DIY repair of angle grinders

In detail: do-it-yourself repair of angle grinders from a real master for the site my.housecope.com.

Have you noticed that the tool always breaks the minute you need it most? And what to do? There is no time to run to the repairmen, and maybe not even run. Maybe try to repair it yourself? It was not the gods who did it. Let's take a grinder for a sample.

Any, even a very complex mechanism, consists of large and small parts. The Bulgarian is no exception. Its main nodes and details:

Frame;
Stator;
Rotor;
Reducer;
Connecting wire;
Switch.

The assemblies can be divided into electrical and mechanical. Electric - stator, rotor, connecting wire. Mechanical - housing and gearbox. Of course, there is also a button, a fork, brushes.

Vala;
Windings;
Contact collector;
Brush holder and brushes;
Ball bearings.

For repairs, you will need a minimum amount of tools - an ordinary screwdriver with a special crown, pliers, a multimeter, electrical tape, thick grease for gearboxes. If we have all this, then you can start repairing yourself.

To simplify the task, troubleshooting and repairs must be performed systematically. There is no need to rush to disassemble the instrument. First, let's define the type of malfunction. The main problem is that the grinder does not turn on. What you need to check:

Serviceability of the power outlet;
Serviceability of the connecting plug;
The integrity of the connecting wire.

If these elements are in good order, then we inspect the contact brushes. Brushes are used to transfer the supply voltage to the contacts of the electric motor collector. The armature windings are soldered to these contacts. If one of the brushes does not contact or is broken off altogether, then the electric current will not flow to the winding and the grinder will not want to work.

Video (click to play).

In order to inspect the condition of the brushes, you must:

Find two coaxial threaded plugs on the body;
Unscrew them carefully;
Remove the brushes.

The brushes are spring loaded, so you should try not to lose the springs. The removed brushes must be the same size. There will be some wear on them, but there should be no chips or transverse cracks that could break contact.

If the brushes are in good condition, you will have to inspect the engine armature. This node is only called an anchor, but in fact it has absolutely nothing to do with an anchor. This is the central shaft of the engine, on which the winding and the collector crown are located. Sometimes, due to heavy loads, a strong spark occurs between the brushes and the collector contacts. As a result, the copper contacts are covered with a layer of oxides and the current does not pass to the winding.

What needs to be done to put the anchor in order? We need to take the usual white rubber band, which is used by draftsmen and art lovers. Use the corner of the elastic to rub the contacts. The oxide film should be cleaned and shine with a copper sheen.

If this operation did not give results, then it is necessary to open the grinder's case and inspect the condition of the internal wires, the phase-shifting capacitor and the winding. The winding should have an even color of the varnish with which the winding wire is covered. Darkening or blackening of the wire or its sections indicates a short circuit in the winding. It is difficult to fix this malfunction with your own hands; you will need to replace the anchor.

The task of the gearbox is to transfer the rotation of the electric motor shaft to the grinder's disk. Moreover, since we have an angle grinder, we also have an angle gearbox. To inspect it, you must:

Remove the disc, if installed;

Remove the protective cover;

Unscrew the four screws on the gearbox housing.

After that, the gearbox must come out of the housing. There are few faults here:

Breakage or significant wear of the gear teeth;
Shaft breakage;
Lack of fixation of gears on shafts.

Defective gearbox elements must be replaced. Replacing a gear is not difficult. The gearbox is then lubricated with a good layer of grease and reinstalled.

The stator is the part of the electric motor that is rigidly fixed in the housing. It is designed to create an electromagnetic field in which the armature rotates. Image - DIY repair of angle grinders

The main malfunction of the stator is a break in the winding or its strong overheating. Why is overheating dangerous? When the winding wires overheat, the protective insulating varnish that covers them also overheats. Violation of the varnish insulation leads to a short circuit of the winding turns.

Even the closure of one turn of the winding completely disables the grinder. The winding immediately begins to overheat and smoke. The shaft rotates slowly or stops rotating altogether.

To repair the stator, you will have to change the windings to new ones or rewind. But rewinding the stator is not a procedure for beginners.

Any instrument must be treated with care. The design of a modern instrument asks for respect by its very appearance. The plastic case, although it has a margin of safety, is shock-resistant. Try to use special soft stands for any instrument. Image - DIY repair of angle grinders

The housing has ventilation holes through which the motor is cooled. During operation, especially when cutting strobes, a lot of construction dust gets into the body. Therefore, after performing dusty work, it is necessary to blow out the inside of the grinder with compressed air. The outer surface of the tool must be wiped with a rag and dirt removed.

After completing the work, you need to remove the disc. This relieves stress on the drive assembly, and at the same time you can inspect and assess the condition.

Do not use a disc with a diameter that exceeds the size established for this grinder. A large diameter disc can be compared to a large lever, with which you try to destroy the mechanism of a tool or burn its electrical windings. In addition, it is not possible to install a protective cover.

After work, the electrical wire must also be wiped clean, remove dirt, and especially oil. The wire must be carefully wound onto a reel or at least onto the grinder's body.

Many power tool users have the bad habit of pulling the plug out of the socket by the connecting lead. Because of this habit, the wire breaks, the socket gets loose. This applies more to people who are sloppy and lazy by nature.

Avoid the possibility of water getting inside the grinder. When working in an open area, have a plastic bag or piece of polyethylene handy to cover the tool at all times to protect it from rain or snow.

In order for the grinder to serve for a long time and reliably, it is necessary to periodically open the gearbox, clean it and apply new grease.

Attention to a tool always has a beneficial effect on its long-term performance and your safety. And this should not depend on the brand of the grinder - it is Makita, sparka or our domestic sample. Image - DIY repair of angle grinders

Do-it-yourself grinder repair is a completely solvable task. The main thing is not to rush, to understand the structure, to remember all the circumstances under which it broke down, to determine what could have worn out during operation, to make diagnostics and start repairing it.

Angle grinder (angle grinder) is called a grinder. The name of the instrument is due to the fact that it was produced by the Eltos-Bolgarka plant in Plovdiv. It is designed to perform work on grinding or trimming hard material:

Performs well sharpening of the tool.

Nowadays, a grinder is a very necessary tool, so almost everyone has it.

There are grinding machines of different power: from 500 W to 2500, depending on the thickness of the wheel - from 115 mm to 230 mm. The most popular in the work are angle grinders with a power of 1.2 W, and the most used disc is 125 mm thick.

Every year the choice for this construction power tool is becoming wider, but the operating rules hardly change. And even if you always adhere to them, sooner or later there are malfunctions in the mechanism that you can try to fix with your own hands, collecting everything you need to repair the grinder.

Any grinder consists of the following parts:

rotor - a part of an electric motor that rotates during operation and is speed-controlled, also called an anchor;
collector - the place on the rotor where the control winding wires are located;
brushes - parts that serve as conductors of current from the cable to the collector winding;
reducer - a mechanism that acts as a drive from a rotating rotor to a rotating disk, consists of a spindle, a bearing, two gears (large and a shaft gear);
stator - the part of the electric motor in which the rotor works;
grinder cooling impeller;
start button;
network cable with electric drive;
protection casing;
grinder body;
additional handle.

All these details can be divided into two parts:

How to disassemble a grinder? Not so difficult process. This does not require special knowledge, but everything must be done carefully and carefully. Each owner needs to know how to disassemble any working tool, because from time to time it needs to be cleaned internally from dirt and trapped dust, and its durability depends on it.

At the present time on the market, you can choose for yourself a different type of grinder, which differ in performance, size, quality. Manufacturers are also different. Whichever model of grinder you buy, everyone has the same assembly model.

Dismantling the grinder will require few tools, you just need a regular screwdriver or a reversible screwdriver with a ratchet mechanism.

Having prepared a screwdriver, you can start disassembling:

We unscrew the screws from the body and remove one side of the product.
Remove the nut that holds the disc, unscrew the bolts securing the protective casing.
We remove the brushes.
Disconnect the wires from the engine.
We unscrew the bolts that secure the gearbox inside, and very carefully remove it, and the rotor is also removed with it.
We unscrew the bolts that hold the stator and remove it.
We put the grinder back, put everything in place in the reverse order and fasten it.

When disassembling the grinder, it is important to remember the order in which the parts are removed in order to assemble them correctly.

In the event of a malfunction, first of all, it is necessary to exclude elementary breakdowns:

The grinder does not turn on. The angle grinder suddenly became faulty - it stopped turning on. In this case, you need to check the serviceability of the outlet, then the plug and the power cord, perhaps the drive simply does not work due to the fact that no current flows into the product.

The cable and plug are intact, but the drive does not work. You need to check the start button. It is easier to repair the grinder switch by purchasing a new button and replacing it. Since it rarely needs to be repaired - basically, the plastic rod of the switch breaks inside. If you want to experiment, you can disassemble it by numbering the contacts, and put everything back together in place so that after assembly does not happen a short circuit.

The above parts are intact and the angle grinder doesn't want to work - so it's time to check the brushes. Perhaps it's time to change them in the grinder. The brushes are constantly heated from work, so they wear out quickly and more often than other parts need to be replaced, and in pairs.

Having excluded all minor breakdowns, it is necessary to understand why the tool does not want to turn on, and how to repair it.Most likely, the malfunctions are serious and require additional knowledge. This happens if:

the body is deformed;

one of the bearings is seized;

the armature or stator does not work;

the teeth of the gear wheel of the reducer are broken or worn out;

the collector is out of order;

the sensor of the control electronics does not show signs of life.

If it is determined that a malfunction has occurred in the mechanical part of the grinder, then you need to pay attention to the condition of the large gear located on the shaft and to the bushings. If the teeth are partially worn out or the shafts are wobbling, they must be replaced immediately.

The most common breakdowns

Grinder malfunctions happen quite often. Everyone who works with this tool knows about this. What goes wrong most often?

Just one awkward pressing of the spindle lock button while the disc is rotating will break it. It can sometimes be broken if used to remove a jammed disc. To prevent this from happening, you need to use an open-end wrench inserted into the special holes near the place where the disc is attached.

It mainly occurs when a jam occurs. If a rumble is heard in the gearbox, this is a symptom of just such a malfunction. When more than one tooth is broken at the gear, the grinder will not be able to cut the required material.

In order for the tool to continue working, it is necessary to change the gears, and everything, and even the bevel wheel. Before going to the store for spare parts, remember the manufacturer's firm, the model and the power of the product.

This type of breakdown happens with angle grinders, which work in places where there is a lot of dust, and when they are given rest, they are left on the ground. Dust that gets inside will damage the winding. Large loads, especially for a small power grinder, turn into a motor breakdown.

If the grinder is used for cutting materials that create a lot of dust, then it is recommended to cover the ventilation holes with something.

The weakest link, and not only among the grinders, are the bearings. A high speed will quickly wear out the mechanism. The good news is that changing the bearing is easy. Replacing a sprinkled bearing at a grinder must be done in time so that a breakdown does not happen that cannot be fixed.

This breakdown is easy to determine when the angle grinder has turned on, but the disc revolutions are too intense and differ from normal operation, which means that there is a turn circuit in the stator on the winding. Stator breakdown is considered the most serious, and special skills are required to eliminate it. When you have doubts about yourself, it is better to turn to professionals so that you do not have to buy a new instrument later.

If the decision to fix it yourself is made, it begins with cutting off the frontal parts of the winding, all the remnants are removed. The next step is to make a new winding according to the template. It must be identical in the number of turns, with the same density, and made of wire of the same thickness as the previous one.

LBM, the power of which is less than 1100 W, are usually equipped with spur gears. They are located on the stator. Bulgarians with more power have helical gears. Each of the options has a conical shape, the rod of the grinder's gearbox crosses with the stator shaft at an angle.

Repair of the grinder gearbox mainly consists of replacing the gears. If the disc gear breaks, it is difficult to replace it because it is very firmly fixed. It is easy to disassemble the gearbox:

you need to unscrew the nut from its side;
gently take the rotor body in a vice and knock out the gearbox housing with light blows;
change the position of the clamped rotor and knock out the bearing through a wooden board;
unscrew the gear from the shaft.

The speed regulator is not present on all models of grinders. When the angle grinder is used for cutting, it is, in principle, not needed, but if grinding is carried out, it is simply necessary.If suddenly it stopped working, then, most likely, the board burned out, which must be removed and bought the same in a power tool store for further replacement.

Self-repair of the grinder is not always feasible. If suddenly something does not work out or everything is not clear, it is better to contact the service center.

Before it completely breaks down, the angle grinder signals the beginning of a malfunction.

Pay attention to the work of your assistant: you should be alerted if:

the brushes began to spark too much;
the grinder is heated during work;
the motor hums inside the case when the tool is turned on;
the vibration of the body has become much greater during work;
the grinder's gearbox is bursting inside;
you hear the sound of a creak of bearings during spin-up or periodic wedging when the rotor shaft rotates;
The angle grinder has smoked, or an uncharacteristic burning smell emanates from it.

In order not to buy a new grinder, you need to be careful about the operation of the tool. In case of any deviations from the usual work, start troubleshooting, determine the cause and repair the power tool.

The service life of the grinder directly depends on the owner's care for it. Each instrument needs good care, then it will work properly for a long time.

Any grinder will warm up during operation, but in order to postpone the repair of angle grinders for a long time, you must adhere to some rules in the work:

Do not overload the tool to avoid overheating and smoke.
Do not put pressure on it while working.
Timely clean and lubricate the necessary parts inside the case.
If malfunctions are noticeable, discontinue operation and inspect for malfunctions.
Replace wearing parts in a timely manner.
If the grinder smokes, immediately stop working and do not turn it on again.
Do not use the tool when processing wood-type material.
Hold the grinder firmly during work so as not to drop or damage.

Adhering to the listed simple recommendations and rules in working with a tool called a grinder, you can extend its life longer than provided for by the warranty period.

Angle grinders during the Soviet era were made in Bulgaria. Therefore, the angle grinder began to be called a grinder. Currently, there are many companies for the production of angle grinders of various models. But the basic elements are the same. Having familiarized yourself with the device, probable breakdowns and diagnostics of the tool, you can repair the grinder of any modification with your own hands.

The grinder is designed for grinding and cutting various materials.

The main elements of the grinder

The grinder consists of the following elements:

The flat aluminum alloy gear housing provides better heat dissipation.
Carbon brushes.
Fastening the handle.
Electronic soft start system. Prevents start-up jerk and reduces starting loads on the motor.
Quick-detachable protective cover.
Ball bearings.
Electric motor.
Grinder switch.

A large selection of bearing products is offered by the Termopolis company -

Main breakdowns and reasons:

For troubleshooting, the grinder must be disassembled.

Remove the nut that holds the scraper disc.

Unscrew the bolts securing the protective cover.

Unscrew the bolts of the grinder body and those with which the body is attached to the gearbox.

Remove the upper part of the back case. Unscrew the bolts securing the cord. Remove the wires and the button from their grooves. In some models, for example, in DWT, the rear case is not disassembled into parts, but removed entirely.

Disconnect the motor wires.

Remove the brushes.

Disconnect the gear case from the grinder body. Together with it, the engine anchor is removed.

Unscrew the gearbox bolts located around the casing mount.

To disconnect the armature from the aluminum housing, unscrew the nut located in the gearbox housing.

Assemble the tool in reverse order.

During operation, the disc can be tightened so tightly with the nut that it begins to crumble. It is impossible to unscrew the nut with a wrench. And you don't need to do this, since you can break the grinder. First, break the disc down to the nut. Then find a metal plate slightly thinner than the scratch disk. With its help, grind off the remnants of the disc under the nut. It can be easily unscrewed with a key or by hand. To avoid bringing the tool to this problem, place a washer under the nut.

For some grinders, for example, Bosh, the casing is not bolted, but snapped into place. To remove it, you need to turn the cutout of the casing perpendicular to the grinder. To dress, turn until it clicks.The stator is checked with a multimeter.

Turn-to-turn closure. Set the resistance mode to 200 ohms. Connect the test leads of the device to the ends of one winding. One means open, and zero means short circuit between turns. If it shows a resistance of more than 1.5 ohms, then check the second winding. Both windings should have approximately the same resistance.

Breakdown to ground or short circuit of the winding with the metal stator housing. Set the multimeter to the maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal stator housing. The unit indicates the absence of breakdown.

First, visually inspect the manifold and winding. There may be visible damage: black marks, bent windings, raised, worn or burnt collector plates. After inspection, proceed with the tester check. Put a resistance of 200 ohms. Connect the test leads to the two adjacent manifold plates. If the resistance is the same between all adjacent plates, then the winding is in good order. 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. 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 plates.Put the tester in the dialing mode.Insert one probe into the outlet of the button and the other into the opposite inlet.Click the button. A sound signal indicates the health of this part of the button.Do the same with the other input and output buttons.

Try not to use the grinder outdoors in winter. The engine heats up while you are running. The air is icy. As a result, condensation forms. Moisture is harmful to the engine.

Always use the discs recommended by the tool manufacturer. If the grinder is 180 mm, do not put more than 200 mm there. The larger the circle, the lower the rpm should be. You will have to remove the protection, and the turnover will be exceeded. Oscillation and vibration will increase. As a result, the circle will fly apart. This is fraught with not only serious injuries. The bearing of the reducer is broken, the gears are erased.

If you actively use a grinder, then you are a good craftsman. It will not be difficult for you to understand the structure of the tool and fix it with your own hands. First, find the problem and determine which parts to check.Repair the grinder carefully, without haste, so that a minor breakdown does not turn into a major one.

The grinder, being the most demanded tool in the house, is subject to considerable stress and intensive use. Because of this, after some time, it happens that when the engine is started, jerks, a burning smell and other malfunctions appear, suggesting that the angle grinder (angle grinder) has broken down. But do not immediately carry the device for repair or buy a new one. Most faults in this device can be rectified by yourself.

Over the long years of the existence of such a tool as angle grinder, its appearance, as well as its internal structure, have practically not changed. To repair a grinder with your own hands, you need to know the structure of its mechanical part, as well as electrical.

If you look at the figure below, you can see what parts the angle grinder consists of.

Wheel for adjusting the spindle speed of the unit.
An electric motor consisting of a rotor and a stator.
Start button. Sometimes a soft start system is connected to it.
High impact plastic housing.
Spindle lock button (used when changing tools).
Safety clutch. Protects the motor from overload when the tool is jammed.
Protective cover. Covers the tool and protects the user from escaping particles of the processed material, and also prevents injury to a person when a tool is destroyed, such as an abrasive disc.
Tool clamping nut. It can be unscrewed using a special key that comes with the power tool. There are also quick-locking nuts that can be unscrewed without a wrench.
The gearbox housing and the gearbox itself. Consists of a block of gears that transmit rotational movements from the rotor to the spindle with the tool.

The picture below shows electric diagram of the grinder.

The electrical part of the angle grinder has the following elements:

an electric cable with a plug for connecting to the mains;
start button;
stator;
electric brushes (carbon or graphite);
collector;
anchor (rotor).

The following figure shows grinder connection diagram, namely its engine.

All components of an electric motor perform specific functions.

Rotor - this is the shaft on which the coils and the collector are located. The rotor, rotating in the magnetic field of the stator, transmits the rotational motion to the angle grinder.
Collector... It is the part of the rotor to which all control cables are connected. Electrical signals from the control unit to the engine pass through the manifold. It is to the collector that the electric brushes are connected.
Electric brushes. Their main task is to transfer electric current from the power cable to the collector.
Stator. It is a coil with a certain number of turns. The task of the stator is to create a magnetic field, which, interacting with the armature, sets the latter in motion.

According to statistics, most cases of failure of angle grinders are associated with the electrical part of the apparatus. Some breakdowns may be minor, which allows you to repair the grinder yourself. But, for example, if the motor windings burn out, only a specialist can repair the angle grinder.

The reasons that the angle grinder does not turn on may be the following:

defective electrical plug;
defective electrical cable;
the start button has broken;
broken contact between the power cable and the button;
breakage of the contact wire of the electric brush;
strong wear of the electric brushes;
failure of the rotor or stator windings.

There may be different reasons for the angle grinder not picking up speed.

Breakage of the speed control unit... To test this version, it is necessary to connect the engine of the device directly, bypassing the regulator, and check the operation of the device.
Faulty electrical cable due to constant bending or mechanical damage. Because of this, the damaged wire begins to warm up under load, and the engine speed drops.
Dust contamination of the collector... Remove contamination with alcohol.
Brush problems... They may wear out or have a short contact wire, as shown in the following photo.

The brush, although half worn out, is quite functional. In this case, the short contact wire prevents the spring from pressing the electrode against the collector. This situation can also be the reason why the angle grinder stopped working in normal mode.

The reasons why the grinder is heating may be as follows.

Incorrect mode of operation of the device... As a result of overloads, the electric motor can become very hot, which often leads to burnout of the windings.
Bearing failurelocated at anchor. As a result, the rotor clings to the stator, the motor becomes difficult to operate, and the windings overheat. The problem is solved by replacing the bearings.
Clogged ventilation ductsthrough which air enters to cool the engine. It is necessary to clean the ventilation openings from dust.

Impeller breakage, which serves to cool the engine. It is installed on the rotor, on the side opposite to the collector. If the impeller is broken, it must be replaced with a new one.

Turn-to-turn closures stator and rotor windings. You will need to rewind the coils or replace these parts with new ones.

If you notice strong sparking when turning on the angle grinder in the place where the collector is located, then the reasons for this trouble may be as follows.

To diagnose the electrical part of the angle grinder, as well as eliminate mechanical damage to the device, you will need to disassemble it. Disassembly is carried out according to the following algorithm.

Unscrew the handle.

Remove the protective cover.

Open the special windows located on the sides of the casing of the angle grinder, and remove the electric brushes, having previously disconnected the terminals.

Unscrew the gearbox housing from the LBM motor housing.

Pull lightly on the gear housing and detach it from the housing. In this case, the gear unit will be removed together with the rotor.

After removing the armature, the motor stator will remain in the casing, which is also easily removed for diagnostics after unscrewing the fasteners.

To disassemble the gearbox, unscrew the screws holding the cover. Removing the cover reveals the gears of the reducer.

To remove the anchor from the grinder, you will need to unscrew the nut located inside the gearbox.

In order to remove the bearing from the armature, it is recommended to use a special puller. Otherwise, the shaft could be damaged.

As mentioned above, most often the angle grinder refuses to work due to breakdowns in the electrical part of the unit. For the correct diagnosis of the electrical circuits of the instrument, the repairmen of electrical equipment use a special device - tester.

If you pressed the start button of the unit and it does not work, then in 90% of cases the cause of the breakdown is not so serious that you cannot repair the grinder yourself.

Experts advise adhering to the basic rule of repairing a power tool: move from simple to complex.

The first step is to checking electrical cable and plug at its end. If it is collapsible, then unscrew it and check the reliability of the contacts. Otherwise, you will have to disassemble the grinder (remove the cover of the device) and “ring” the cable with a tester, and also make sure that the current goes to the contacts of the “Start” button. If the device shows a break, then the cable should be replaced with a new one.

The situation when the current flows to the button, but does not pass further (when the position is on), indicates switch malfunctions... The button cannot be repaired.It must be replaced with a new one, but first mark the removed contacts in order to connect them correctly in the future. If the contacts are incorrectly connected, the motor winding may burn out.

If during the check it turned out that both the cable and the start button are in good order, but no current flows to the brushes, then it is necessary to make cleaning the contact plates of the brush holders... If this procedure is ineffective, it is recommended to replace the brushes. Further, if everything is fine with the brushes, and the current flows to them, the rotor and stator should be checked for shorts and breaks.

The rotor of the electric motor may have the following malfunctions: interturn short circuit and wire breakage at the contacts of the lamellas. You can check the grinder's anchor with a multimeter: the device is switched to the resistance change mode, the value is set to 200 Ohm, and the resistance between two adjacent lamellas is measured with the help of probes. Thus, it is required to check all pairs of lamellas. If the resistance values are the same, then the rotor winding is not damaged. The detection of other resistance values during the “ringing out”, as well as the detection of an open circuit, indicates a malfunction in this coil. In this case, you will need to repair the grinder's anchor.

Usually, the rupture of conductors occurs at the junction with the winding. Inspect the places where the coils are connected to the lamellas, make sure that the soldering of the contacts is secure.

If you do not have a measuring device, then you can check the rotor by using 12 V light bulb and battery... The power should be between 30-40 watts. The check is done as follows: apply a voltage of 12 V from the battery to the plug of the angle grinder, connect a light bulb to the break of one wire, start rotating the spindle of the angle grinder. If the winding is in good condition, the light will burn evenly, without blinking. With an inter-turn closure, the degree of incandescence of the spiral of the light bulb will change. In this case, repairing the grinder's anchor with your own hands will be difficult, since the anchor winding scheme is quite complicated, and the process itself requires special equipment and knowledge. Therefore, it is recommended to entrust this operation to specialists. But the best way out of the situation would be to replace the anchor on the grinder with a new one.

If the light does not light up when testing the rotor, this indicates the presence of an open in the stator or a short circuit in its windings, as well as problems with the electric brushes.

To check the stator of the grinder, use, as in the previous case, a multimeter. The values you need set to 20-200 Ohm and do the following. Touch one probe to the contact of the stator winding, and the second to the body of the part. If the device shows resistance, it means that there has been a breakdown to the case. Touch the probes to the contacts of one winding, and then to the contacts of the other. If the resistance is the same, then the coils are serviceable. If the device shows an open circuit on one winding, it means that you will need to rewind the stator or replace the part with a new one.

It will be problematic to rewind the stator at home without special knowledge, skills and equipment. It is better to contact a specialist who is professionally engaged in motor rewinding.

Mechanical breakdowns of angle grinders include the following.Mechanical failures include breakage of the shaft retainer. In order to replace the retainer, you will need to disassemble the gearbox and remove the large gear.