usually a 10 minute job).
A gear reduced universal motor drives a reciprocating mechanism not too dissimilar to a saber saw. In addition to the usual motor/electrical problems, lubrication may be needed periodically. Should you accidentally try to trim a steel fence instead of a bush, damage to one or more teeth may occur. In this case, light filing may be needed to remove nicks and burrs. Of course, you probably will not get away without cutting the power cord a couple of times as well! See the sections on power cords. One way to avoid the humiliation (other than being half awake) is to wrap a cord protector around the first 2 or 3 feet of cord at the tool. This will make the cord larger in diameter than the inter-tooth spacing preventing accidental 'chewups'.
A large universal or permanent magnet DC motor drives one or two sets of rotating blades. A load or dead short may be thrown across the motor to act as a dynamic brake when stopping. As usual, when the mower does not operate, check for bad plug, cord, switch, brushes, dirt, etc. See the sections on motors.Go to [Next] segment
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