In detail: screwdriver Makita do-it-yourself repair from a real master for the site my.housecope.com.
One of the most "popular" tools of the home craftsman is a screwdriver. But, like any product, it breaks down. What to do in this case? In some types of work, an electric drill can save the situation, but only in some. You can take the tool to a service center and wait for it to be repaired. But this will take time and money, which will have to be paid to repair the instrument. But, as a rule, the third option is also available - the repair of the Makit screwdriver, and the device of the screwdriver is not so complicated.
Let's look at the main symptoms of screwdriver malfunctions and how you can fix them at home on your own.
Before proceeding directly to the malfunctions of this tool, it would be nice to briefly get acquainted with the device of the screwdriver and the purpose of its main units. Let's start with this. The photo below shows a disassembled screwdriver, on its basis and consider the purpose of the parts.
We'll start with the start button. The button has two functions: turning on the power supply circuit of the electric motor and its speed regulator. When the button is pressed all the way, the motor power circuit is closed by the button contacts to a straight line, providing maximum power and number of revolutions. The speed controller is electronic, it consists of a PWM generator located on the board. Depending on the force of pressing the button, the contact located on the button moves along the board. The degree of the generated pulse per key depends on its location along the board, the role of the key is played by a field-effect transistor (in the photo above it is designated as a "rotation speed regulator"). That is, the dependence is as follows: the harder the user presses the button, the higher the value of the pulse on the transistor and the more it opens, thereby increasing the voltage on the electric motor.
Video (click to play).
Motor rotation is reversed by reversing the polarity at the terminals. Reversal of polarity is carried out by means of changeover contacts, which are flipped by the user using the reverse handle.
Electric motor. In this tool, as a rule, single-phase DC collector motors are used. They are characterized by reliability, ease of production and maintenance. The design of such a motor is as follows: a body on which magnets, an anchor and brushes are located.
Reducer. Its purpose is to convert a large number of revolutions of the motor shaft into significantly lower revolutions of the chuck shaft. There are two types of screwdriver gearboxes: planetary and classic. The latter is very rarely used, so we will pay attention to the planetary type gearbox. The planetary gearbox consists of:
ring gear;
sun gear, which is attached to the shaft of the electric motor;
satellites and a carrier (their number depends on the number of steps, there are two or three steps).
Without going into subtleties, let's consider the principle of operation of such a gearbox. The sun gear is driven by the armature shaft, in turn, its teeth drive the satellites, which transmit the rotation of the carrier. With a two-stage gearbox, the chuck shaft is connected to the second carrier, with a three-stage gearbox - with the third.
The force regulator is designed to adjust the force that is applied to the screw. As a rule, 16 adjustment positions are used. Thus, there is a wide range of screw tightening levels, which allows you to work with very fragile materials (drywall, etc.). Its principle of operation is well illustrated in the video below.
The chuck is attached to the output shaft of the gearbox and has three cams that securely hold the part in the chuck.
VIDEO Having considered the main elements of the screwdriver, let's move on to possible malfunctions and possible ways to repair the AEG screwdriver. And we'll start with the electrical part. The main signs of a malfunction of the electrical component of the screwdriver are:
the instrument does not turn on;
no reverse mode switching;
there is no adjustment of the number of revolutions.
The instrument does not turn on. The first thing to look out for when repairing a Skil screwdriver is the battery. If we put it on charging, and it did not help, then we arm ourselves with a multimeter and proceed to troubleshooting. To begin with, we measure the voltage on the battery, it should more or less correspond to the one indicated on the battery case. If the voltage is too low, it is necessary to identify the faulty element: a battery or a charger.
You can determine the health of the charger with a multimeter, for this we plug it into the network and measure the voltage at idle at the terminals. It should be a couple of volts more from the nominal indicated on the device. If there is no voltage, the charging unit is faulty. For such a repair of the Interskol screwdriver, knowledge of electronics will be required, otherwise it is easier to buy a new one.
If there is a problem with the battery, then to repair the Makit screwdriver with your own hands, you need to open the block with the elements. After the unit has been disassembled, it is necessary to carefully examine all the wire connections and check the quality of the soldering, whether any one has come off. If all connections are intact, we take a multimeter and measure the voltage across each element. Each element must have at least 0.9 - 1V voltage. If an element with a lower voltage is found, it must be replaced. The main thing is that the capacity and type of the cell correspond to the rest (i.e. if NiCd, then NiCd is also needed). You can learn more about the repair of batteries from the article: "Do-it-yourself screwdriver battery repair."
If the charger and the battery are in good order, and the screwdriver does not turn on, it is necessary to disassemble the screwdriver. Two wires go from the battery terminals to the button, we take a multimeter and measure the voltage at the input of the button (the battery is inserted in this case). If there is voltage at the input, then we take out the battery and with the help of the crocodile clips we short-circuit the wires from the battery. We put the device to measure resistance in ohms. Press the button all the way and measure at the exit from the button. The device should show the value of resistance tending to zero, if it is - the button is working properly, the problem is either in the brushes or in other elements of the electric motor. If the tester shows an open circuit, the button needs to be replaced or repaired. You can try to repair it yourself, as it often happens that there is no contact on the terminals due to burning, it will be enough to clean it with sandpaper and assemble it. The main thing when parsing a button is not to rush and act carefully, otherwise all the parts will fly apart, and you will have to puzzle for more than one hour how to assemble it.
Similar actions will need to be taken in the absence of reverse. We put one probe of the device on the input wire of the button, the second on the contact of the electric motor or the output of the button, this is more convenient. We switch the reverse handle. If everything is working properly, the device will fix a certain amount of resistance, if it is “silent”, the conductivity of the reverse contacts is broken. The procedure for disassembling and cleaning the contacts is the same as described above, as when repairing the Caliber screwdriver.
Is the engine running at maximum rpm and there is no rpm control? The cause of the malfunction can be both in the button itself and in the regulating transistor.
If all circuits to the electric motor are in good order, but the tool does not work, the malfunction may be associated with the brushes.Ideally, brushes should be changed when they are long, worn 40% of their original length. If the brushes are worn, replace them with new ones; if the brushes are in order, the problem is with the rest of the motor elements. To check the electric motor, you must disconnect the wires that go from the button. After disconnecting the wires, using a multimeter, we measure the resistance value at the wires fastening contacts. If the resistance value is small and tends to zero, most likely a winding break has occurred, either rewinding or a new motor is needed.
You can check the integrity of the armature windings, since the armature can be bought and changed on your own. To check the armature, it is necessary to measure the resistance on two adjacent collector plates, along the entire circumference. In this case, the normal value is "0". If during the check you find two adjacent plates, with a value other than zero, the anchor needs repair or replacement.
VIDEO
Signs of a malfunction of the mechanical part of the screwdriver may be the following:
during operation, the instrument emits extraneous sounds that were not previously observed;
strong vibration of the tool and chuck breakage;
the screwdriver turns on, but its further work is impossible due to jamming.
The reasons for "extraneous" sounds during the operation of the tool may be the wear of the bushings or the armature bearing. To do this, it is necessary to disassemble the electric motor and examine it for bearing integrity and the degree of bushing wear. The anchor should rotate easily, without friction and distortion. If necessary, these items can be purchased at the store and replaced by yourself.
The most common gearbox malfunctions are:
bending of the gearbox shaft;
wear of the working surface of the gears;
wear of the bearing and / or bearing sleeve of the gearbox shaft;
break in the pin on which the satellite is attached.
In all cases, it is necessary to replace defective gearbox parts. All described actions require attention and sequence in disassembling and assembling the screwdriver. Having shown these qualities, you can independently repair the Interskol screwdriver with your own hands, or any other, and only in some cases resort to the help of the service center.
VIDEO
Repair or installation of furniture is in full swing, and the screwdriver has stopped working. Consider the main causes of breakdowns and how to repair a screwdriver with your own hands (the video will also help us with this). To answer the question why the screwdriver does not work, and how to repair it, you need to have an idea about the device of the screwdriver, its main units, among which the following can be distinguished: a gearbox, a reversing device, an electric motor, a speed regulator, and if the tool is autonomous - a battery (battery charger battery).
Moreover, both expensive and cheaper screwdrivers basically have a similar device, which differs from each other by the presence of certain advanced options. From here, we can single out the main reasons why the screwdriver does not work, which almost all models suffer to one degree or another:
The first thing you need to pay attention to is the health of the battery or the breakdown of the electrical cable from the network (mains screwdriver).
Failure of the trigger button of the tool.
The engine speed is not regulated or poorly regulated.
Impossibility of reverse switching.
Chuck runout.
The electric motor does not rotate.
Everyone understands that regardless of the "steepness" of the hammer drill without an energy source, its work is impossible. Therefore, first of all, you need to check the serviceability of the battery if your hammer drill is mobile and does not depend on the power source. The main reason for the inoperability of a battery is its discharge or long-term use. The second reason is eliminated by a complete replacement of the battery, and the first by a simple recharging using the rectifier supplied with the sale of the instrument.
Screwdriver battery disassembled
As a rule, two batteries are included in the same kit: one is in action, that is, in operation, and the other is being recharged. In case of failure of the charger, it will be more rational to replace it with a new one, unless, of course, you are an expert in radio electronics.
If you are the owner of a power screwdriver, first of all, if the motor does not rotate, check the entire chain of the electric drive: the socket, the cable plug and the cable itself. Believe me, it often happens that the socket fails (contacts burn out), the cable plug may fail for the same reasons, and the cable itself can be damaged as a result of careless handling.
As a result of long-term operation of the tool, as well as the conditions in which it is necessary to use it, there are often cases when the start button of the screwdriver fails - this is also one of the reasons why the screwdriver does not work. The problem is solved by purchasing a new trigger mechanism in the store and replacing it with an old, faulty one.
Start button (red) of the screwdriver
It is not difficult to get to the failed start button: you need to unscrew all the self-tapping screws connecting the two halves of the tool body using a Phillips screwdriver. Next, using an electric soldering iron, disconnect the wires of the button from the electric motor, disconnect the terminals connecting the button with the battery or the mains power cable and remove the problem from the case. In its place we insert a new button, carry out the connection process in reverse order and check the operation of the new part by connecting it to the battery or power cable.
Stages of disassembling the screwdriver button
Sometimes in stores it is impossible to buy a new start button and you have to restore it yourself. However, we will not describe this entire process in detail for two reasons: firstly, the Internet is full of articles on this topic, and secondly, repairing the trigger button with your own hands is not the topic of our article. Therefore, we will move on.
The lack of adjustment of the screwdriver's engine speed significantly reduces the convenience when working with the tool, and also makes it impossible to perform high-quality work. The regulator is located in close proximity to the start button or is made with it as a whole, however, the transistor of the speed regulator is attached to the electric motor where it is cooled through the radiator grilles.
The location of the regulator of turns of the electric motor (7)
As practice shows, in the event of a similar problem, it would be more correct to replace the speed controller completely with a new one. Fortunately, they are on sale and are relatively inexpensive. All attempts to repair it led to the same conclusion, unless, of course, you are not an expert in the field of electrical engineering.
The screwdriver's reversing switch plays an important role when performing work on screwing in self-tapping screws, as well as removing them if necessary. The electric motor reverse circuit is located in the same housing with the speed controller, and the speed redirection switch itself is located in a convenient place on the handle.
Start and reverse buttons located side by side
Switching is carried out by changing the polarity on the terminals by moving the reverse button. Repairing the entire reverse circuit, including the PWM generator located on the board, boils down to cleaning the switch contacts and replacing the reverse circuit with a new one.
The runout of the screwdriver chuck indicates that there is a problem with the gearbox of the tool, which is located just behind the electric motor. This is another reason why a full recoil screwdriver does not work.
Screwdriver Planetary Gearbox Parts
The output shaft of this gearbox is the place where the chuck is attached, so if we talk about the runout of the chuck itself, you need to keep in mind the runout of the gearbox shaft. The reasons for this may be the following:
a) bending of the gearbox shaft;
b) wear of the gears of the reducer;
c) failure of the support bearing of the gearbox shaft;
d) the limiting development of the pins, on which the planetary gear satellites are attached.
All of the above parts are of factory origin and cannot be repaired. In this case, the problem of the beating of the screwdriver chuck is solved by replacing the gearbox parts with new ones.
Malfunctions of a screwdriver electric motor are not much different from similar problems with a grinder, drill and other power tool. The first thing that can be the reason why the screwdriver does not work is the wear of the electric motor brushes, which can be easily replaced with new ones that are not very expensive. The second reason is the failure of the armature or stator winding of the motor.
The appearance of the electric motor of the screwdriver
Most often, an interturn short circuit occurs due to a violation of the insulation of the winding wires. A short circuit can occur due to overheating of the electric motor from, so to speak, overwork, that is, you need to let the tool cool down in time, give it a "rest".
By the way, overheating of the screwdriver can lead to leakage of lubricant from the gearbox, which will result in the failure of its main parts, which were mentioned above.
Another problem can be observed in the armature of the electric motor: contamination or oiling of the collector, which transfers electricity to the motor from the brushes.
Electric motor brushes and screwdriver
The collector can be repaired at home on your own by rinsing and cleaning it with fine emery cloth. But the stator and armature windings will have to be restored in a specialized workshop or the motor will have to be completely replaced with a new one.
In conclusion, I would like to note that the screwdriver will work for a long time and with high quality if you treat it carefully, without showing "fanaticism" during its operation.
VIDEO VIDEO
The screwdriver can be safely ranked as a tool that quite often has to be used not only in everyday life, but also for work on construction sites. But, like any complex technical accessory, the product can break. We will consider how to repair a screwdriver on our own in this text.
The equipment in the construction market, where screwdrivers take a separate place, is quite large. Many models have individual criteria, assembly quality and cost. However, most of the models are characterized by basic principles of operation and internal execution.
The basic elements of any screwdriver include:
the presence of an electric motor;
planetary reductor;
adjustable function button "Start";
reverse switch;
effort regulator;
power unit.
The electric motor is powered by a direct current network, structurally represented by a cylindrical shape. Inside is an anchor with brushes and magnets. The peculiarity of the electrical circuit of the motor assumes that the direction of the supply voltage flow will be directed to the brushes. When the supplied polarity changes, the motor reverses.
The planetary gearbox is an important element capable of converting the high-frequency vibrations of the electric motor shaft into the low-frequency revolutions of the chuck shaft. Typically, these parts are manufactured from wear-resistant plastic or metal. Many screwdrivers are equipped with 2 speed gearboxes. Switching to the first speed mode is necessary for working with self-tapping screws, and at the second speed you can drill into wood, plastic base or metal.
The "Start" button starts the device.It is able to control the number of revolutions, providing the ability to select the optimal rotation speed for the chuck shaft. Correspondingly, pressing forcefully will power the engine at high rpm, and as the pressing force decreases, the power criterion will weaken.
The reverse switch is required to carry out operations to change the rotational direction of the screwdriver motor. This functionality is convenient to use not only for tightening, but also for unscrewing screws.
Regarding the force regulator, we can say that it determines the speed of tightening the screws. In current models, a 16-step adjustable graduation is provided, which allows you to determine with maximum accuracy and convenience what tightening speed is relevant when working with various materials.
The power source of the screwdriver is the rechargeable batteries of the overall size, where the power supply voltage (depending on the device model) can vary from 9 to 18V.
VIDEO
the breakdown is associated with the electronics of the device;
breakage can be mechanical.
Understanding the objective causes of electrical breakdown, one can note its characteristic signs:
the product stops responding to switching on;
the device has ceased to regulate the speed;
the reverse operation failed.
Mechanical problems with a screwdriver include problems with wear of internal parts, for example, a characteristic ratchet of the mechanism is heard. As a rule, a faulty screwdriver will begin to make characteristic sounds, where, for example, bushings have been worn out or a bearing has collapsed. This often happens on a hummer instrument.
VIDEO
For example, if the tool stops turning on, then initially you need to check the health of the battery. If, when basing the device on charging, the breakdown has not disappeared, then you will have to arm yourself with a multimeter and start scanning the device in search of the root cause. First of all, take a look at the voltage value indicated on the device case and compare it with the measurement readings on the battery. The data should be roughly the same. If the voltage is too low, then most likely the problem is hidden in the charger or battery pack.
For example, the charger can be checked using a multimeter, plugging it into the network, and taking measurements at the terminals of the device at idle. It is important that the voltage criterion is slightly higher than the nominal one. In a situation where there is no voltage, then, unambiguously, the culprit of the breakdown is the charging unit. Interskol screwdrivers "suffer" from this rather frequent problem. In general, fixing the defect will require specific knowledge of electronics or a new unit will need to be purchased.
If you find a battery problem, for example, with a Makit screwdriver, you can open this block with your own hands, where the supply elements are located. As a result of opening, research of the connecting wires should be carried out and the quality of the soldering should be ensured. If no visible defects are found, then using a scanner, you should measure the voltage in each element. Values should indicate 0.9 - 1V voltage power. If a block with a low voltage indicator is found in a row, then it must be replaced.
VIDEO
Quite often, problems with buttons are associated with poor contact at the terminals. You can simply perform the procedure for cleaning the contacts with sandpaper and the problem will be solved. The main thing is to do everything carefully in the process of disassembling and assembling the device, without losing parts.
A broken gearbox is one of the mechanical problems with a screwdriver. Some of the most common problems with the reduction unit include:
physical curvature of the axis of the reduction shaft;
obvious defect of the working surface of the gears;
failure of the shaft support sleeve or original bearing;
breakage of the pin where the satellites are fixed.
To correct these defects, it will be necessary to physically replace the defective parts, therefore, this type of repair should be entrusted to qualified specialists who are able to correctly and accurately diagnose the breakdown and eliminate it.
VIDEO
In this article, we will consider a screwdriver from the well-known Makita brand, describe its technical characteristics and general structure, talk about the main problems and malfunctions that arise during the operation of the tool, as well as how to diagnose a breakdown and repair one or another element with our own hands. screwdriver.
VIDEO
The Makita company produces various power tools, among which there are screwdrivers. The company began its history from the beginning of the 20th century, and to this day it continues to delight consumers with its high quality goods. Let's take a look at the general features and characteristics of the models of this company.
Makita screwdrivers are very powerful. The average stroke rate for various models is about 2300 rpm, which is a good indicator compared to other brands. The weight of most models of tools is within 1.5 kg. Its small mass means that it will be comfortable to work with such a tool. The manufacturer also took care of the convenience of working in poorly lit rooms, making LED backlighting for most models. Separately, it is worth highlighting the type of handle for holding these tools on the weight. As a rule, they are made rubberized, and therefore it is convenient to hold them in a brush, respectively, the work process is much easier.
The disadvantage of these screwdrivers is the strong vibration of the handle during operation, as well as their short-lived batteries. In addition, the price for the products of this company is quite high, which is important for the domestic consumer.
Consider the device of a screwdriver on a specific model 6271D. The diagram of this model is shown in the figure below.
The diagram shows:
Shift lever
Body assembly
Nameplate
Screw
Spring
Reverse shift lever
Start button
Contact terminal
Screw
Keyless chuck
Gearbox assembly
Electric motor
Screw
Body assembly
Charging unit
Battery
A modern screwdriver is a high-tech device. Important structural elements:
Removable battery
Rubberized handle grip
Powerful electric motor
Metal planetary gearbox
Soft start button
Reverse switch button
Torque regulator
These are the main components of the screwdriver design, which are included in the basic package of any screwdriver model.
To disassemble the screwdriver, you need a Phillips screwdriver and some personal time.To disassemble the screwdriver completely, you need:
unscrew the screws securing the case;
remove the composite start button mechanism;
remove the electric motor together with the gearbox;
disconnect the gearbox from the engine by unscrewing the bolts holding them together.
To disassemble the battery of a screwdriver, you need to loosen the bolts connecting the body, or separate the body joints on an adhesive basis using a soldering iron. Inside the battery there are several nickel-cadmium batteries with a certain capacity and carrying a charge. In case of battery repair, they need to be replaced with new ones.
The chuck is changed with a screwdriver and a hex wrench. First, use a screwdriver to loosen the fixing screw in the chuck by turning it clockwise. Then the hexagon is inserted, the reverse button is turned on, clamped, and then the chuck easily yields.
VIDEO
The most frequent breakdowns of a Makita screwdriver are as follows:
The screwdriver does not turn on. Here and so everything is clear. The first step is to inspect the battery, as well as the contacts and connections in the case, and the wiring. A multimeter will help you to check.
The reverse button does not work. This means that you cannot either tighten or remove screws and bolts. Here you have to test the resistance of the button with a multimeter by placing test leads on the input and output wires of the button.
The speed regulator does not work. In this case, the revolutions will be either constantly reduced or constantly overestimated. The regulating transistor or brushes may be to blame. A visual inspection of the parts is required.
The on / off button of the instrument is a complex electronic mechanism. It consists of several elements that make it up:
start buttons;
reverse buttons;
buttons for switching the speed of revolutions;
buttons for soft start of the engine.
When repairing a button, you first need to disassemble it by unscrewing the screws that secure the case and disconnecting the battery. After that, you must check the connections and contacts for dirt, clean them. If cleaning the contacts did not help to fix the problem, the button should be replaced as a whole.
When repairing the charger, it is necessary to unscrew the screws securing the housing covers. Inside there is a printed circuit board with contacts. First you need to check the transformer with a tester. To do this, you need to measure the voltage at the output. Then the cable should be ringed to exclude its fracture. Then the primary and secondary windings of the transformer and the fuse are checked. You need to assemble it in the reverse order.
VIDEO
When repairing the battery with a Phillips screwdriver, unscrew the screws that secure the case. There are several cans inside the case. Visual inspection should be used to inspect them and detect abnormalities in geometry such as bulging, for example. We test the banks with a multimeter for residual charge. If it is absent, the bank is replaced with a new one.
VIDEO
To remove the gearbox, you need to disassemble the case by unscrewing the screws with a Phillips screwdriver. We take out the start button, the reverse switch button, disconnect the bolts of the engine to the gearbox. Then you need to take out the contents of the gearbox (various gears), the speed selector washer. When examining an empty gearbox, special attention should be paid to the teeth located around the circumference of the gearbox housing. If they are worn out, the gearbox will not be able to fulfill its function: the speed switch will not work correctly. To restore the teeth, it is necessary to use small bolts, inserting them in place of the original plastic ones. The gearbox must be assembled in the reverse order. The gearbox diagram is shown in the figure below. It shows a general diagram of the gearbox.
The brushes used for the screwdriver are graphite-based. Their cost today varies between 2–5 USD. e.They are located in the motor housing and are two graphite cubes fixed on metal plates. With intensive work, they wear out and wear out.
When repairing with your own hands, you can file them out of brushes from another tool, for example, a car starter. After grooving, they should be inserted into the brush holder and put in place by assembling the motor.
VIDEO
Such a chuck is used for clamping bits with a cylindrical shank. This cartridge features ease of installation. It is installed literally with one movement of the hand. It is used for drills with a diameter of one to ten millimeters. It is a movable structural member in the tool and therefore breaks frequently. To disassemble it, you need to read the tips described at the beginning of the article for disassembling the cartridge using a hex wrench and a Phillips screwdriver. The price of this product is about $ 20. e.
The material in this article is voluminous. Here we described all the possible problems that arise during the operation of Makita screwdrivers, told how to eliminate them on our own, separately talked about the various structural elements that make up the basis of any screwdriver. The materials of the article show the diagrams of the gearbox and the general device of the screwdriver. We hope that the information will be useful to you.
VIDEO
One of the most sought-after tools for home craftsmen is the screwdriver. However, this device sometimes breaks, like any other. If this happens, in some cases you can replace this tool with an electric drill. If work cannot be done with an electric drill, you will need to take the screwdriver to a service center in order for specialists to repair the tool. However, this can be time-consuming and costly. Therefore, you can use another option - do it yourself repair the screwdriver.
Screwdrivers are commonly used to assemble furniture both at home and in production.
Before making repair work, you will need to familiarize yourself with the design of this device. In fig. 1 you can see this tool exploded.
Elements that are needed in order to make a screwdriver:
multimeter;
clamps;
sandpaper;
spare parts.
Figure 1. The device of the screwdriver.
The main element is the start button, which performs several functions: turning on the power supply circuit of the electric motor and the speed governor. If the button is pressed all the way, the motor power circuit will be closed by contacts, as a result of which the maximum power will be provided. The number of revolutions in this case will also be the maximum possible. An electronic regulator is installed in the device, which consists of a PWM generator. This element is located on the board. The contact that is placed on the button will move along the board depending on the pressure on the button. The level of the adjustable impulse per key will depend on the placement of the element. A field-effect transistor is used as a key. The principle of operation will be as follows: the more the master presses the button, the greater the value of the pulse on the transistor and the more it will open and increase the voltage on the electric motor.
The reverse of the rotation of the electric motor will be carried out by changing the polarity at the terminals. This process is carried out using contacts that will be thrown by the master using the reverse handle.
Charger device for cordless screwdriver.
In screwdrivers, in most cases, single-phase continuous current collector motors are installed. They are reliable and easy to manufacture and maintain. An ordinary screwdriver consists of the following elements:
The gear structure will convert the high speed of the electric motor shaft to the low speed of the chuck shaft.Screwdrivers can have planetary or classic gearboxes. The latter are rarely used. Planetary devices consist of the following elements:
ring gear;
sun gear;
satellites;
drove.
The sun gear works by means of the armature shaft, its teeth drive the satellites that rotate the carrier.
A special regulator is used to regulate the forces that will be applied to the screw. Most often, 15 adjustment positions are used.
The main signs of a malfunction in this case will be:
the screwdriver does not turn on;
it is impossible to switch the reverse mode;
it is impossible to adjust the number of revolutions.
Diagram of the gearbox of the cordless screwdriver.
The first step is to check the screwdriver's battery. If the tool was put on charge, but this did not help, then you will need to prepare a multimeter and try to find the malfunction with it. First you need to measure the voltage on the battery. This value should approximately correspond to the one indicated on the case. If there is an underestimated voltage, then it will be necessary to identify the faulty element: a battery or a charging device. To do this, you will need to use a multimeter. This device must be plugged into the network, and then measure the no-load voltage at the terminals. It should be several V more than that indicated on the structure. If there is no voltage, then it will be necessary to repair the charging unit. If there is no knowledge in the field of electronics, then it is recommended to purchase a new one.
If the battery is faulty, then you will need to disassemble the unit, inspect all the places where the wires are fastened and check their quality. If there are no damaged connections, you need to measure the voltage on all elements with a multimeter. The voltage should be 0.9-1 V or more. If there is a part with a lower voltage, then it will need to be replaced. The capacity and type of the element must necessarily correspond to the installed parts.
Diagram of the internal structure of the screwdriver.
If the charger and the rechargeable battery are in good working order, but the screwdriver does not work, then this device should be disassembled. Several wires go from the battery terminals, you need to take a multimeter and measure the voltage at the input of the button. If voltage is present, then you need to remove the battery, use the clamps to short-circuit the wires from the battery. The device should show a resistance value that tends to zero. In this case, the element is OK, the problem lies in the brushes or other parts. If the resistance is different, then the button will need to be replaced. To repair the button, in some cases, it is enough just to clean the contacts on the terminals with sandpaper.
In the same way, you will need to check the reverse element. Repair is carried out by cleaning the contacts.
If the electric motor operates at high speeds, and the speed cannot be adjusted, then the problem may be in the button or transistor that is used for adjustment.
The device of the gears of the screwdriver reducer.
If the chains to the engine are in good order, but the screwdriver does not work, then the problem is in the brushes. If these elements are worn out, they will need to be replaced.
The problem may be directly in the engine. To test the electric motor, you will need to disconnect the wires that are connected to the button. Next, using the same tool, you need to measure the resistance value at the wires fixing contacts. If the value tends to zero, then the winding has broken. In this case, you will need to rewind or install a new motor.
You will need to check the condition of the armature windings, since this element can be purchased and changed by yourself. To check the anchor, it will be necessary to measure the resistance on the adjacent collector plates, along the entire perimeter. The value should tend to zero.If, during the check, plates with a resistance that differs from zero are found, then it will be necessary to repair the armature or replace it.
Mechanical problems can be identified as follows:
In the process of work, the screwdriver makes extraneous sounds that were not there before.
The tool vibrates strongly during operation.
Fight of the chuck for the clamp.
The tool turns on, but it is not possible to use it due to jamming.
VIDEO
If during operation the device emits extraneous sounds, it means that the bushings or the bearing are worn out. To fix this, you will need to disassemble the electric motor, and then check the integrity of the bearing and the level of wear of the sleeve. The anchor should rotate freely, there should not be any friction or distortion. These devices can be bought at a construction supermarket and replaced by yourself.
The most common failures of the gear structure include the following:
shaft malfunction;
abrasion of the working base of the gears;
break of the pin on which the satellite is fixed.
VIDEO
In all cases, it will be necessary to replace the defective gearbox elements. All the above steps must be followed carefully. Disassembly of the screwdriver must be done in a clear sequence, otherwise any of the parts may be lost.
Video (click to play).
Anyone can repair a screwdriver, you just need to correctly identify the faulty element.
