How to Test a Drill Armature with a Multimeter

Checking the Armature for Shortcircuits

Electrical machines consist of a rotor and a stator. The stator is the stationary windings in the housing. the armature is a moving part, so it usually gets dirty and grease particles and gets oxidized by the temperature. It can cause malfunction or failure of the rotor of an electric machine. It is detected by visual inspection. Carbon deposits may cause inter-turn short circuits in the armature. As such, the rotor of an electric motor will not wear out under normal operating conditions. Over time, only the current brushes must be replaced if their length is no longer within the allowable size. However, prolonged stress causes the stator windings to become hot, resulting in the formation of carbon deposits. An armature can be short-circuited if it is mechanically damaged. Chips, dents, scratches, and cracks on rubbing surfaces are unacceptable. Short-circuiting between the windings of the armature occurs when the bearing assemblies fail. Then the armature becomes misaligned and the armature breaks its lamellae. Another cause of short circuit is exposure to moisture. Corrosion occurs when water droplets hit metal surfaces. Rust makes it difficult for the armature to rotate, current loads increase, it heats up and the solder may flake off, which in turn can cause an inter-turn short circuit if operated for long periods of time.

It is possible to diagnose this fault at home. Carry out this procedure with the help of an inductance coil, called a choke.

With this device, you can find out the direction of reset, and the order in which the winding coils are connected to the collector lamellae.

This is how you check the armature for inter-turn faults.

To make such a device with your own hands is not difficult, just familiarize yourself with our step-by-step instructions.

To assemble the device. You will need a U-shaped transformer iron. It can be removed from the vibrating pump type Malysh.

We disassemble the construction and take out the U-shaped transformer iron.To do this, you must first heat the bottom of the pump. so that the polymer with which the coils are filled will melt.

Next, using a handy tool, cut the edges on the transformer iron, as shown in the photo. During the processing, remember that the iron is puffed, so you must perform all operations carefully to avoid burrs. After that we will remove all sharp edges on the product with an emery machine. This is necessary to maintain the integrity of the enamel wire.

It is not necessary to follow the strict dimensions of the corners, the main thing is that the anchors of different sizes can easily be placed in the prepared place.

Armature testing on starter

The next step is to make the coils. To increase the size of the device and to make the choke not too bulky, we make not one but two coils, which we place on both sides of the U-shaped iron. For this we will need:

Measure all the dimensions of the U-shaped transformer iron to their maximum values. Then we transfer them to cardboard and draw a scroll of the body of the future coil. At the same time it is necessary to take into account the size of the groove of the core. Next, use the blunt end of the scissors to draw all the lines of inflection. This will help bend the cardboard without any problems. We cut a reamer. We do the pattern on the other side in the same way. Now we need to prepare the covers for the coils. We will need 8 of them. Let’s mark the covers on the cardboard. Cut out the outer contour with scissors, the inner one with a sharp knife.

Next, we glue the covers with the prepared reamers and get two frames of the future coils.

Now you need to wind the wire on the coils. For this we use the calculation of the transformer. First determine the cross-sectional area of the core by multiplying its length and width. In our case the area was 3.7 cm x 2.2 cm = 8.14 cm 2. Then we divide 13200/8,14 = 1621 turns. We round up this number to 1700 turns and distribute it equally between the two coils, we get 850 turns each. This amount can be wound by hand without any problem. An error of 20-40 turns will not affect the result. But it is better to err on the side of increase. Before you start winding, it is necessary to make the holes where the wire ends will come out. A heat shrink tube should be placed over the free end of the wire. The wire end is inserted into the hole and then the winding process begins. At its other end, solder the wire with the shrink tube and put it into another hole. Wind the second spool in exactly the same way.

Once. both coils are ready. put them on the U-shaped core. the leads must be placed on one side at the bottom. It is important. so that the coils are wound identically. the coils are wound in the same direction. and their ends point in the same direction. The next step is to connect the induction coils and apply mains voltage (220V) to their ends.

The device of an electric drill

The power drill consists of two interconnected parts: the mechanical and electrical. Understand the structure and principle of operation is easier if you consider these two components separately.

The modern drill consists of several nodes, each of which refers to a mechanical or electrical system

Electric part

The basis of the electric drill drive is the electric current, which comes into the tool through the power cord from the household electrical grid. It operates a motor (usually of the collector type) located inside the central part of the housing. The electric motor consists of two elements:

  • of the stator. It is made of electrical steel with high magnetic permeability. The windings. coils of copper wire, which induce a magnetic field of. The stator is rigidly mounted in the body of the tool;
  • of the rotor. In contrast to the stator, it rotates on support bearings. The rotor is the operating shaft on which the counter windings are mounted. The armature rotation is due to the electromagnetic interaction of the frames (windings) laid in specially shaped grooves. At the tail end of the armature there is a collector that serves the function of distributing the current to the windings. This is caused directly by the graphite brushes that are energized by the mains. Continuous contact of the brushes with the armature collector is maintained by springs pushing on the graphite (or carbon) electrode. The rotary motion of the motor rotor is transmitted to the chuck holding the drill bit or other work tool.

Turning modes are controlled by a trigger located between the motor and the power cord. A speed control wheel and reverse switch are built into (or above) the button. Variable voltage triac circuitry is used in the rotor speed control for ease of operation. Thanks to microfilm technology, the regulator is so small that it can be built into the trigger of the button.

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A speed regulator is built into the button and can be controlled with a surface-mounted wheel

Reversing switch for reversing the direction of movement of the motor has two positions. One corresponds to the clockwise movement (basic mode). The other corresponds to the counterclockwise movement of the shaft, which is used when unscrewing screws or when jamming a drill. The reverse connection diagram of an electric drill is usually shown on the machine itself.

The reversing connection diagram is shown on the housing

To shield the motor from mains disturbances and to quench the inverse EMF (electromotive force), a capacitor is installed on the brushes at the input of the circuit. It is usually located at the bottom of the drill handle next to the power cord inlet.

In some models, induction rings are installed to smooth out the frequency components.

The induction ring smoothes out current pulsations by inducing a magnetic field

Mechanical part

The job of an electric drill is to rotate the power tool. The chuck, which can be a cam, quick-action chuck or tapered chuck, is used for this.

The quick-change chuck makes it possible to change the operating tool in a few seconds without using a wrench

Direct transmission of rotation from the motor to the chuck by the gearbox. Its main task is to reduce the speed of the electric motor, because the latter develops speed up to several tens of thousands of revolutions per minute. The planetary worm gear does the trick. Simultaneously with the lowering of the rotational speed, the rotational power is increased. There are drills, in which along with smooth speeds there are also fixed speeds, usually two. The operation of the speed selector is similar to that of a car gearbox.

The first electric drills appeared in the middle of the XIX century. This is due to the invention of the electric motor and its mass production. They became an independent tool in factories and on ships in the 1980s. An electric drill became widespread in daily use only at the end of the XX century.

Those drills that are equipped with a chisel function have an additional ratchet mechanism. With its help, the progressive-return movement of the chuck is carried out, which can be regarded as a percussive mechanism. When the ratchet teeth jump, vibration is generated, which is used when working with concrete, brick and stone. Wood and metal parts are machined without this mode. The “ratchet” is activated by a special button located on the housing.

test, drill, armature, multimeter

The impact mode of the drill is activated by turning a special switch to the position indicated by the hammer

In fact, the percussion system consists of two corrugated surfaces mounted on a work roll. In normal operation, they do not participate in the drilling process, they are separated by a spring. But when they come into contact and rub against each other under the action of the switch, there is additional vibration. The drill bit has to be suitable for such work. usually the tool is used with a reinforced cutting edge, pobedite, etc. д.

Disassembling a power tool

Anyway, if there is nothing wrong with the brushes, you can’t do without disassembling the tool. At this point, the most important thing is not to do more damage. Particular attention should be paid to the correct selection of screwdrivers, as damaged screws will be difficult to unscrew, and the check will turn into excruciating locksmithing. Some power tools use different length fasteners. Their location should be noted down (or better yet, written down or sketched out).

In order to successfully assemble the power tool after its diagnosis and repair, we recommend that beginners take pictures of each step of the disassembly. It’s a great help if you forget which part was in place before the test.

How to check the stator of an angle grinder. causes of failure, tools for checking

The stator is the stationary part of the electric motor, designed to create the electromagnetic field in which the rotor (the moving part of the motor) rotates. Possible causes of angle grinder failure include breakage or short circuit of the stator winding (coil).

Possible causes

Factors that cause the stator to malfunction

Signs by which you can recognize that the stator is malfunctioning:

  • Smells like burning insulation.
  • The housing overheats.
  • Smoke appears.
  • Shaft rotation slows down or stops.
  • Spontaneous shaft unwinding, tool suddenly reaches maximum speed.

The winding wires are coated with a protective layer of insulating varnish. Overheating causes the stator to burn out and damage itself. It causes the turns to short-circuit. Varnish gives off a peculiar odor. A short circuit in just one of the wires completely takes out the angle grinder.

Rules to avoid overheating of the angle grinder motor:

How to Check the Armature good or damaged.(Tagalog)

  • Switch off the device after working at reduced speed, not immediately, but after about one minute.
  • Take frequent breaks when working under load at lower speeds.

It is often possible to prevent the replacement of a defective stator by rewinding the. Rewinding of a damaged stator coil of the angle grinder can be done by your own hands, but it is still recommended to entrust this work to a specialist.

Checking with a short-circuit indicator

A winding breakage or short circuit in the winding can be detected with the short-circuit indicator (IR). Other names for inter-turn short circuit indicator or electrical machine winding defect indicator.

  • of the power supply;
  • housing with an LCD display, sockets for connecting accessories;
  • of the connecting wires;
  • Large inductance sensor;
  • Small inductive sensor.

The principle of operation of the indicator is based on the induction of pulse electromotive force in the winding under test. In the presence of short-circuited turns the magnetic field impulse from the short circuit current flowing through them is registered.

The procedure of testing the stator of angle grinder by the device IDVI:

  • Inspect the inter-turn fault indicator. Make sure that there is no external damage and that the connection wires and sensors are intact.
  • Connect the power supply.
  • Press the power button and make sure the unit is in good working order.
  • If the winding defect indicator has been out in the cold for a long time, it must be kept at room temperature for at least 2 hours.
  • Disconnect power to the angle grinder.
  • Select from two sensors large or small, depending on the size of the stator.
  • If the angle grinder’s data sheet does not specify the rated voltage per coil of the winding, it must be determined by the formula: The rated voltage of the entire coil divided by the number of turns.
  • Turn on the unit.
  • Set the pulse test voltage amplitude on the indicator to a value larger than that obtained in the calculation.
  • Hold the sensor against the winding surface and check all the slots one after the other, waiting 3-4 seconds. If a short circuit is detected, the instrument will beep and the corresponding inscription will appear on the display.
  • If no short-circuited turns are found, set the next higher amplitude on the meter and make sure that there is an insulation safety margin for the winding.
  • Turn off the unit.

With a winding fault indicator you can check the insulation condition between the stator and rotor coils as well as between the stator winding and the angle grinder’s body. If you can not buy a ready-made device, you can make a simpler indicator of short circuits yourself.

Checking with a multimeter

To confirm that the stator is in good condition, use a multimeter. This is a universal measuring device. It can measure several electrical quantities: voltage, current, resistance.

The device consists of a housing with a display, a switch, and sockets, and two cords with probes (plus and minus).

always connect the minus probe to the bottom socket and the plus probe to the middle or top socket, depending on the current in the tested device.

test, drill, armature, multimeter

To check the stator of the angle grinder (angle grinder), you need to set the multimeter to a resistance value of 20 to 200 ohms and take turns to bring the feelers of the measuring device to the windings. If the resistance is the same everywhere, then the coil is in good order.

If the meter shows a different resistance at some points, then there is a short circuit or breakage of one of the coils in the winding. Check the stator using an ohmmeter following the same principle.

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It differs from a multimeter only in that it can only measure resistance.

Test device for checking armatures and stators of electric machines

Another device with which you can verify the stator of angle grinder. device for verification of armatures and stators of electric machines PUNS 5. The device has a light and sound alarms, allows to detect winding short circuits, open circuit, measure the insulation resistance of coils.

The device operates in two modes. “armature” and “stator. Mode change is made with a switch. The device is equipped with a handy tool for mounting and fixing the tested motor. It consists of two legs attached to the shaft.

The jaws move freely along the shaft, allowing you to change the distance between them and check motors of different sizes. Checking is carried out with two feeler gauges. The presence of breakage or short circuit on the stator winding is indicated by special red LEDs and sound signal.

details about the checking procedure are described in the instruction manual of the device.

It is relatively easy to check the stator of an angle grinder thoroughly. But this can be done only with the help of special devices. Therefore, if visual inspection confirms that the angle grinder failure is due to a damaged stator, further testing and repair is better performed in a specialized workshop.

How to check the serviceability, ring the rotor angle grinder at home, video

In a domestic environment, there are the following ways to diagnose an armature:

  • visual inspection;
  • Using a multimeter;
  • light bulb and two wires connected to it;
  • By means of machines designed specifically for inspecting the integrity of the windings (short-circuit indicator, armature checker, etc.).

For more information on types of diagnostics, see the information below, which has a video.

Visual inspection

Even with a full arsenal of tools to check the armature circuit, never neglect a visual inspection, the indispensable first step in the entire diagnostic process. A keen eye will find indications that a user familiar with rotor design and operating principles would be able to identify the nature of faults.Charred marks and specific smell cause burned insulation and eventually damage to the winding wires. Pay attention to crumpled or swollen coils, which can sanction the presence of breaks in this place. On the windings there may be particles from the solder, which is source of short circuit.

Disturbances of winding contacts with the collector can be detected by burned out lamellae. Visually diagnose damage to the collector itself. raised, worn or burned plates.

With a tester, multimeter

Multimeter or other tester to measure electrical parameters: current, voltage, resistance. can be used to find breaks in the winding wires or breakdowns on the core body.

In the following video the author offers a variant of diagnostics from simple to complex. First of all the stator is tested with a multimeter. It is much easier to check than the rotor. If there are no breaks or breaks in the winding on the stator to the housing, then you can conclude that the armature is defective. Then it is necessary to carry out its diagnostics in more detail with determining the exact type of defect and defining the method of elimination. The multimeter is tested in the “resistance test” mode with the set minimum measuring scale (up to 200 Ohm).

In this video, as in the other shows the process of determining winding breaks, which is really quite time-consuming, since measurements are made between each pair of lamellae on the entire contour of the collector. In this case, if the armature has no open windings, all the multimeter readings should not differ from each other within 0.1 ohm. The breakdown of the windings on the body is much easier to check by placing one probe on the body of the core and the other on the plates of the collector. The scale of the multimeter should not react with any readings.

How to check (ring) the starter armature at home. The Automaster

Some men can find problems and faults with their own hands, and repair and replace necessary parts. This article with instructions will be useful for those who are ready to repair your car. And for those who value their time and want to save money, we recommend turning to professionals. Our company works seven days a week, and our will make you happy.

We offer services starter armature wire tapping in Minsk qualitatively and quickly at any time. We have modern equipment with the help of which our professionals will quickly and accurately determine the problems and malfunctions of your car. We work with almost all brands of cars such as: BMW, Toyota, Mitsubishi, Audi, Volkswagen, Mazda, Nissan, Opel and many others.

Diagnostics and check the starter

If you are on the highway far from the service, you need to know how to remove the starter and diagnose the problem with their own hands. You can make a diagnosis visually and with the help of a multimeter. Visual inspection will tell you if there are any chips, cracks. these must be repaired. Next you need to check the starter armature.

How to test starter armature with a multimeter will tell you in this article. If you can not test it yourself, we can help you check the starter armature with a multimeter.

Starter repair begins with disassembly of motor armature. Causes of malfunction may be:

  • Loss of contacts on the terminals.
  • Worn or broken brushes.
  • High temperatures for the collector plates.
  • Poor insulation.
  • Short circuit between the plates.
  • Intertwin Fault.
  • Armature jamming in the snout.

The first signs of starter malfunction:

  • A characteristic humming sound;
  • Vibration during starter operation
  • Appearance of sparks;
  • Strong heating of the body and the appearance of an unpleasant smell of burned plastic;
  • Anchor rotation.


The most common problem is a short circuit. Problem solving. visual diagnosis of the inca outputs and wiring. Then you need to clean the contacts and make a diagnosis with a multimeter. Glue the damaged area.

How to diagnose the problem and repair the starter

If you can not visually identify the place where the breakdown of the wire, you can close the wire at the junction of all the lamellae and apply voltage. In the place where it burns out. the breakdown. Also pay attention to the condition of the lamellae. If they are damaged and can be repaired, it is necessary to repair the lamellae.

Rotor winding of the starter is also checked with a light bulb. We put the lamp starter to the manifold plate and see if the bulb lights up or not. If it lights up, the winding needs to be replaced or the rotor needs to be completely replaced. If it does not light up, check the resistance with an ohmmeter. The resistance should be small, about 10 kohms.

If there is an inter-turn short circuit, the device for checking the starter armature will help determine it. The decision of a problem will be the correction and alignment of all wires and cleaning them from debris.

If the above methods do not help, rewinding the armature will.

Repair the armature with your own hands begin with the removal of the short circuit, be sure to clean the place of the short circuit and check whether it reappears.

When soldering the collector leads, remove the rotor and clean the surfaces well with a drill, solder them and check for intercircuit.

To determine the burned out armature is necessary to use the battery.

Frequency of starter diagnostics

Depending on the load on the starter will depend on its wear, respectively, the greater the load, the more often you need to diagnose the starter. Don’t forget to diagnose and repair car malfunctions in time.

Now you know step by step how to check the starter at home. Order diagnosis and repair the starter car you can in our company Modnikov. Good luck on the roads!

How to check the serviceability and perform repair of the angle grinder armature with your own hands, step by step instructions, video

The angle grinder’s armature is subjected to thermal, mechanical and electromagnetic stresses above all other components. It is therefore a frequent cause of tool malfunctions and as a consequence often needs to be repaired. How to check the armature for functionality and repair the element with your own hands. in our article.

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Angle grinder armature structure

The angle grinder motor armature is a conducting coil with a magnetic circuit, into which the rotating shaft is pressed. It has a pinion at one end and a collector with lamellae at the other. The magnet wire consists of grooves and soft plates coated with varnish to isolate it from each other.

Two conductors of the armature winding are placed in each groove according to a special pattern. Each conductor is half a coil, the ends of which are connected in pairs on the lamellae. The beginning of the first coil and the end of the last coil are in the same groove, so they are shorted to the same lamella.

How to Test an Angle Grinder Armature for Proper Operation

If the armature is defective, the motor will overheat, the winding insulation will melt and the windings will short-circuit. The contacts that connect the armature winding to the collector plates are unsoldered. Current stops flowing and motor stops running.

Standard diagnostics

Before taking the diagnostic tool, examine the armature. There could be damage. If the winding is melted, burning of the insulation varnish will leave black marks or a peculiar smell.

You can see bent and crumpled coils or conductive particles, such as solder residues. These particles are the cause of a short circuit between the coils.

The blades have curved edges called roosters for connection to the winding.

This contact damage causes the lamellas to burn out.

Other damage to the collector: raised, worn or burned plates. Between the blades can accumulate graphite from the brushes, which also indicates a short circuit.

How to check with a multimeter

  • Put a resistance of 200 ohms. Connect the probes of the instrument to two adjacent lamellae. If the resistance is the same between all adjacent plates, the winding is fine. If the resistance is less than 1 ohm and very near zero, there is a short circuit between the coils. If the resistance is two or more times the average, then there is a winding breakage. Sometimes when an open circuit occurs, the resistance is so great that it will go off-scale. On an analog multimeter the arrow goes all the way to the right. And the digital will show nothing.Diagnosing armature windings with a multimeter
  • Ground fault detection is done if there is no open winding. Put the maximum resistance on the meter scale. Depending on the tester it can be from 2 megohms to 200 megohms. Connect one probe to the shaft and the other to each plate in turn. If there are no faults, the resistance should be zero. Do the same with the rotor. Attach one probe to the iron body of the rotor and move the other probe along the lamellae.

How to repair the armature at home

The armature is the cause of one-third of all screwdriver malfunctions. In the case of the daily intensive work, faults can already occur in the first six months, e.g. if the brushes are not replaced in time. A screwdriver will last a year or more if it is used sparingly.

Anchor can be saved if it is not out of balance. If you hear an intermittent hum and a strong vibration during operation, it is an imbalance. Such an armature must be replaced. The winding and the collector can be repaired. Short-circuits can be repaired. If a substantial portion of the winding is damaged, it can be rewound. Rebore, rebuild, or solder worn or badly damaged blades. Also, do not attempt to repair the armature if you are unsure of your abilities. It’s best to replace it or take it to a repair shop.

Flush manifold

Over time there will be brush wear on the collector. To get rid of it, you need to:

Don’t forget to clean any shavings from the rotor so that no shorting occurs.

Use an emery board to remove the impregnation residue without damaging the insulator. Count the conductors in the groove. Calculate the number of turns in the section and measure the wire diameter. Draw a diagram. Cut insulating sleeves from cardboard and insert them into the grooves.

After the armature is wound, weld the section leads to the collector lugs. Now check the winding with a tester and a short-circuit indicator. Start impregnating.

Impregnation instructions (taking into account the speed regulator)

  • When you are sure that there are no problems, put the armature in the electric oven to warm it up for the epoxy to flow better.
  • After warming up, place the armature on the table at an incline for better spreading of the wires. Drop resin on the front end and slowly twist the anchor. Drip until adhesive appears on the opposite forehead.

Air dry the armature until cured

At the end of the process, lightly grind the collector. Balance the armature with a dynamic balancer and an angle grinder. Now turn the final round on the bearing. Clean the slots between the blades and polish the collector. Do a final check for opens and shorts.

The peculiarity of the winding for variable speed grinders is that the rotor is wound with a power reserve. Current density affects RPM. The wire cross section is overstated, and the number of turns is understated.

How to test the armature with a multimeter?

To do this procedure, you will need the meter itself and the tools to disassemble the device. How to wire the armature with a multimeter. instruction:

  • Prepare the work surface. There should be enough space to arrange the necessary tools and parts removed from the device.
  • Disassemble the angle grinder and remove the armature.
  • Clean the part of dirt and dust.
  • Using the directions in the video below you will be able to test the armature yourself with a multimeter.

At the start of the diagnosis, set the meter to 200 kohms. If your multimeter doesn’t have such a scale, you can limit yourself to 20 kOhms. To test the armature, one feeler of the meter is put on the mass, and the other touching each of the plates. If no reading appears on the analog multimeter scale or the digital multimeter screen, there is most likely an inter-turn short in the armature winding. The problem can be accurately diagnosed with a special tool that professional locksmiths have.

Repair: Fixing an insulation breakdown

If the insulation breakdown was small and you found it, you need to clean the area of fouling and check the resistance. If its value is normal, insulate wires with asbestos. Drop a quick-drying glue like “Supermoment” on top. It will soak through the asbestos and insulate the wire well.

If you still can’t find the place of the insulation breakdown, then try carefully impregnating the winding with electrical impregnation varnish. The pierced and un-pierced insulation will soak in this varnish and become stronger. Dry the armature in a gas oven at about 150 degrees. If that doesn’t help, try rewinding or replacing the armature.

Soldering the collector plates

The lamellas are mounted on a plastic base. These can be wiped down to the base. Only the edges are left where the brushes can’t reach.

Such a manifold can be rebuilt by soldering.

  • From a copper tube or plate, cut the necessary number of lamellas to size.
  • After you have stripped the armature of any copper residue, solder with regular tin and solder acid.
  • When all the lamellas are soldered, grind and polish. If you do not have a lathe, use a drill or screwdriver. Insert the armature shaft into the chuck. Grind it first with a file. Then polish with zero-grit sandpaper. Don’t forget to clean the slots between the blades and measure the resistance.
  • There are incompletely damaged lamellae. To rebuild them, it is necessary to make more thorough preparations. Lightly grind the collector to clean the inserts.

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