Do-it-yourself dewalt screwdriver repair

In detail: do-it-yourself dewalt screwdriver repair from a real master for the site my.housecope.com.

One of the most popular tools for home craftsmen is a screwdriver. However, this device sometimes breaks down, like any other. If this happens, in some cases you can replace this tool with an electric drill. If the work cannot be done with an electric drill, you will need to take the screwdriver to a service center so that specialists can repair the tool. However, this can take a lot of time and money. Therefore, you can use another option - to repair a screwdriver with your own hands.

Screwdrivers are commonly used for furniture assembly both at home and in production.

Before carrying out repairs, you will need to familiarize yourself with the design of this device. On fig. 1 you can see this tool in disassembled form.

Elements that are needed in order to make a screwdriver:

multimeter;
clamps;
sandpaper;
spare items.

Figure 1. Screwdriver device.

The main element is the start button, which performs several functions: turning on the power supply circuit of the electric motor and the speed controller. If you press the button all the way, the motor power circuit will be closed by contacts, as a result of which maximum power will be provided. The number of revolutions in this case will also be the maximum possible. The device has an electronic regulator, which consists of a PWM generator. This element is located on the board. The contact, which is placed on the button, will move along the board depending on the pressure on the button. The level of the adjustable pulse 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 stronger the master presses the button, the greater the value of the pulse on the transistor will be and the more it will open and increase the voltage on the electric motor.

Video (click to play).

The rotation of the motor will be reversed by changing the polarity at the terminals. This process is carried out using contacts that will be thrown by the master using a reverse handle.

Charger for cordless screwdriver.

In screwdrivers, in most cases, single-phase continuous current collector motors are installed. They are reliable, easy to manufacture and maintain. An ordinary screwdriver consists of the following elements:

The geared design will convert the high RPM of the electric motor shaft to the lower RPM 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;
carrier.

The sun gear is powered by the armature shaft, its teeth actuate the satellites that rotate the planet carrier.

A special regulator is used in order 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:

screwdriver does not turn on;
it is impossible to switch the reverse mode;
it is impossible to adjust the number of revolutions.

Scheme of the device of the gearbox of a cordless screwdriver.

The first step is to check the battery of the screwdriver.If the tool was put on charge, but this did not help, then you will need to prepare a multimeter and try to find a 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 undervoltage, then it will be necessary to identify the faulty element: a battery or a charger. To do this, you need to use a multimeter. This device must be connected to the network, and then measure the voltage at idle at the terminals. It should be a few V more than what is indicated on the design. If there is no voltage, then you will need to repair the charging unit. If there is no knowledge in the field of electronics, 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 0.9-1V 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.

Scheme of the internal device of a screwdriver.

If the charger and battery are working, but the screwdriver does not work, then this device should be disassembled. There are several wires coming 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 the wires from the battery. The device should show a resistance value that tends to zero. In this case, the element is working, the problem lies in the brushes or other details. 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 runs at high speeds, while the speed cannot be adjusted, then the problem may be in the button or the transistor that is used to adjust.

The device of the gears of the screwdriver gearbox.

If the chains to the engine are working, 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 could be in the engine itself. 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 wire fixing contacts. If the value tends to zero, then the winding is broken. In this case, you will need to rewind or install a new electric 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 adjacent collector plates, around the entire perimeter. The value should tend to zero. If, during the verification process, plates with a resistance that differs from zero are found, then the armature will need to be repaired or replaced.

Mechanical problems can be defined as follows:

During operation, the screwdriver makes extraneous sounds that were not there before.
The tool vibrates strongly during operation.
The fight of the cartridge for the clamp.
The tool turns on, but cannot be used due to jamming.

If during operation the device makes extraneous sounds, this 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 wear level of the bushing.The anchor should scroll freely, there should be no friction or distortion. These devices can be bought at a building supermarket and replaced by yourself.

The most common gearbox failures include the following:

shaft failure;
abrasion of the working base by gears;
a break in the pin on which the satellite is fixed.

In all cases, it will be necessary to replace the defective elements of the gearbox. All of the above steps must be followed carefully. The screwdriver must be disassembled in a clear sequence, otherwise any of the parts may be lost.Anyone can repair a screwdriver, you just need to correctly identify the faulty element.Hello everyone! I practice a little repair of various kinds of equipment no larger than a TV.This time, a familiar carpenter-builder turned to me with such a beast, the complaint did not work, upon detailed examination it became clear that nothing was clear. Shurik simply did not respond to pressing the button. After the voltage was measured on the battery, the cartoon showed 20.5V, which corresponds to a fully charged battery. The question is what is the problem? Or Shurik or fools akb. I contacted the owner again and clarified that Shurik was definitely in good order and was working normally with another battery, well, let's open the battery.We see inside 5 cans of the 18650 type, each bank, when fully charged, produces 4.1V * 5 = 20.5VSo all the banks are fully charged and the problem is different. When parsing, I noticed that there are additional contacts on the battery terminals except + and -. There are also two additional contacts on the screwdriver contacts. contact in the battery itself there is a board (most likely a battery charge balancing board)After a visual inspection of the board, I was confused by one darkened resistor under position R1, it is not enough to check its capabilities and there is a great chance to make a good firework with cartoon probes, banks of this type can give up to 30A.Unsolder all contacts and remove the boardWe call the resistor, judging by the scheme, its nominal value should be 10 ohms. In fact, the cartoon showed 170 kOhm. When soldering, the resistor fell apart in half. I found the same smd resistor soldered into place, reassembled in reverse order and a miracle happened. Apparently, the feedback with the screwdriver was broken and he did not see the battery itself. I can’t add a video yet, only a link to a working Shurik) otherwise they won’t believeA screwdriver can be safely classified as a tool that quite often has to be used not only in everyday life, but also for working on construction sites. But, like any complex technical accessory, the product can break. How to repair a screwdriver yourself, we will consider in this text. Image - Do-it-yourself dewalt screwdriver repair

Equipment in the construction market, where screwdrivers occupy a separate place, is quite large. Many models have individual criteria, are characterized by assembly quality and cost. However, most models are characterized by the basic principles of operation and internal design.

The basic elements of any screwdriver include:

the presence of an electric motor;
planetary reductor;
adjustable functional button "Start";
reverse switch;
effort regulator;
power unit.

The electric motor is powered by a DC network, structurally represented by a cylindrical shape. Inside is an anchor with brushes and magnets. A feature of the electrical circuit of the motor suggests that the direction of the supply voltage flow will be directed to the brushes. When the supplied polarity is reversed, the motor reverses.

The planetary gearbox is an important element capable of converting the high-frequency vibrations of the electric motor shaft into low-frequency revolutions of the cartridge shaft. As a rule, these parts are made of 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 it is possible to drill in a wood, plastic base or metal.

The "Start" key starts the device. It is able to control the number of revolutions, providing the ability to choose the optimal rotation speed for the cartridge shaft. Accordingly, a strong pressure will drive the engine at high speeds, and with a decrease in pressure, the power criterion will weaken.

The reverse switch is necessary for carrying 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. The current models provide a 16-step adjustable gradation, which allows you to determine with maximum accuracy and convenience what puff speed is relevant when working with different materials.

The screwdriver is powered by batteries of overall size, where the power of the supply voltage (depending on the model device) can range from 9 to 18V.

If at some point you find that your screwdriver does not turn on, then most likely it has some kind of malfunction. Practical experience shows that the inoperability of the tool can be observed for two reasons:

the breakdown is related to the electronics of the device;
failure may be mechanical.

Understanding the objective causes of electrical breakdown, we can note its characteristic features:

the product stops responding to switching on;
the device has ceased to regulate speed;
reverse operation has 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 worn out or a bearing has collapsed. Often this happens on a hammer instrument.

For example, if the tool stops turning on, then initially you need to check the health of the battery. If the breakdown does not disappear when the device is based on charging, 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 case of the device and compare it with the measurements on the battery. The data should roughly match. If the voltage is too low, then most likely the problem lies in the charger or battery pack.For example, the charger can be checked with a multimeter by plugging it into the network and taking measurements at the terminals of the device at idle. It is important that the voltage criterion be somewhat higher than the nominal one. In a situation where there is no voltage, then, unambiguously, the culprit of the breakdown is the charging unit. Screwdrivers of the company Interskol "get sick" with this rather frequent problem. In general, to fix the defect, you will need specific knowledge in electronics or you will need to purchase a new unit.If you find a battery problem, for example, with a Makita screwdriver, you can open this block with your own hands, where the power elements are located. As a result of the opening, it is necessary to examine the connecting wires and make sure that the soldering is of high quality. If no visible defects are found, then using a scanner, voltage measurements in each element should be made. The values should show 0.9 - 1V voltage power. If a block with a low voltage indicator is found in a row, then it must be replaced.

When everything is in order with the battery and charging goes without problems, but the tool refuses to activate, it will check the operation of the device button.To do this, you will have to disassemble the device and on its terminals coming from the button, you should measure the voltage with a multimeter, which is supplied at the input of the button. It is necessary to carry out the operation with an active battery. If the signal is on, then the battery must be removed and its contacts shorted using clamps. On the multimeter, you need to switch to ohm mode. The screwdriver button is clamped all the way and measures the output voltage. If the value of the resistance readings on the device tends to zero, then the button is working properly. And this means that the problem should be looked for in brushes or other motor modules. If a break in the signal is detected, it is recommended to repair the button, thereby returning the screwdriver to the working system of tools.

Quite often, problems with buttons are associated with poor contact at the terminals. You can simply clean the contacts with sandpaper and the problem will be solved. The main thing is that in the process of disassembling and assembling the device, do everything carefully, without losing parts.

Gearbox failure refers to one of the mechanical problems with a screwdriver. Some of the most common reduction block problems include:

physical curvature of the axis of the reduction shaft;
a clear defect in the working surface of the gears;
failure of the shaft support sleeve or the 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.

Lithium batteries are increasingly being used in everyday life. Currently, they are increasingly found as replacement batteries for screwdrivers and other power tools. Despite their advantages, lithium batteries are also not without drawbacks.So, after 1.5 years of operation, the batteries from the DeWalt screwdriver began to discharge quickly, it became impossible to work. Batteries were charged to a maximum of 14.4 volts, although a standard DCB-107 charger was used for this. In addition, charging took place very quickly, instead of the prescribed 60 minutes, at most 15 minutes.Before talking about how we managed to solve this problem, I would like to introduce the reader to the device of a lithium battery from a screwdriver.This is what a standard DeWalt DCB-145 battery looks like.To open such a battery, you will need a TORX hex screwdriver. The battery consists of 4 lithium (Li-ion) “cans” SAMSUNG SDI INR18650-13B capacity 1300 mA/h each. All four "cans" are installed in a plastic box and connected in series using current-carrying plates. The plates are welded to the battery contacts by spot welding. It appears to be a high quality factory assembly.I do not advise you to separate the “banks” of a composite battery by biting the connecting current-carrying plates. I did so and regretted it. Next, I will tell you why you should not do this.The batteries themselves SAMSUNG SDI INR18650-13B do not have a built-in charge / discharge controller. Unfortunately, to find documentation for batteries of this particular model (with the index 13B) I did not succeed. But, judging by the parameters of the batteries of this line, the maximum continuous discharge current (Max Continuous Discharge Current) can be from 18 (INR18650-13L) up to 23 (INR18650-13M) ampere! Not surprisingly, they do not have a built-in controller.Also in the battery case is a 5-pin connector and a small printed circuit board.A multi-pin connector is required so that when charging it is possible to control the charge of each of the four INR18650-13B batteries separately. As you know, the voltage is more than 4.14.2V for lithium batteries is dangerous and may cause damage or even fire.Therefore, the charger equalizes (balances) the current through each “bank” of the composite battery so that the voltage on each of them does not exceed 4.1V.Also on the printed circuit board is a temperature sensor that is adjacent to one of the lithium “cans”.Thanks to the sensor, the standard DeWalt DCB-107 charger measures the temperature of the battery and turns off the charge mode if the battery is overheated or has a temperature below +4 0 C. In addition to the temperature sensor, some circuit is mounted on the board, but it is filled with sealant.

This battery assembly is called “Pack for Power Tool“, i.e. “Package” or battery assembly for power tools. This is how she looks.Large companies like Samsung supply such assemblies to custom power tool manufacturers. Perhaps that is why I could not find the exact specifications for INR18650-13B batteries.We got acquainted with the Li-ion battery device for power tools. Let's get back to our "dead" batteries.Before the batteries “died”, they were very discharged. We used a screwdriver until the battery was dead, and then, after taking a break, we worked with it for some more time. After that, the batteries began to charge poorly and did not hold the capacity.After measuring the voltage on each “bank” of the battery, it turned out that 3 out of 4 “banks” were not fully charged - up to 3.5 volts. Only one charged to the required 4.1 volts (for Li-ion).If we add up the voltage of all the cans, we get exactly the same 14.4V. Let me remind you that the standard charger charged the battery very quickly and turned off.The first thing that came to mind was to replace those lithium “banks” that were not fully charged. But, the search for the original INR18650-13B did not return any results. Perhaps due to the fact that such assemblies are supplied only on order and are not available at retail. And the cost of four new batteries, for example, INR18650-22R almost equaled the price of one battery DeWalt DCB-145. Therefore, I decided to refuse to replace the batteries at that time.And then a sensible thought came to mind, and as always, it is late. What if the factory charger failed to properly balance the composite lithium battery after a deep discharge? That is, the regular DeVolt’s charger charged one “can” to the required 4.1V and turned off. At the same time, the remaining 3 lithium “banks” were not fully charged, but only up to 3.5V.It was decided to check the standard DCB-107 charger for any kind of malfunction, but it turned out to be working. Yes, and new batteries charging charged perfectly.Thus, I came to the conclusion that the stock charger was unable to properly balance the composite lithium battery after a deep discharge.It was decided to discharge / charge each 18650 lithium cell separately using a third-party charger. This was done using a charger. Turnigy Accucell 6 (similar to IMAX B6), which I have already talked about.I discharged each bank of 18650 to 3V with a current of 0.3A. Then I charged up to 4.1V with a current of 0.5A. Then he discharged again in order to determine how much current is poured into each particular “jar”. This is necessary in order to evaluate their capacity. As it turned out, the batteries were in good order and each of them was “filled” with 1164 before 1186 mA. Which is not so far from the declared capacity of 1300 mA / h. Thus, I was convinced that the batteries are in good condition, and it is not worth replacing them.After the test (charge-discharge) of each battery, we measure the voltage on each lithium “bank”. It should be within 3.13.3V on each. Thus, the composite battery will discharged up to 12.4Then I collected all the "banks" in the box, soldered the board with the connector and installed it in the case. Delivered completely discharged the DeWalt DCB-145 battery is already in the regular DeValt charging and has detected the time of the start of the charging process.As I expected, after 1 hour (60 minutes, as indicated in the instructions), the charge was completed.As a “control shot”, I measured the voltage at the terminals B+ and B-. It amounted to 16.4Vas expected for a fully charged battery.Thus, it was possible to restore two DeWalt DCB-145 batteries and avoid wasting money on buying new batteries, the total cost of which is almost equal to the cost of an inexpensive screwdriver.Now I’ll tell you about the “rake” that I stepped on.Attention! The assembly must be done very carefully and avoid short circuits between the terminals of the “cans” and those terminals that go to the balancing connector. If you close something with pliers or tweezers, then fireworks from sparks are guaranteed! I have seen this in practice. The currents are such that a wire with a cross section of 0.5 mm. melt as if it were the thinnest fuse wire.I also categorically do not advise separating lithium cans by cutting or biting the connecting current-carrying plates that are welded by welding.First, it's not necessary. You can charge each “bank” simply by connecting the terminals of the charger to the poles of the desired battery. The only thing that may be required is to unsolder the pins of the balancing connector and temporarily remove the connector itself from the assembly.Secondly, it is possible to damage the insulation of lithium batteries and short them out because of this.Thirdly, after the lithium “banks” have been tested, the question of connecting them together will arise. And even if the plates can be soldered together, then putting such an assembly back into the case will be a very time-consuming task. The battery case is very tightly fitted to the dimensions of the assembly.Furniture repair or installation 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 components, among which the following can be distinguished: a gearbox, a reversing device, an electric motor, a speed controller, and if the tool is autonomous - a battery (charging battery battery).Moreover, both expensive and cheaper screwdrivers basically have a similar device, which differs from each other in the presence of certain advanced options. From here, we can highlight the main reasons why a 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 serviceability of the battery or the breakdown of the electrical cable from the mains (mains screwdriver).

Failure of the start button of the tool.

Engine speed not regulated or poorly regulated.

The impossibility of reverse switching.

Chuck runout.

The electric motor does not rotate.

Everyone understands that, regardless of the "steepness" of the perforator, without an energy source, its operation is impossible. Therefore, first of all, you need to check the health of the battery if your rotary hammer is mobile and does not depend on the power source. The main reason for the inoperability of the battery is its discharge or long-term operation. The second reason is eliminated by a complete replacement of the battery, and the first by simple recharging using the rectifier that comes with the sale of the tool. Image - Do-it-yourself dewalt screwdriver repair

Screwdriver battery disassembled

As a rule, two batteries are included in the same kit: one is in use, that is, in operation, and the other is being recharged. In the event of a charger failure, it would 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 corded screwdriver, first of all, if the engine is not rotating, 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 (the contacts burn), the cable plug may fail to work for the same reasons, and the cable itself may 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 has to be used, 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) screwdriver

It is not difficult to get to the failed start button: you need to unscrew all the screws connecting the two halves of the tool body with a Phillips screwdriver. Next, using an electric soldering iron, disconnect the button wires from the electric motor, disconnect the terminals connecting the button to the battery or mains power cable and remove the problem from the case. We insert a new button in its place, do the connection process in reverse order and check the operation of the new part by connecting it to the battery or power cable.

Steps for disassembling the screwdriver button

Sometimes it is impossible to purchase a new start button in stores 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, do-it-yourself repair of the start button 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 produce high-quality work. The regulator is located in close proximity to the start button or is made as one piece with it, however, the speed regulator transistor is attached to the electric motor where it is cooled through the radiator grilles.

Location of the motor speed controller (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. Luckily they are available and are relatively inexpensive. All attempts to repair it led to the same conclusion, unless, of course, you are an electrical engineer.

The screwdriver's reversing switch plays an important role in the work of screwing in self-tapping screws, as well as their extraction in cases of need. The electric motor reverse circuit is located in the same housing as the speed controller, and the speed redirection switch button itself is located in a convenient place on the handle.

Start and reverse button side by side

Switching is carried out by changing the polarity on the terminals by moving the reverse button. Repair of the entire reverse circuit, including a PWM generator located on the board, comes down to cleaning the switch contacts and replacing the reverse circuit with a new one.

The beating of the screwdriver chuck indicates that there are problems in the health of the tool gearbox, which is located immediately behind the electric motor. This is another reason why a full blown screwdriver does not work.

Details of the planetary gearbox of the screwdriver

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) the curvature of the gearbox shaft;
b) wear of the gears of the reducer;
c) failure of the thrust bearing of the gearbox shaft;
d) maximum wear of the pins on which the satellites of the planetary gear are mounted.

All of the above parts are of factory origin and are not subject to this repair. The problem of the beating of the screwdriver chuck in this case is solved by replacing the gearbox parts with new ones.

Malfunctions of the electric motor of a screwdriver are not much different from similar problems of a grinder, drill and other power tools.The first thing that can be the reason why the screwdriver does not work is the wear of the motor brushes, which can be easily replaced with new ones that are not very expensive. The second reason is the failure of the armature winding or motor stator.

The appearance of the electric motor of the screwdriver

Most often, an interturn 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, let it “rest”.

By the way, overheating of the screwdriver can lead to leakage of lubricant from the gearbox, which will lead to the failure of its main parts, which were mentioned above.

Another problem can be observed in the armature of the electric motor: pollution or oiling of the collector, which transmits electricity to the motor from the brushes.

Screwdriver motor brushes and commutator

The collector can be repaired at home by washing and cleaning it with fine sandpaper. But the stator and armature windings will have to be restored in a specialized workshop or the engine will be completely replaced with a new one.

In conclusion, I would like to note that a screwdriver will work for a long time and with high quality if it is treated with care, without showing "fanaticism" during its operation.