You have an electric motor designed to run under AC, but it does not run. What can you do by yourself? This instruction manual involves a series of simple and logical steps for the classification procedure for the capacitor to start the motor to run again. I\'m assuming you have a single-phase motor of 1/4 or 1/2 hp, maybe even up to 1 hp. It may have a capacitor, but it may also have two. The design of the motor can be either a capacitor start or a capacitor run. You will find these types of motors in most home and workshop applications. Special motor for industry (Three-phase DC) I still know nothing about them. The most common cause of HVAC failures in hot summer is motor capacitors. ( Your air conditioner is not running, just buzzing. ) Knowing this, you can use what you found in this manual to check your system and even replace the capacitor before it fails. Note: This Instructure is written to share some of the useful things I \'ve learned and some of the tools and resources you\'ll find helpful. The purpose is to give readers enough help to do some careful testing and solve some basic problems. Please don\'t let me diagnose your motor from a distance and tell you how to fix it. I do not have the conditions to do so. Buy the same book as I bought (see step 6) Find some articles on the Internet and watch some videos. Then do some careful testing in logical order. Say it out. Be prepared to give up your assumptions. Be patient. You can also get your motor running again. Materials-Tools- Turn the motor shaft by hand. Can it turn freely? There will always be a little resistance, but the shaft should rotate relatively freely. Still, the old motor may have dry grease bearings. If there is no rust inside the bearing, you may apply new grease inside. And greatly improved. I sometimes gently pry the bearing seal on one side, apply some bearing grease in it, eliminate any damage to the bearing seal, and then re-tap it in place. This is not a recommended procedure, but I think it works with motors that are used occasionally in my workshop. The bearing can also be a bronze sleeve bearing. In the worst case, you may need to go to the bearing store to buy a match for a ball bearing that is stuck badly, but these are not cheap. Hopefully your car will run like a new one and it doesn\'t cost much. What happens when you power the motor? Hope there is no spark or impact on the motor frame and the circuit breaker will not trip immediately. If you have any of these things, look in the power cord for worn wires that come into contact with another worn or worn wires that short-circuit to the iron frame of the motor. It takes only a few seconds to power up. The coil winding inside the motor quickly heats up on the motor that is not running, and the coil may be destroyed. The motor will then need to be restarted to work again. When you increase your power, it is very likely that the motor will make a roaring noise. The start winding may also not work properly, but there may be more than one reason for this. The drawing shows the circuit diagram of this type of motor. The start winding part is only powered on for a few seconds. The centrifugal switch then locks the part of the starting winding circuit. In the next steps, tests will be conducted to eliminate possible causes. The second photo shows the operation of the motor when connected to the AC ammeter. The nameplate on the motor shows that its current is 7. 3 Amps. The meter is set to 15 Am p. range. The actual reading is slightly below 7 amps. When the motor is actually running, it is confirmed that everything is normal by accepting such a reading. This photo was taken after the motor was fully functioning. An early reading when the start winding is not working because it should fix the needle, which also indicates a problem. Unplug the motor from the power supply. Access the connection between the power cord and the motor winding. If there is a junction box cover plate, please remove it. ( Make some photos that show the connections so you can make them correctly again if you need to take them apart. ) If there is no junction box on the motor, remove the power cord to connect to the motor end of the winding. Also, bridge the two terminals of the capacitor with a screwdriver to remove any charge that might shock you. Remove the wire from one side of the capacitor to prevent false readings caused by current passing through the reverse channel. With ohrazer. Many people recommend setting it around 2000 ohms. Connect a lead to the iron frame of the motor. Connect the other lead to each wire issued from the motor, including the one connected to the capacitor. Open circuit should be indicated for all readings ( Channel without electricity). If any reading indicates a path to power up, please check carefully to make sure you get the exact reading. If you still find evidence of the power-on path, one of the windings will short-circuit to the motor frame. This may indicate that the motor needs to be restarted. But do a visual check first to check for a simpler explanation. Once, when I plugged into the rotor, I hooked a thin enameled wire from one of the windings. The wire was scratched to expose it in one place. It is then pushed near the iron frame of the motor, short circuit and show the leakage path. I can coat the wire with an insulating liquid and push it away. You checked the shorts. Open the check now. Follow the wires as much as you can. The start winding uses wires that are thinner than the running winding. Use ohrazer to check if the two windings are broken. The resistance on each winding will be relatively low, but the resistance on the starting winding will be slightly higher. If one of the windings shows an open circuit, observe carefully where the wire is connected to the terminal or the heavier wire. This connection is the most common place where open connections occur. ( I used to fix a \"dead\" Dremel tool. There is no indication that there is an open circuit in any of the coils. However, the field coil shows an open circuit between the two terminal pins. I took a closer look and saw that the coil line attached to one of the terminal pins broke. I did my best to scrape the enamel off the wire and made a welding bridge on the terminal pin. It\'s not a perfect solder joint, but Dremel is working again. ) If you can\'t find a break in the coil circuit and fix it, the motor needs to be re-wound. Check with ohrazer to determine the power supply provided by the high temperature protection reset and the electrical path through it, and it will not be damaged, thus opening the circuit and keeping the motor out of operation. The capacitor start motor uses the start coil and the capacitor to generate a forward magnetic field in the stator ( Motor outer frame with Coil). This forward magnetic field gives the rotor something to chase, causing the rotor to rotate. ( For example, put a bar magnet on a glass table. Take another bar magnet from under the table. Move the magnet under the table. The magnet above the table chase the magnet below the table in the rough form of the motor. The magnetic field moving forward in the stator replaces the movement of your hand under the table. ) If the start coil remains energized in the circuit for more than a few seconds, it will be destroyed. After most motors have established most of the speed on the motor shaft, the start winding is disconnected from the circuit using a centrifugal switch. See the first graphic. Because the centrifugal switch is in the position inside the motor, it is not possible to take pictures on all its components, so I made a side view drawing showing the part relationship. See text box. If the centrifugal switch is working properly, it usually presents a closed loop. In the fully assembled old motor, the contact of the switch may be pitted and burned, or its components may be worn out, so that there is not enough pressure to close the contacts when the motor is not running or when it is first started. Watch your motor carefully and find the wires that lead to the fixed switch contacts. ( One can go to the capacitor, one can be on the pillar of the junction box. ) Connect ohrazer to the contact wire. Is there an electrical path indication through the switch contacts? If not, turn on the motor and try to clean and polish both by dragging some very fine sandpaper through the contact point. If the switch is worn out, the plastic wire shaft on the motor shaft may not apply sufficient pressure on the plate that keeps the contact fully closed. Look at the second photo. I tested my switch contacts with a fully assembled motor. I insert the screwdriver through the opening at the front of the motor and gently apply a little pressure to the end of the shaft ( Away from motor) Turn off the contacts when connected to ohrazer. Make sure the end position of the rotor is correctto- Motor end. If the gasket has space, the thrust gasket can be used to move it slightly. ) I made a different gasket with the No. 16 steel plate to fit at the end of the wire shaft. The contacts on my motor are now off and the motor is running. But I also want to weld labels on it that fold the end of the online shaft, so I\'m sure the gasket will shrink when the centrifugal weight pulls the wire shaft away from the fixed contact I don\'t want the washing machine to float into the contacts and accidentally turn them off while the motor is running. This can overheat and destroy the Start winding. ( I looked at my book again [See step 6. ]. Another option is to place the gasket under the fixed part of the centrifugal switch to make it closer to the line shaft. ) Although the new fixed part of the centrifugal switch is not exactly the same, it is also possible to purchase. I don\'t see any list anywhere. It is also possible to purchase an electronic switch to replace the centrifugal switch. The electronic switch does not respond to the speed of the motor shaft as the centrifugal switch does, but is disconnected from time to time. It allows the Start winding to engage 7. 4 seconds, then disconnect the circuit. The price of electronic switches is slightly higher than $40. After 20 years or less, it is not uncommon for electrolytic capacitors to dry and fail in audio equipment. However, if the capacitor is not your real problem, replacing the START capacitor, open reset and faulty centrifugal switch without first checking the short circuit or open winding will not make your motor run. Many motors have a dome cover on the outside of the motor and the capacitor is under it. The Motor capacitor is usually a cylinder with terminals on the top. However, some capacitors in the old motor may also be flat, such as a bunch of 4x6 Lead Cards. These may be located at the bottom of the motor, so it looks like the motor does not have a capacitor. It may swell or leak when the capacitor fails. It may even crack. But it looks normal. There are a variety of test procedures for capacitors, but these tests are not foolproof. The capacitor can pass several tests but still fails under load. If you have not already done so, use a screwdriver to cut off any remaining charge in the motor capacitor. Do this several times for the sake of safety. If your capacitor does need to be replaced, please copy the voltage and capacitance numbers and hopefully it will still be visible clearly. You can always use a replacement capacitor with a rated voltage higher than the original capacitor of the motor, but the capacitance number should match as much as possible. Therefore, the 230 v ac capacitor can be replaced by the 125 v ac capacitor. The capacitance will give a range, such as 220 micro-farad to 260 micro-farad. Capacitors with a rated capacity of 210 micro farad to 250 micro farad should be close enough to function properly. ( If you see a rating in millifarads, 1 millifarad equals 1000 microfarad. ) Here are some ways to test the capacitor. Choose something that suits your existing. Procedure A-- Remove at least one wire from the capacitor, while the motor circuit does not have a power supply, connect one ohrazer on both terminals of the capacitor. Analog meters are preferred but not mandatory. The reading should rise to a high number and suddenly drop to zero or open. If there is a stable reading of a certain value, the capacitor is short-circuited. If the reading does not rise initially, something inside the capacitor is broken and there is an open circuit. Procedure B-- Remove two wires from the capacitor. Connect it to the lamp line and connect it in series with an incandescent lamp of approximately 60 watts. Connect it to a wall socket. Although it may be darker than usual, the light bulb should be lit. Procedure C-- You can get a capacitance value of 1 m here for less than $20. The above test let you know if the capacitor is working but did not give you a hint about the actual capacitor of the capacitor. ( The dry electrolytic capacitor may look good, but its capacitance is too low to start the motor. ) 1 m change. Search instructions for capacitor meter circuits. At least one uses the Arduino module. About 25 years ago, I had an electronic magazine with a homemade circuit based on a 555 integrated circuit capacitor meter. ( This is a similar device that you can do. ) I now have a digital multimeter with a capacitor reading. Some capacitive meters use high-frequency signal generators that are part of the meter. These can be used \"in the circuit\" and give accurate readings without feedback from other parts of the circuit. The capacitor can give a good reading on 1 m but still weak or fail. The ESR meter measures the internal resistance that affects the actual performance. Procedure C\'-- The book mentioned next provides another test. It includes measuring current (amperage) When the motor is powered on, it is used by the motor. Given the parameters of the test, a mathematical formula tells you how many micromethods the capacitor produces. Because this is a test under load, it is very helpful. Procedure D-- It is not always feasible to buy a few test devices and you may not use them more than once or twice. If all else ( Short circuit and open, centrifugal switch, reset, etc. ) Check your motor and the capacitor shows it should be good but the motor is still not running and a new capacitor is shipped to your door for $10 to $20. The worst case scenario is that you\'re going to make a relatively small amount of money, which may be that your capacitor has a defect that doesn\'t show up in the tests you\'re able to do. In the best case, the motor may run. Upon completion, restore the connection to the capacitor, old or new. I looked at the price and the content description before deciding to buy the book. ( I don\'t have any benefit if you buy this book, nor do any of my friends or relatives. ) Very helpful. I went on to say that something was not detailed enough for me Look for additional materials or videos on YouTube. The book is now soaked with ink on my underwear and edge notes. I bought this book because some people I know think I know enough to help them solve the motor problem. I have shown the 61 year old 1/2 hp craftsman single phase capacitor start motor in many photos. ( There\'s a 10 56 [October 1956] Seal the motor board. ) It worked when I bought it in a used tool sale about two years ago, but when the shaft was turned by hand, the ball bearing sounded rough. I turn on the motor and pack the bearing with new grease. I did my best to level the seals and put them back in place. There are a lot of fine sawdust inside the motor. I cleaned it up. When turning by hand without power, the motor shaft rotates freely and smoothly. When I assembled the motor and powered it on, the shaft turned about 1/8, froze and growled. I checked the shorts and turned on but the coil was fine. I always doubt the old capacitor, which is 61 years old. I did several tests on the capacitor. It passed each and every one of them. I\'m still pretty sure the capacitor is faulty. I slept on this question. I realized I assumed the centrifugal switch was working fine. I Oil heavy objects and let them move freely. I cleaned it, so the axis of the line can slide freely. When I connected the ohrazer to the wire attached to the fixed part of the centrifugal switch, the contact point did not provide an electrical path, although I had cleaned and polished them with fine sandpaper. I insert the screwdriver from the front of the fully assembled motor at a certain angle. I can push the contact plate slightly with a screwdriver. All of a sudden, a good circuit was shown by my ohrazer. I saw a couple of Wear points on the contact plate and the wire shaft rubbed on it. I made a gasket as a spacer between the contact plate and the wire shaft. My motor purrs like a contented kitten. However, when the motor is running, the washing machine can move to apply pressure to the centrifugal switch contacts and engage the Start winding. This may cause the Start winding to burn out. I checked my book and the other option was to add a gasket between the motor frame and the fixed part of the centrifugal switch. I finally did this and each mounting screw uses a normal washer and I remove the one I made. 61 years later, there were several cracks in the rubber-covered wires. I bought a new wire. The old wire is two wires. I bought three wires to connect the ground wire to the motor frame to meet today\'s standards. . I have quite a bit of experience with home wiring in most of my life, but the motor is still a mystery beyond a very basic understanding. The book I bought filled the gap. I am now aware that some logical basic testing and thoughtful inferences will help me to solve the basic motor problem I would expect to see.
