How to replace the brushes on an electric screwdriver

How to Change Brushes on an Interskol Electric Screwdriver

All brush models of modern screwdrivers have one of two motor options. serviceable or maintenance-free. In the first case, each user can cope with the task. To replace the brushes on a DeWALT electric screwdriver will require:

  • remove the back cover;
  • disconnect the contacts from the brush holder;
  • Install new brushes to replace the worn brushes;
  • Clamp the contacts and reassemble the cover.

Many owners ask how to change the brushes on popular Makita 62 Series screwdrivers? They are equipped with maintenance-free motors, whose service life, according to the manufacturer, is comparable to the life of the brushes.

If necessary, the motor can be disassembled and parts can be replaced, which requires a number of highly precise and painstaking operations. The specialists of “Udachnaya Technica Service” workshops recommend in such a situation to replace the whole unit. the cost of the service is low, but the result is much more reliable than a makeshift repair.

One of the most popular and popular tools of home craftsmen is an electric screwdriver. Thanks to its mobility, power and versatility allows you to cope with any task of drilling holes and installing screws and self-tapping screws. Despite its obvious advantages, if a malfunction occurs, you can repair an electric screwdriver with your own hands or send it to specialized centers. For most users, the first option (with the study of some nuances) will be more acceptable, because it will avoid costs and save time

Before you start identifying faults and their elimination, it is necessary to read the operational documentation in detail, as well as pay attention to the design features of the specific model of the device


The main indications that the brushes on a Bosch, Skil, Ryobi, etc. electric screwdriver could need replacing.д. serve:

If the chuck won’t turn when you press the trigger, first of all check the battery. If it is okay, you need to take apart the housing of the tool and use a multimeter to determine the resistance between the brushes. if these elements are in good order it is close to 0. If it looks like an open circuit, it is best to knock on the brush holders and turn the rotor, otherwise you will know that repair is needed.

Bosch electric screwdriver sparks and smells

a 12 volt electric screwdriver on NiMH batteries has little power and needs to be replaced, but more on that later.

We disassemble the tool to see the cause, although it is clear. something with brushes or contact pads, i. e.к. sparks.

Electric screwdriver disassembles very easily, not to compare with the Chinese samples, unscrew the Allen screws, they can also be unscrewed with a flat screwdriver:

Take out the motor, just pull it out of the gearbox, the numbers from it 1 607 022 529, LS-550PX-62852, 110422 / B:

The motor cover is rolled up on 4 sides, so you have to flatten it:

Remove the cover, we see the plastic housing which holds the brushes:

Remove the two textolite washers and remove the brush unit:

But the contact group of the armature leaves a lot to be desired:

replace, brushes, electric, screwdriver

The pinion is forbidden, that’s why you can’t take out the armature, I guess:

Take sandpaper 800, you can finer and scrape the contact pad:

The fewer the ribs and craters, the better the contact and the less the spark.

Reassemble in reverse order, all is well, though at a sudden stop the spark slips.

Later I will clean contacts more thoroughly and wash brushes from grease.

And finally, the important note. do not immediately throw the trigger of an electric screwdriver to stop, do it slowly and then will not burn out the contact group of the motor.

Tags: 12V, Bosch, smells, sparks, electric screwdriver, brushes, armature

Sparks and odors coming out of the electric screwdriver

A common reason cited by owners when contacting Udachnaya Technika service centers is that a Bosch (Bosch), Metabo or other electric screwdriver sparks and smells when it is working. Often these phenomena are not signs of any malfunctions, but in any case timely consultation with a craftsman and preventive inspection will help to avoid serious damage and save a considerable sum on repairs or the purchase of a new instrument.

It is not unimportant for the life of a tool that has been subject to excessive sparking. It is perfectly normal for a new electric screwdriver to have sparks when operating. The sparks are caused by a permanent connection between the conductive brush and the collector contacts, separated from each other by a technological gap. In this case, slightly increased sparking passes after lapping brushes during the first 10-15 minutes of work tool.

It is important to find out why the brushes of an Interskol, Makita, etc. electric screwdriver are sparking.д., that has been in use for days, months, or even years. This can happen for the following reasons:

  • contamination of the collector contact pads with carbon deposits generated by high engine loads. To remove the fouling, you will need to carefully scrape the collector with the finest sandpaper;
  • accumulation of graphite dust in the gaps between the collector blades, which mainly occurs if the brushes are not positioned correctly due to backlash. Dust is gently removed mechanically with a sharp object;
  • if an electric screwdriver sparks inside and smokes at the same time. the high probability of presence of an intercircuit in the armature, which can be unmistakably detected by a special device that induces an alternating magnetic field. In this case, only a winding rewind or complete replacement of the armature (motor) will help.
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The reason why the electric screwdriver sparks when stopped is the presence of an electric brake in the model. It contributes to almost instantaneous stopping of the shaft, and appearance of sparks is considered normal.

To make sure that the tool is in good working order, to get prompt and inexpensive repair you can always in the workshops of “Udachnaya Technica Service”!

How to replace the brushes on an electric screwdriver

It is not uncommon for an electric screwdriver to have excessive brush wear on its electric motor. It is not difficult to rectify such a fault, but a minimum of knowledge of the DC motor is required. Let’s start by defining what brushes are.


Motor brushes are contacts through which current is supplied to the rotor windings. Since the rotor is designed to rotate, it is not possible to supply current to its windings through a fixed wire connection. The collector-brush assembly (BCA) is used for this purpose.

The collector consists of copper plates attached to an insulated section of the armature shaft. This is where the outputs of the rotor windings are connected. The brushes are mounted close to the collector. As the rotor rotates they slide over the collector plates. Through these sliding contacts in the armature windings the current flows alternately.

The alternating magnetic field produced by this is the force that turns the rotor.

Knowing how the assembly that powers the armature windings works, it is easy to guess that its parts must wear out. The rotor is a complex and expensive component. So in order to protect its collector from wear, the brush material is intentionally chosen to be less abrasion-resistant. Otherwise it wouldn’t be the brushes that would have to be replaced but the armature.

Another necessary property of the brushes is that they must have good electrical conductivity. A mixture of copper powder and graphite meets these conditions best. Electric motors with less power or a higher voltage than an electric screwdriver can be fitted with graphite brushes.

And for a small electric screwdriver motor with a lower operating voltage and higher currents graphite is not suitable because the electrical resistance is too high for it.

replace, brushes, electric, screwdriver

Important! Every serviced electric screwdriver is supplied with spare copper-graphite brushes.

If you can’t find them when you need them, use any appropriately sized ones made of the same material.

If you cannot make a precise selection, use a slightly larger set and match it with a medium-sized file. It is very easy to grind the small brass and graphite brushes.

Do not rush to disassemble the electric screwdriver if the chuck will not spin when you press the trigger. Start with an easy one. change the battery with a known good and fully charged one. If there is no change, remove the battery, remove the self-tapping screws from the housing, and disassemble it.

Use a multimeter to measure the resistance between the brushes. If they are no more worn than the allowable, they will have good contact with the collector, and the gauge will show a resistance close to 0.

If the readings look more like an open circuit than a short circuit, tap the brush holders with a screwdriver handle and turn the motor rotor several times by hand. Unchanged readings of the tester will indicate that the contact has not been restored, and the tool requires repair.

Replacing Carbon Brushes in a 12 Volt DC Motor or 775 motor/775 Dc motor

It is easier to do this check than to disassemble the motor, especially an unattended one. Note that the symptoms of armature winding breakage and worn brushes are the same. But winding breakage is a very rare event, while wear and tear is much more common.


Maintenance-free motor is characterized by a rolled back end of the brackets. Often, and the cover on the inside where they are, inserted into the housing, is secured by rolling. The process here is a little more complicated.

  • Use a pair of pliers to bend the flare that holds the cover
  • Mark three points equidistant from each other on the perimeter of the cover and housing
  • Remove the cover
  • Using solder grease, solder, and a high-powered soldering iron, tin the intended points
  • Cut multicore wires and replace worn brushes with new ones
  • Solder the wires leading from them to the holders. After that, not to break the copper-graphite contacts while installing the cover, sink them into the holders one by one and fix each of them in this position with a thread, tying it with a bow
  • Leaving the ends of the threads on the outside, place the cover in the case
  • Re-establish contact in the control room by untwisting and pulling strands
  • Solder the cover to the motor housing

About the labor involved

Repairing an electric screwdriver with a serviceable motor can be done relatively quickly. You can’t repair a machine that can’t be repaired. Think maybe in the time it takes to repair, you can earn enough money to buy a new one by doing what you’re good at. After all, you don’t have to learn something to do it just 1 time.

Disassembling the screwdriver

often than not, in order to troubleshoot and repair the device, you will need to disassemble it. Since all devices look similar, resembling the shape of a gun, their disassembly can be represented as recommendations given for Interskol screwdriver repair:

  • First of all the battery pack is disconnected. To do this, you need to press the latch and unfasten the module.
  • All screws around the perimeter of the unit are removed using a Phillips screwdriver.
  • After unscrewing the screws, the two halves of the body are separated, while adhering to the parts of the design installed in the grooves.
  • Carefully disconnect the speed selector, the start button and the reversing mechanism.
  • The reducer is taken out of the removed half. To remove it, you need to rotate the gearbox in its seat.
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Assemble in the reverse order. It is necessary to ensure that all removed elements and wires are located in the recesses made specifically for them.

To lubricate or oil the mechanical parts or to restore the gearbox, the latter often has to be disassembled. To do this, first remove the protective plate, then unscrew the screws in a circle, and remove the top cover. Viscous materials such as Lithol are used as a lubricant

It is important to note that serious repair of the screwdriver gear with their own hands to spend almost impossible, as separately gears are not produced by the manufacturers. Therefore, if it is damaged, the whole unit must be replaced

The next element to be dismantled is the chuck. It is a quick-action piece that is fastened with a screwdriver, bolt or Morse cone. The first method requires using an Allen wrench to unscrew the fastener, and then, inserting the wrench into the chuck, tightly clamp it. The chuck is unscrewed with the wrench.

In the second type of connection with a screwdriver counterclockwise, unscrew the screw, located in the middle of the jaws of the cartridge. Then, having set and clamped in the jaws of the wrench of g-shape, sharply turn it counter-clockwise. Removal of the fastener using the Morse taper is accomplished by carefully striking the face of the chuck.

Electric Screwdriver Motor Repair

If you work with an electric screwdriver for a long time, the bearings can get worn out or blocked.

Before you begin assembling the electric motor of an electric screwdriver with a thin wire, which serves as a clamp, in a brush holder each brush is withdrawn, the cover is set in its former place. In doing so, the brushes are released and wrap around the edges of the housing, which helps to best hold the back cover.

If the electric screwdriver works for a long time, it may be accompanied by a process of distortion of the shaft relating to the gearbox due to heavy loads and pressure on the tool. The chuck screwed onto the shaft can sometimes cause the unit to run wildly unevenly. The shaft support sleeve or bearing may be excessively worn. As a result of damage to the bushing or only the bearing and not the shaft is replaced.

Sometimes the engine cannot be started for a certain fraction of a second, i.e., it stops abruptly. Gearbox failure could be the cause. Often the malfunction is due to a broken pin that serves as a fixture to the satellites. Replacement of the driver or the whole gearbox may be possible, which may fail if the gear teeth are worn.

If after carrying out the above operations no malfunctions are found in the unit, it is necessary to check the condition of the armature and the motor brushes. The motor should be disconnected from the switch button and then the resistance should be measured by connecting a tester of any kind to the motor wires. If there is no resistance in the circuit completely, it may be an indication that the brushes are worn out. Faults in the motor armature in this case are not excluded, which can be associated with a break in the winding. However, these types of faults can be rare.

If the motor armature is completely burned out, the unit’s motor is to be completely replaced. If only the motor brushes are worn out, it is better to repair the appliance yourself. Before beginning the repair, the motor housing of the electric screwdriver should be opened gently so as not to damage its edges. All the steps to perform work related to the replacement of the brushes are indicated above. It is possible that the armature bushings have been worn by the magnet, which has come loose and become in contact with the armature. After dropping a drop of special oil on the bushing, the motor should be shut down to wait for the oil to disperse over all the bushings. However, it still requires replacement over time.

Common malfunctions and their causes

Because of the special working principle, these parts regularly fail. They are always rubbing against the collector when they are working, and as a result, they wear out. Household screwdrivers that have quality manufactured graphite parts are made so that they wear out as slowly as possible. In a tool that is little used, critical wear and tear occurs on rare occasions. Worn brushes stop making contact with the manifold.

Sometimes there is a break in the circuit that causes the motor not to start at all. If the brushes get jammed in the guides and the spring is not able to press them well against the manifold, they begin to hang.

The following breakdowns can be visually detected:

For an electric screwdriver, their sparking is very dangerous, which occurs because dirt and soot builds up on the collector. Need to be cleaned with zero-grit sandpaper. Contacts are shorted due to a build up of copper powder or graphite dust. Everything is removed with any sharp object, a knife is fine.

Brush changes are often necessary with regular use of an electric screwdriver

Sparking will be observed if the contacts differ in resistance level and the brushes are not properly matched to the main parameters. Even properly matched parts need some time to fiddle with. Professionals recommend running the engine at idle with no load. The manifold must be cleaned regularly. Special lubricants are used to extend the life of an electric screwdriver.

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Find the cause of the malfunction and fix it

The final failure of the tool is often accompanied by preliminary events, paying attention to which it is possible to prevent serious malfunction: the occurrence of extraneous sounds, sparks, burning odors, increased vibration, rapid discharge of the battery.

replace, brushes, electric, screwdriver

If you disassemble the device you will be able to see which component is defective. All malfunctions of the device are divided into two types:

Each type is characterized by its primary signs, which can easily identify the damaged part. Faults associated with the battery are of a special type. The nature of the failure is related to the fact that the battery discharges quickly, or the device does not want to start at all.

If buying a new battery is problematic, you can try to take it apart and replace the defective element in it.

The battery is disassembled by pulling its latches out of their slots. Under the casing are the cells with a capacity. Their connection between them is made by means of contact welding. You can measure the voltage of each bank with a multimeter. The normal value of a charged cell is 1.2 volts. Faulty cells are removed. to do this, they are carefully bitten off with wire cutters at the point of contact, and similar ones are installed in their place. If there is no welding, it is possible to use a soldering iron. Then assemble the battery and put it in the screwdriver for testing.

But the battery is not always the problem. For example, when repairing a Bosch screwdriver with your own hands, it is not uncommon to find damage to the battery charger circuitry (battery charger) rather than the battery. The repair of the battery charger consists in the testing of the radio elements. The mains fuse and the rectifier bridge are checked first.

Usually when you open the case of SA by external signs in the form of blackening of radio elements or board textolite it is immediately visible which element needs to be replaced. the most frequent causes of damage are transistors located on the radiator and the operational amplifier.

Electrical Damage

The most common electrical problems are not only the inability to start the tool but also the inability to switch into reverse or adjust the RPM.

If the battery is intact, and when connected to the circuit of the screwdriver, the voltage at its terminals drops, then it indicates a malfunction in the elements of the motor of the device. If the voltage is normal, check the button. To do so, switch the tester to the continuity mode and set its probes parallel to the button. If this is pressed, the multimeter should make a beep, otherwise the button is inoperative. You can try to repair the part yourself by cleaning its contact groups.

Checking the reverse is also done using a multimeter. Touch the button input with one probe and the motor contact with the other. When reversing, there should be a resistance; if there is no resistance, then the damage should be in the wiring. If the engine rpm control does not work, then the fault is in the control transistor or button.

Check the brushes of the electric motor visually, their wear should not be more than 60. If nothing is wrong, check the other motor elements. To measure the resistance of the windings, the motor contacts must be disconnected from the rest of the circuit. If a break, an inter-turn or a short to ground occurs, the winding has to be rewound. This is also the way to check the armature. To measure its resistance, the tester probes are placed on the manifold plates. The resistance value must be zero. If the winding can not be repaired, you must buy a new motor.

Arcing and crackling during operation are also electrical faults. This is caused by worn brushes or a slow rotation of the collector due to a blockage.

Malfunctions in mechanical units

If you hear noises during operation and the device wedges, the bushings or bearings are worn. After disassembling the gearbox it will become clear what might be broken. Unusual noises can also be caused by a shaft deflection. Such a breakdown also occurs with the runout of the chuck. If there is any looseness in the chuck, the socket must be checked for wear. As the tool is running, the teeth wear out and the clutch begins to rotate.

To avoid damage to the gearbox, you need to periodically service it. To do this, it is advisable to lubricate all moving mechanical parts, preferably beforehand removing any residues of old grease. Clogged construction can also affect the speed of the tool.

replace, brushes, electric, screwdriver

How To. Replace Worn Power Drill Brushes

Extraneous sounds can be characteristic not only because of damage to the gearbox, but also be caused by the engine. Noise is caused by a torn magnet or worn armature bushings. To re-install the armature, you can try oiling it with machine oil.

Thus, in the case of mechanical breakdowns, the cause is easy to find, but carrying out repairs will require the purchase of new components to replace the broken ones. To find electrical faults you will need to use a multimeter.

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