How to check the armature of the angle grinder at home


Modern electrical equipment is equipped with motors with additional protection devices such as thermal fuses, thermal relays and motor speed sensors.

  • Thermal fuses interrupt the power supply circuit at a certain threshold of the engine heating. Its serviceable condition will be evidenced by a tester reading as a short circuit;
  • Thermal relays replace fuses. Some of them are in operating condition with closed leads, others. on the contrary. with open contacts. This can be easily checked with a tester;
  • Motor revolution sensors are usually installed in washing machines. Three outputs are used for testing. After removing the contact chip, take turns to put the red probe on the outer pins of the sensor, and keep the black probe on the central terminal. When rotating the rotor in one of the options, the multimeter should show dynamic readings.

How to test the armature with a multimeter

In order to test it correctly, it is necessary to know the principle of operation and the construction of the rotor. Its main structural parts are:

  • The core is round, which is a set of plates made of electrical steel;
  • The winding, wound in a certain way in the slots of the core.

check, armature, angle, grinder

Following a special scheme, two winding conductors are placed in each of the slots. Each of the conductors is half a coil. Its ends are connected in pairs on lamellae. The end of the last winding and the beginning of the first are placed in the same groove and are short-circuited.

Before you check the armature with a multimeter, it is necessary to examine it carefully for various damages:

  • melted wiring;
  • of the burnt insulating varnish;
  • Deformation of the turns;
  • The presence of conductive particles (like solder residues), which often cause short circuits;
  • bent edges of the lamellae (cocks) that connect them to the winding, causing the lamellae to burn out;
  • Accumulation of graphite from deteriorating brushes between the lamellae, which also causes short circuits.

Step-by-step instructions

Directly checking the armature with a multimeter is as follows:

  • Insert the appliance probes into the corresponding sockets.
  • Set the resistance measurement mode. Measuring range. 200 ohm.
  • Use the styli to touch each of the two adjacent lamellae one by one, recording the results on the multimeter display. You will have to test each pair of adjacent plates in series.

Decipher the results of

Deciphering the results of the armature test with a multimeter:

  • When the resistance between all pairs of adjacent plates is the same, draw a conclusion about the serviceability of the armature winding.
  • If the resistance is less than 1 ohm or close to zero, then there is a short circuit between the coils.
  • If the resistance is two or more times greater than the average, you need to look for a breakage in the winding turns. When the resistance is very high, the screen of the digital device will not show anything at all, and on the analog device the arrow will go off-scale.

Repair, replacement, rewinding

After conducting diagnostics and determining the types of rotor faults, the decision on repair methods follows. It is possible to make repairs with your own hands, which will be associated with independent rewinding of the armature. If this option seems time-consuming and complicated, you can follow a simplified scheme and replace the burnt rotor with a new one, corresponding to the model of angle grinder. The easiest, but also the most expensive option is to contact a special service.

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When deciding to repair the anchor with their own hands to help information that is available in the links “How to remove the anchor from the angle grinder”, “Replacing and repairing the anchor of angle grinder“, “Rewinding the anchor of angle grinder with their own hands”.

Sections: Grinder repair with their own hands, Grinder Anchors

Previous article: Repair with their own hands the stator of angle grinder Next article: Rewinding the armature of angle grinder with their own hands

Features of malfunctions

If the motor of the power tool began to work badly or completely failed, many send to scrap not only the collector electric motor, but also the entire device. It is not necessary to do this.

The usual check, carried out with their own hands, allows you to check the node, to assess its current state. What is most interesting, in most cases, the device can be returned to working condition, having spent a minimum of effort and money.

test armature multimeter how to check armature Hindi Urdu

  • Before you start checking and repairing carefully, don’t be lazy to look at the condition of the 220V cable. It is not uncommon for a cord check to show that a break has occurred in it. Because of this, the collector motor does not function;
  • Another possible problem is the failure of the buttons that are responsible for controlling and turning on. They can also lose contact, broken mechanically. Checking them will answer this question;
  • It will also not hurt to check the starting and regulating device if it is present;
  • A 220-volt power source. What is the condition of the 220 volt outlet? Do not rule out the situation where the voltage of 220 volts simply does not go to your electric motor and all power tools. It is trivial to advise to make sure that there is light in the house. But it is worth checking the condition of the 220-volt outlet. To do this, connect the unit to another 220 volt source. If all is well, move on to the most common breakdowns of a collector electric motor.

Popular Electric Motor Faults

Next, let’s give some advice on the most common breakdowns that can plague an induction or synchronous collector electric motor. This will allow the next time to safely connect the device to 220 volts and start working with it.

  • Disassemble the power tool, disassemble the electric motor of your household appliance. It is recommended that you refer to the manufacturer’s instructions. Before you start to dismantle the tool into its component parts, make sure there are no sparks. They should not be on the brush contact mechanism.
  • If the sparking is active, the brush-collector assembly is most likely worn out or the contacts are faulty.
  • A less common cause of arcing is a shorted winding in the collector. Specifically, an interturn fault.
  • The most common breakdown is wear of the brush-collector assembly. Either the manifold assembly is black. If the brushes are worn out, they need to be replaced with identical new elements. Ideally replace with genuine parts. Usually the brush-collector assembly is easy to change. To do this, you need to pull back the lock or unscrew the fixing bolt. It all depends on what kind of device you have in front of you.
  • Some models of asynchronous or synchronous motors do not require brushes replacement but a complete brush holding mechanism. Do not forget to connect the copper wire to the contacts.
  • If the brush holder assembly appears to be intact, try stretching the springs that hold them in place.
  • If the contact part of the collector is dull, try simply sanding it down with a emery cloth.
  • If a groove has formed where the collector contacts the brushes, it will be necessary to make a turning on the machine.
  • Another, not less widespread type of breakage in such electric motors is bearing wear. If the inspection shows that there is cartridge runout, increased housing vibration during operation, the bearing will have to be replaced. The most unpleasant scene is when the armature begins to touch the stator. At a minimum you will need to replace the armature, or swap out the stator and armature at the same time.
  • Microcontroller control. If the microcontroller control fails, then the problem may be in the microcontroller itself. It may be easiest to replace with a new one.
  • State of the rotor. The rotor of your motor may also have a problem. Use a multimeter to check the rotor.
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Rare problems

If windings or lamellae are likely to be faulty, a visual inspection may be helpful to determine whether or not there are any breaks. There are a few things to note when making repairs.

Armature Restoration of Angle Grinder

  • Check the condition of the windings. Generally, windings tend to be damaged, which can lead to irregularities.
  • Examine the current color of the windings. All or just part of the windings may be black, indicating a problem.
  • Check the contact conditions on the collector field wires. If there are problems, ordinary re-soldering will constitute your entire repair.
  • Look into the space between the lamellae. This is to check for graphite dust clogging. If it is here, the repair consists of the usual cleaning. The assembly may be cleaned with improvised means.
  • Smell the insulation on the wires. Often the tool cannot be operated, it fails because the wiring insulation node has simply burned out. If this occurs, it emits a characteristic odor that many people are familiar with.
  • If any breaks in the stator or armature windings are found, they need to be replaced. Another option is to rewire the elements, for which it is best to contact a service center.
  • Check the rotor. An evaluation of the rotor using a multimeter will show what action to take next.

If a visual inspection does not determine the fault, you will need to wire the assembly with a multimeter.


Connection to an overloaded mains is one of the causes of breakdowns of angle grinders Before you ring the stator of an angle grinder with a multimeter, you need to familiarize yourself with the precautions when using angle grinders. Among the main recommendations are the following:

  • Do not overload the motor so that it does not overheat during operation;
  • Use replacement discs of suitable diameter;
  • Do not allow large quantities of dirt or debris to enter the housing;
  • The way to cover up any imperfections is to keep the bearings and gearboxes greased;
  • Do not plug the tool into an overloaded power socket as this will impair the tool’s function.

People who frequently use an angle grinder occasionally encounter armature failure. To determine the cause of the malfunction, you need to check the part with a multimeter. Before you do this, however, you should familiarize yourself with how to do it properly.

Factors that cause the stator to fail:

Signs by which you can understand that the stator is faulty:

  • smell of burning insulation appears.
  • The housing overheats.
  • Smoke appears.
  • The shaft rotation slows down or stops.
  • Unintentional loosening of the shaft, the tool rapidly reaches maximum speed.

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

The winding wires are coated with a protective layer of insulating varnish. Overheating can cause the stator to overheat and break down. This causes a short circuit of the windings. The lacquer gives off a peculiar odor. Short-circuiting just one of the wires completely puts the angle grinder out of operation.

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Rules to help avoid overheating the motor of the angle grinder:

  • Do not turn off the unit immediately after working at low speed, but after about one minute.
  • Take frequent breaks when working under load at reduced speed.

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

Checking, repairing and replacing the angle grinder‘s armature with your own hands

If the angle grinder fails, diagnostics is performed to identify the causes. One of these could be a fault in the armature (rotor) of the drive. You can carry out the health/failure test of this rotating assembly yourself. Only simple devices should be available for performing a wire-circuit test.

Short circuit indicator check

A winding breakage or short circuit in the winding can be detected with a short circuit indicator (IC). Other names. the indicator of inter-turn short circuit or indicator of defects of windings of electric machines.

  • power supply unit;
  • case with LCD display, sockets for connecting accessories;
  • of the connecting wires;
  • of a large inductive sensor;
  • Small inductance sensor.

The principle of operation of the indicator is based on the induction of pulse electromotive force in the tested winding. If there are shorted windings, a magnetic field pulse from the short-circuit current flowing through them is recorded.

How to check the stator of angle grinder by IDVI device:

  • Inspect the inter-turn short-circuit indicator. Make sure that no external damage has occurred and that the connection cables and sensors are undamaged.
  • Connect the power supply.
  • Press the power button and check that the machine is operating correctly.
  • 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.
  • Switch off the power supply to the angle grinder.
  • Choose either the small or the big probe according to the stator size.
  • If the angle grinder’s data sheet does not specify the rated voltage per winding turn, it must be determined according to the formula: The rated voltage of the entire coil divided by the number of windings.
  • Switch on the device.
  • Set on the indicator the pulse test voltage amplitude which is larger than that received during the calculation.
  • Pressing the sensor to the surface of the winding, consistently check all the grooves, waiting for 3-4 seconds. If a short circuit is detected, the instrument will beep and the corresponding inscription will appear on the display.
  • If no shorted turns are found, then set the next higher amplitude on the instrument and make sure that the winding has enough insulation strength.
  • Switch off the unit.

With a winding defect indicator you can check the condition of the insulation between the stator and rotor coils, as well as between the stator winding and the angle grinder housing. If you can not buy a ready-made device, you can make a simpler indicator of short-circuited turns by yourself.

Armature repair possible

Angle grinder armature cannot be repaired if vibration is present because the balance is upset. This situation requires replacement. Short-circuit repair and winding replacement possible.

First the motor must be disassembled and the rotor removed. But first disconnect the power terminals and remove the brushes. Angle grinder rotor comes with support bearing and impeller for cooling.

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