Checking The Anchor Angle Grinder With A Multimeter

Visual inspection of breakage

Any, even the highest quality tool is prone to breakage. Especially if it is heavily exploited. In the event of a breakdown of the angle grinder, you are unlikely to be able to repair the tool yourself. However, a preliminary examination can be carried out without special skills.

Most often, the anchor breaks down in Bulgarians. The breakage can be mechanical. A visual inspection will show uneven wear of the brushes, as well as their burning. In addition, if the anchor is faulty, the angle grinder will vibrate and heat up.

There are electrical breakdowns. These include:

  • Damage to the armature winding;
  • The presence of a short circuit in the turns;
  • Broken resistance between core and winding.

Such malfunctions can be identified using special measuring instruments, for example, a multimeter.

Checking The Anchor Angle Grinder With A Multimeter

Checking the anchor with a multimeter

In order to carry out such a check, you must disassemble the angle grinder and gain access to the anchor. The multimeter must be set in the range of 200 Ohm, and with the probes of the device touch two adjacent lamellas.

We carry out measurements on all turns of the winding, if all the readings are the same, then the anchor is in good order. If on some loop the resistance values ​​differ, then there is a malfunction. You should also check the body of the armature winding.

How to check an anchor on an angle grinder with a multimeter

Even if a man is not a professional craftsman, but simply as a good owner repairs everything in the house himself, he cannot do without a quality tool.

A large selection of grinders, screwdrivers and other tools is available on the website http://m-online.Kiev.Ua/category/158-bolgarki.Aspx.

Solution to the problem

This type of diagnosis is rather complicated. You must have the skills to work with a multimeter, as well as be able to disassemble the angle grinder.

If your tool suddenly stops working, then it is better to immediately go to the workshop:

  • Even if you make sure that it was the anchor that was out of order, and establish the cause of its breakdown, you will hardly be able to replace it or repair it yourself. You still have to carry the tool to the workshop;
  • If the tool is still under warranty, opening the angle grinder by yourself may void the manufacturer’s warranty.

To ensure long tool life, choose products from renowned companies with extensive experience in the industry. Also, follow the rules for operating the tool, because very often they fail for this very reason.

Tips in the article “Open electrical wiring in the interior” here.

Checking the motor armature, how to check the angle grinder:

Checking the armature / rotor and stator with a multimeter / tester

In the following, as a tool for diagnosing the rotor and stator of an electric drive, a multimeter device or, as often in everyday life, called a tester. Applicable for measuring various electrical parameters: resistance, current, voltage. To determine faults in the form of wire breakage, winding breakdown on the case the “ohmmeter” mode is used, that is, a certain resistance value is set, which is comparable to that in the tested circuit. In this case, with a limit of 200 ohms.

Breakdown of the stator to the housing is determined by applying indicator probes to its body and one of the ends of the winding. The presence of any resistance value on the indicator indicates the presence of a defect in the form of a breakdown of the winding onto the case. When diagnosing a winding break, the indicator of the device will not show anything when combining the probes with the winding leads.

complex manipulations should be carried out when checking the rotor windings of the electric drive. A winding break can be in any connection with a single collector lamella. Therefore it is necessary check resistance between all collector lamellas, by applying indicator probes to them in turn. In the absence of a break, the resistance will have the same small value in all cases. Any deviation indicates a break. The breakdown of the winding on the case is checked with probes when they come into contact with the collector and “iron” from a set of sheets of electrical steel. The indicator scale should not react to this action.

However, it is impossible to determine the turn-to-turn circuit with a multimeter. Here, a device called a short-circuited loop indicator (IKZ) is used. details about it in the information below.

How to ring the stator angle grinder

408-317 Stator for BOSCH GWS7-125 / GWS7-115 HAMMER. Photo 220V

The stator as an element of the electric drive angle grinder participates in the creation of an electromagnetic field, in which the rotor rotates, creating a torque on the spindle shaft. During operation for a number of reasons it fails. Execute damage diagnosis and stator repair user can independently.

  • Device
  • Causes of malfunction and characteristic symptoms
  • Visual inspection for malfunction
  • How to check the stator winding of an angle grinder at home in different ways
  • Checking the armature / rotor and stator with a multimeter / tester
  • On turn-to-turn circuit, indicator
  • Makita, without instruments
  • Multimeter. Automatic: quickly and efficiently performs measurements

On turn-to-turn circuit, indicator

The principle of operation of the device for determining the turn-to-turn closure is shown in the following. Device in the tested winding induces a magnetic field. If there are short-circuited turns in the winding, the short-circuit current causes an increased resistance to the electromagnetic field generated by the device. By adjusting the IKZ, a setting is performed, upon reaching which light signal is triggered (the indicator light changes from green to red) or soundtrack is heard. In addition to the main application, the author shows a way to determine the places of connection of the winding wires to the collector lamellas, in the absence of visually visible contacts.

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The stator of the angle grinder is fixed core structure, made of sheet electrical steel. It has grooves in which winding, twisted in a certain way, its wires are located parallel to each other, to reduce eddy currents.

408-316 Stator for BOSCH GWS6-100 / GWS6-115 HAMMER. Photo 220V

Mandatory winding covered with insulating varnish in order to protect against a possible short circuit of the wires among themselves. In the grooves of the cores between the coils insulation made of electrical cardboard, glass tape and other similar materials. In the vast majority of grinder models the stator is tightly fitted inside the housing made of high-strength plastic, which protects the entire electrical part of the angle grinder.

Causes of malfunction and characteristic symptoms

The main factors that affect the stator output out of order are as follows:

  • The supply network does not always guarantee a stable voltage, its surges are possible;
  • During the operation of the power tool, any liquid, such as water, may enter the stator;
  • When processing some materials (concrete, wood and others), a sick amount of dust is formed, from which it is difficult to protect itself from falling on the stator winding;
  • Long-term operation of the angle grinder under overload conditions, which causes the power tool to overheat;
  • During operation, do not stop the angle grinder by pulling the cord out of the socket suddenly.

408-105 Stator for Hitachi G18SE3 and HAMMER angle grinders. Photo 220V

Typical signs of a stator malfunction are as follows:

  • A persistent smell of burnt insulation of the winding wires appears;
  • The temperature of the body parts rises significantly Angle grinder;
  • The electric drive of the angle grinder hums more than under normal conditions;
  • The appearance of smoke is quite real;
  • The spindle starts to rotate more slowly, or even may stop completely;
  • The opposite to the previous case is possible, the other extreme. The spindle starts to spontaneously work at increased speeds, it is peddling.

Makita, without instruments

In one of the Makita models in the next while working smoke went, which is correct a sign of a burnt rotor or stator. To determine the reasons, the author performed a complete disassembly of the angle grinder, making it possible to perform a good external examination of the units suspected of malfunctioning the angle grinder. If there were no signs of smoke consequences on the rotor, then on the stator several places of burnt electrical insulating varnish clearly visible.

Checking contacts with a light bulb

If there is no tester, you can get out of the situation with a simple 12 volt light bulb. The power can be any, optimally 30-40 watts. The voltage from the 12 volt battery must be applied to the plug of the angle grinder by inserting a light bulb into the break of one wire. With a working anchor, if you rotate the spindle by hand, the light should be on without changing the brightness. If the glow changes, this is a sure sign of an inter-turn short circuit.

If the light is off, then this may indicate the following:

  1. The brushes may hang in the inoperative position. The retaining spring has worked.
  2. There was a break in the supply circuit.
  3. There was a short circuit or break in the stator winding.

There are other diagnostic methods, but they require more sophisticated equipment that is usually not used at home. An experienced foreman will identify a breakdown with a high degree of accuracy using a “punch” or a simple transformer with a split toroidal core and one primary winding.

Continuity tester

If visual inspection does not give clear results, it is recommended to continue the examination with a multimeter. Having set the mode switch to the ohmmeter position (range 200 Ohm), it is necessary to “ring” two adjacent armature lamellas with two probes. If the resistance on all turns is the same, this means that the windings are in good order. If on some pairs the tester shows a different resistance or an open circuit. There is a malfunction in this coil.

Broken wires can occur between the winding and the core. You should carefully examine the junction of the coils with the collector lamellas in the lower part of the armature, visually check the soldering of the contacts.

How to identify a malfunction of an angle grinder armature

Signs of a broken angle grinder armature are: increased sparking of the brushes on the motor manifold, vibration of the motor at low speeds, rotation of the working shaft in different directions. If these symptoms are present, stop using the tool. This is dangerous. Suspicions are easy to check with simple tests.

Visual inspection from outside

Troubleshooting should start with a visual inspection of the angle grinder:

  1. Carry out a general inspection of the tool.
  2. Pay attention to the integrity of the power cord, the presence of voltage in the outlet.
  3. Using the voltage indicator, check that the current flows to the motor manifold and the start button.

: replacing bearings with an angle grinder. How to remove the anchor

Replacing the armature begins with disassembling the angle grinder. The following steps are taken:

    With a screwdriver, the brush units are unscrewed from both sides. The brushes are removed.

Features of checking the anchor angle grinder with a tester

A diagnostic procedure will help pinpoint the problem of a motor part. The device, which is available in the arsenal of tools of many amateur electricians, will allow you to check the anchor of the angle grinder with a tester. With the help of a tester, you can check not only the anchors of the grinders, but also the stator windings of other electric motors. In the picture below, you can see one of these homemade measuring instruments in action.

The indicator lights up when the tester is plugged in. A red light without attaching a technical device to the anchor means the device is ready to be checked. The working active surface of the measuring device has two points of contact with the investigated one. One of them is the generator coil, the second is the coil of communication curls. When checking the armature of an angle grinder with a tester, it is necessary to substitute this surface to the groove under investigation. Make sure that the sensors do not extend beyond the armature plates at the same time on both sides.

If the electrical part is in good working order or has been rewound, then during its check with a tester opposite each of the grooves, the indicator will glow green. If there is a malfunction in the armature of the angle grinder, in particular, a turn-to-turn circuit, a red light will be indicated on the indicator of the device in the place of its localization. Be careful during the diagnostic procedure to ensure proper surface contact when checking the angle grinder armature with a tester. Mechanical damage should not be excluded from the reasons for the failure of the angle grinder, which can be noticed visually without ringing with a multimeter. They can be both significant and small. You may notice a breakdown on inspection by taking apart the angle grinder. It is necessary to diagnose such malfunctions before checking the armature for interturn short circuit.

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If you do not have experience in disassembling a power tool or preparing to work with measuring instruments for ringing an armature with a multimeter and are not confident in your own strengths, you should not interfere with the design of the angle grinder. Do not experiment to avoid damaging the angle grinder. In this case, in order to find the cause of the breakdown of the power tool and check the armature of the angle grinder with a tester, it is better to contact a service center or qualified locksmiths who specialize in repairing equipment.

Checking the anchor with a tester. Expert recommendations. Checking the angle grinder armature with a tester. Possible diagnostic results

Among the most common causes of equipment failure, the most common inter-turn closure of the armature of an angle grinder. It can be detected. Called. With a tester. A multimeter is an electrical measuring device that includes the functions of an ammeter, voltmeter and ohmmeter. They can not only check the presence of a turn-to-turn circuit in the winding of the angle grinder, but also measure the resistance between the lamellas. A simpler device is a tester. By checking the armature of the angle grinder with it, you can detect faults caused by a short circuit.

How to ring an anchor with a multimeter?

To complete this procedure, you will need the measuring instrument itself and tools to disassemble the device. How to ring an anchor with a multimeter. Instructions:

  1. Prepare your work surface. There should be enough space to place the necessary tools and parts removed from the device.
  2. Disassemble the angle grinder and remove the anchor.
  3. Clean the part from dirt and dust.
  4. Using the recommendations in the presented, you can independently ring the anchor with a multimeter.

At the initial stage of diagnostics, the value of the measuring device is set at 200 kOhm. If your multimeter does not have such a scale, then you can limit yourself to 20 kΩ. To ring the armature, one probe of the measuring device is applied to the ground, and the second is touched to each of the plates. If no indicators appear on the scale of an analog multimeter or a digital screen, most likely there is an interturn short circuit in the armature winding. You can accurately diagnose the problem using a special device that is available from professional locksmiths.

What problems in the operation of the device can be detected when checking the anchor of an angle grinder with a tester

If you have sufficient knowledge to carry out the correct disassembly of the power tool, then in some cases you will be able to diagnose the cause of the device breakdown with your own hands. Checking the angle grinder armature with a tester for turn-to-turn circuit will allow you to determine further actions regarding the detection of malfunctions or repair of equipment. If the part is intact and the tool still does not work, seek qualified assistance. Did you check the angle grinder armature with a tester to accurately detect the cause of the equipment failure? If you have the necessary tools, you can repair equipment yourself in such cases:

  • You can try to solder the damaged winding in the upper visible layers. Such an anchor will last some more time. After sealing, it must be checked or ringed with a multimeter;
  • In case of turn-to-turn closure, winding rewinding or armature replacement is required.

Breakdown diagnostics and repairs of the angle grinder can be performed under voltage. For the sake of your own safety, entrust this work to professionals.

Checking, dialing the anchor do-it-yourself angle grinder

Rotor for INTERSKOL angle grinder-2300M, HAMMER. Photo 220V

If the angle grinder fails, diagnostics to identify the causes. One of them might be breakage of the armature (rotor) electric drive. Carry out a functional / malfunction check on this rotating assembly you can yourself. You only need to have in your arsenal simple devices for dialing electrical circuit.

  • Device
  • Causes of malfunctions
  • How to check the serviceability, ring the rotor of the angle grinder at home,
  • Visual inspection
  • Tester, multimeter
  • Turn-to-turn closure indicator
  • Light bulb
  • Throttle
  • Repair, replacement, rewinding
  • How to check the serviceability, ring the rotor of the angle grinder at home,

    In a domestic environment, there are the following methods for diagnosing an anchor:

    • Visual inspection;
    • Using a multimeter;
    • A light bulb and two wires connected to it;
    • Devices specially designed for checking the integrity of the windings (short-circuit indicator, armature checking device and others).

    details about the types of diagnostics in the following information, where there is.


    For competent diagnosis of anchor malfunctions it is important to know the device and how it works. The main elements of the anchor are round core, consisting of a set of electrical steel plates and a winding wound in its grooves in a certain way. In each of the grooves, according to a special scheme, fit two anchor windings. The first and last turn of one of the windings are in the same groove and are closed on one lamella.

    Rotor for Makita angle grinder 9069 MAX. Photo 220V

    Core pressed onto the rotor, rotating under the action of forces arising in the electromagnetic field formed by the armature windings and the stator coils working with it in pair. In angle grinders, an anchor is an assembly with a drive gear located at one end of the shaft and a collector assembly at the opposite end.

    Visual inspection

    Even with a full arsenal of instruments for testing the electrical circuit of the armature, never do not neglect visual inspection. A mandatory first step in the entire diagnostic process. A careful glance will find signs by which a user who knows the design and principles of the rotor will determine the nature of the faults.

    Charred traces and the presence of a specific odor are the cause of burnt insulation and ultimately damage to the winding wires. Attention should be paid on crumpled or swollen turns, which can authorize the presence of breaks in this place. The windings may contain solder particles, which are the source of the short circuit.

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    Violations of the contacts of the windings with the collector can be detected on burned-out lamellas. Damage to the collector itself is visually diagnosed. Raised, worn or burnt plates.

    Causes of malfunctions

    Rotor breakage can be caused by improper operation power tool that represented by the following factors:

    • The permissible time of continuous operation has been exceeded, which is one of the main reasons for the failure of household grinders;
    • Work in corrosive environments with sand, moisture, abrasive dust and other similar materials;
    • Work in conditions exceeding the permissible load;
    • Some mechanical faults affect the imbalance of the rotating rotor, which ultimately affects the normal functioning of the rotor electrical circuit;
    • Instability of the mains voltage when using a power tool.

    Serviceable rotor for Bosch angle grinder GWS6-100 / GWS 850 MAX. Photo 220V

    Operation of a power tool associated with these factors will result in to the following malfunctions:

    • Breakage of the coil conductors;
    • Short circuit between turns due to burnt insulation;
    • The insulation loses its properties, which can cause a breakdown of the winding to the core body;
    • Violation of collector contacts;
    • Particles of burnt insulating varnish or melted solder caught in the gaps that come into contact with the rotating rotor can cause mechanical damage to the elements of the angle grinder: cracks, chipping, deep scratches.
    • Collector lamellas wear unevenly, carbon deposits form on them from a short circuit.

    This mostly happens during long-term work commutator motor angle grinder without rest break. The insulation of the winding from heating loses its characteristics, melts, which leads to a short circuit of the turns. The contacts connecting the armature winding with the collector lamellas can be unsoldered, the electric current is interrupted and the electric drive stops.


    The presence of a turn-to-turn short circuit in the rotor can be determined using an armature tester. It represents single primary transformer, in fact, it is a wire wound on a ferromagnetic core. In this case, a triangle cutout is made in it, in which the tested rotor can be stably positioned. Its winding begins to work as a secondary coil of a transformer.

    In the presence of turn-to-turn closure, the parameters of the rotor magnetic field have a higher intensity, the metal strip placed on the core surface will vibrate and magnetized will be attracted to the core body. The plate will move freely on the rotor core housing if it has normal windings without defects.

    Soldering collector plates

    The lamellas are installed on a plastic base. They can be erased to the very bottom. Only the edges remain, to which the brushes cannot reach.

    Such a collector can be restored by soldering.

    • Cut the required number of slats from a copper pipe or plate to size.
    • After you have stripped the anchor from copper residues, solder with ordinary tin with soldering acid.
    • When all lamellas are soldered, sand and polish. If you don’t have a lathe, use a drill or screwdriver. Insert the armature shaft into the chuck. First file with a file. Then polish with zero sandpaper. Remember to clean the grooves between the lamellas and measure the resistance.
    • There are lamellas that are not completely damaged. To restore them, you need to conduct more thorough preparation. Slick through the manifold to clean the plates.

    Damaged manifold plate

    Expanding the place with a drill

    Lamella blank in the groove

    If the collector was completely worn out, then after soldering it will last no more than a month of active use. And not completely damaged plates after such a repair withstand several brush replacements and are not soldered.

    : Replacing the anchor

    Repairing an angle grinder armature takes a long time. But you have a choice. You can simply change it to a new one or give it to the masters.

    : how is the check going

    If you don’t have a tester, use a 12 volt light bulb up to 40 watts.

    Anchor device angle grinder

    The motor armature of the angle grinder is a conductive winding and a magnetic circuit into which the rotation shaft is pressed. It has a drive gear at one end and a manifold with lamellas at the other. The magnetic circuit consists of grooves and soft plates coated with varnish for isolation from each other.

    Angle grinder anchor diagram

    In the grooves, according to a special scheme, two conductors of the armature winding are laid. Each conductor is half a turn, the ends of which are connected in pairs on lamellas. The beginning of the first turn and the end of the last are in the same groove, so they are closed on one lamella.

    In what cases can you save the anchor and restore it yourself?

    If the damage to the armature is established with guaranteed accuracy, the part must be removed from the electric motor. The motor must be disassembled with special care, after removing the brushes and disconnecting the power terminals.
    The rotor is removed together with the support bearings and the motor cooling impeller, they form a single whole with it.

    If most of the wiring in the armature is damaged and the balance is disturbed as a result of overheating, it is better to replace it entirely. An increase in vibration and an uneven hum during the operation of the mechanism indicate a balance violation.

    How to repair an anchor at home

    Because of the anchor, a third of the breakdowns of the screwdriver occurs. With daily intensive operation, malfunctions can occur already in the first six months, for example, if the brushes are not replaced on time. With sparing use, the screwdriver will last a year or more.

    The anchor can be salvaged if the balance is not disturbed. If during the operation of the device an intermittent hum is heard and there is a strong vibration, then this is a violation of balance. This anchor must be replaced. And you can repair the winding and the collector. Small short circuits are eliminated. If a significant part of the winding is damaged, it can be rewound. Grind worn out and heavily damaged lamellas, build up or solder. In addition, you should not undertake an anchor repair if you are unsure of your capabilities. Better to replace it or take it to the workshop.