How To Check The Anchor Angle Grinder With A Multimeter Video

Inspection of the device from the inside

If everything is in order with the power supply, but the angle grinder does not work, you will have to open the case to gain access to the motor. As a rule, disassembly is NOT difficult. But it is necessary to adhere to simple rules that will avoid troubles during reassembly:

  • Be sure to unplug the appliance before disassembling.
  • Remove the working disc and the protective cover from the spindle.
  • Open the case in a well-lit place, on a clean table surface.
  • Remember the location of all parts and assemblies before disassembly. It is recommended to sketch or photograph the internal structure of the device.
  • Fold the screws and fastening screws in a separate place so as not to get lost.

It is best to inspect the motor under bright lighting so that all small details are clearly visible. The armature should rotate freely around its axis, properly functioning bearings should NOT make a sound during operation. There should be no traces of melted wiring on the armature, the loop windings should be intact, without breaks. You can smell the rotor. In the case of turn-to-turn closure, the insulating varnish burns and emits a persistent specific odor. But for such a diagnosis, certain experience is required.

Disassembly angle grinder

To check the short circuit on the stator and rotor, you need to disassemble the household tool motor. Consider performing this operation to troubleshoot an angle grinder.

  • How To Check The Anchor Angle Grinder With A Multimeter Video

    Remove the protective cover by unscrewing one screw on Foma;

  • We unscrew the 4 screws and disconnect the gearbox with the motor from the handle of the angle grinder;
  • Then, from the side of the gearbox, unscrew the 4 bolts and disconnect the gearbox, together with the motor rotor;
  • The stator remained in the case connected to the power and power button.

Having disassembled and disconnected the parts necessary for checking, we proceed to their external inspection, checking for turn-to-turn closure.

replacing bearings with an angle grinder. Visual inspection from outside

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

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

Checking the angle grinder rotor by various methods

Some people test a broken tool with a tester. A fairly correct solution to the problem, but in this case, this measuring device, unfortunately, has little to show us.

You need to understand that the armature of a small motor of a construction tool has a winding and a magnetic circuit where the rotation shaft is located. One end ends with a pinion gear, the other with a lamella collector. The magnetic circuit has soft plates and grooves, which are covered with a special coating for insulation.

As the internal diagram of the rotor shows, in the grooves of the part there are conductors of the armature winding, there are two of them. Each of them is half a turn, the edges of which are connected in pairs in lamellas. In one groove are placed: the first turn (its beginning) and the last (end), which are closed on one lamella.

So how is an angle grinder anchor checked? Rotor problems can only happen in certain cases and for the following reasons:

  • Breakage of conductors;
  • Turn-to-turn closure;
  • Insulation breakdown. In this case, the winding is closed to the metal base of the armature, in most cases the fault of such a breakdown is a violation of the insulating winding of the conductors;
  • Desoldering the collector output;
  • Unevenly worn manifold.

If the armature is defective, this leads to overheating of the engine, which causes the insulation protection to melt, the result. Short circuit of turns. Further, there is an independent soldering of the contacts, which serve as a connection between the rotor winding and the collector plates. The current stops flowing and the tool motor does NOT function.

The stator of an angle grinder can also be a prerequisite for the failure of a power tool.

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

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

If the angle grinder fails, diagnostics are performed to identify the causes. One of them may be a breakdown of the armature (rotor) of the electric drive. You can check the functionality / failure of this rotating unit yourself. It is necessary to have in the arsenal only simple devices for carrying out the continuity of the electrical circuit.

Visual inspection for malfunction

The very first and easiest way to determine if the stator is faulty is to visually inspect it. For what it is necessary to get it out of the body of the power tool. Disassembly here will NOT present any difficulties. The main thing is to free it from all other structural elements of the angle grinder, including the rotor. This will make it possible, with appropriate good lighting, to inspect all surfaces of the stator winding. Usually, charred areas appear in the cliffs, which allows us to conclude that there is a defect. If a visual inspection failed to identify a malfunction of the stator, you should resort to the help of Special devices.

On this topic

Custom check

The most accurate way is to check the stator with a metal ball and a step-down current transformer. The stator is connected to the terminals of the three phases from the transformer. After checking the correctness of the connection, we turn on our low-voltage circuit into the network.

We throw a ball inside the stator and observe its behavior. If it “stuck” to one of the windings. This means that an inter-turn closure has occurred on it. The ball spins in a circle. The stator is OK. A rather unscientific, but effective method of detecting an interturn short circuit on the stator.

How to check the anchor angle grinder for serviceability

Types of armature malfunctions:

  • Breakdown of insulation to ground. This is the short circuit of the winding to the metal rotor housing. Occurs due to the destruction of insulation.
  • Wiring collector leads.
  • Uneven collector wear.
  • If the armature is faulty, the motor overheats, the winding insulation melts, the turns are short-circuited. The contacts connecting the armature winding with the collector plates are unsoldered. The power supply is cut off and the motor stops running.

    Types of anchor diagnostics:

    • Visually;
    • Multimeter;
    • Light bulb;
    • Special devices.

    How to check the stator of an angle grinder with a multimeter

    The stator as an element of the electric drive of the angle grinder participates in the creation of an electromagnetic field in which the rotor rotates, which creates a torque on the spindle shaft. During operation, for a number of reasons, it fails. Users can diagnose damage and repair the stator by themselves.

    How to check with a multimeter

    • Put a resistance of 200 ohms. Connect the test leads of the instrument to two adjacent lamellas. If the resistance is the same between all adjacent plates, then the winding is intact. If the resistance is less than 1 ohm and very close to zero, there is a short circuit between the turns. If the resistance is two or more times higher than average, then there is a break in the winding turns. Sometimes, when there is a break, the resistance is so great that the device goes off scale. On an analog multimeter, the arrow will go all the way to the right. And on digital it will show nothing.
    • The determination of the breakdown to ground is done in the absence of a winding break. Set the maximum resistance on the scale of the device. Depending on the tester, it can be from 2 MΩ to 200 MΩ. Connect one probe to the shaft, and the other to each plate in turn. In the absence of faults, the resistance should be zero. Do the same with the rotor. Connect one probe to the iron body of the rotor, and move the other along the lamellas.

    Visual inspection

    Even if you have a full arsenal of instruments for checking the electrical circuit of the armature, never 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 operation of the rotor will determine the nature of the faults.

    Charred traces and the presence of a specific odor are a prerequisite for burnt insulation and, ultimately, damage to the winding wires. Pay attention to wrinkled or swollen turns, which can authorize the presence of breaks in this place. Solder particles may be present on the windings, which are source of short circuits.

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


    The presence of a turn-to-turn short circuit in the rotor can be determined using an armature tester. It is a transformer with one primary winding.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.

    Tester, multimeter

    The device is a multimeter or its other name is a tester for measuring electrical parameters: current, voltage, resistance. Can be used to search for wire breaks in windings or breakdown them onto the core body.

    In the following, the author offers a diagnostic option from simple to complex. With the help of a multimeter, the stator is called first. It is much easier to check it than the rotor. If there are no breaks and breakdowns of the winding to the case on the stator, then we can conclude that the armature is faulty. This is followed by its diagnostics in more detail with the definition of the exact type of defect and the determination of the method of elimination. Continuity is carried out with a multimeter in the “resistance test” mode with a set minimum measurement scale (up to 200 Ohm).

    In this, as in the other, the process of determining winding breaks is shown, which is really quite laborious, since measurements are taken between each pair of lamellas along the entire circuit of the collector. At the same time, on an armature winding that does NOT have breaks, all the multimeter readings should NOT differ from each other within 0.1 ohm. It is much easier to check the breakdown of the windings on the body by placing one probe on the core body, and the other on the collector plates. The scale of the multimeter does not have to react in any way with readings.

    It is impossible to determine the turn-to-turn short circuit with a multimeter. Other devices are used here.

    Turn-to-turn closure indicator

    In the following, the author tests a device for determining the turn-to-turn closure (IMZ) of his own manufacture. The principle of its operation is based on the interaction of electromagnetic fields created by the coils of the IMZ device and the armature or stator windings. In the presence of a turn-to-turn short circuit, the parameters of the magnetic field of the device change, which is fixed by a light indication. The red light comes on, if there is no short circuit, the green light is on.

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

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

    If the angle grinder fails, diagnostics are performed to identify the causes. One of them may be a breakdown of the armature (rotor) of the electric drive. You can check the functionality / failure of this rotating unit yourself. It is necessary to have in the arsenal only simple devices for carrying out the continuity of the 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 windings (short-circuit indicator, armature checking device and others).

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

    Read more:  How to Remove Gear from Anchor Angle Grinder