Signs of a malfunctioning mechanical part of a screwdriver may include the following:
The reasons for "extraneous" sounds during the operation of the tool may be wear of the bushings or armature bearing. To do this, it is necessary to disassemble the electric motor and examine it for the integrity of the bearing and the degree of wear of the sleeve. The anchor should rotate easily, without friction and distortion. If necessary, these elements can be purchased at the store and replaced by yourself.
In all cases, it is necessary to replace the defective parts of the gearbox. All the described actions require attention and consistency in disassembling and assembling the screwdriver. Having shown these qualities, you will be able to independently repair the Interskol screwdriver with your own hands, or any other, and only in some cases resort to the help of a service center.
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A screwdriver is a tool often used in the professional field for repair and construction work, as well as in everyday life. Like any electromechanical device, screwdrivers are prone to malfunction. This device is not a complex device, and in the event of a problem, you can repair the main malfunctions of a screwdriver with your own hands.
The figure below shows the internal structure of the battery device.
In screwdrivers, both collector electric motors and brushless motors (they do not have electric brushes) can be installed.
If your screwdriver is broken, then the malfunctions of this device may be as follows.
All malfunctions, except for the electrical plug, can only be eliminated after disassembling the device.
To disassemble the device, follow these steps:
disconnect the battery pack from the body of the device;
unscrew all fasteners holding the 2 halves of the device together;
remove the upper part of the case;
remove all contents from the body of the device;
carefully disconnect the start button from the housing without damaging the wires connecting it to the engine;
remove the speed switch;
disconnect the motor, gearbox, coupling and cartridge by unscrewing 4 screws;
To unscrew the cartridge, you need unscrew the screw , which can be seen inside the mechanism with the cams open. Unscrew the screw clockwise, since it has a left-hand thread. After that, the chuck must be unscrewed from the gearbox shaft by turning it to the left (right-hand thread).
If you have a battery-powered device, then the first step is to check the batteries in the battery pack by disassembling it. There are collapsible and non-collapsible blocks. In the second case, you will need to carefully insert a screwdriver into the place where the walls of the block are glued together and, slowly, separate them.
Next, it is necessary measure voltage on all banks. The voltage rating is indicated on the case of each battery. The voltage should be slightly lower than the specified, but the same on serviceable batteries. Faulty batteries will differ significantly from the rest in terms of voltage output - they will need to be replaced. New batteries can be purchased online.
It is important to solder them correctly, that is, in series: the plus of one battery is connected to the minus of the other, and the plus of the second to the minus of the next, etc.
If you are the owner corded screwdriver , then the verification algorithm is somewhat different. First, you need to unwind the body of the device and remove one half of it. Take the tester and “ring” the power cord for a break. In the case of a working cord, you need to check the start button. Check with the button pressed if there is a circuit on its output contacts. If the button is defective, it will need to be replaced or repaired. How to do this will be discussed next. With a working button, the problem may lie in the electric brushes or the motor.
Below is a wiring diagram of a cordless screwdriver.
It can be seen from the diagram that 2 wires from the battery fit on the button, and 2 wires go to the engine from it. Also, 3 wires from the transistor responsible for speed control are connected to the button. To understand the device of the screwdriver button, it must be disassembled. All wires going to this part can not be soldered. They will not interfere with disassembly.
Remove push mechanism (red) from your seat. Do this with gentle twisting motions while pulling the part in the opposite direction of the button, making sure that the jokes do not break.
Next, remove button cover . In the places indicated by the arrows in the figure, use a knife and a screwdriver to pry and push out the latches, and then remove the cover.
When you remove the cover, you will see reverse compartment . But the button mechanism will still be unavailable. Using a soldering iron, separate the 2 elements (indicated by an arrow in the following figure).
Carefully pull out element number 1, then remove the cover that closes the compartment with the mechanism for turning on the device.
While holding the return spring, remove the mechanism from the housing.
In a faulty button, you will see erased contact pads.
contact pads wear out quickly due to the poor quality of the metal. Fine metal dust from worn contacts accumulates between them and closes the pads. As a result, spontaneous start of the device occurs.
Use cotton wool soaked in alcohol to remove metal dust. If this fails, you can scrape it off with a knife. After these steps, the spontaneous start of the device will stop.
If the speed controller does not work, then the transistor has burned out, which must be replaced.
To check the condition of the brushes, disassemble the engine , by bending the “antennae” located at the end of the case.
Next, with light hammer blows on the motor shaft, knock the rotor out of the housing.
In this case, the cover in which the electric brushes are located will first be removed.
The next photo shows that the collector has black color . This means that it will be contaminated with dust from the brushes. As a result of contamination of the collector, as well as the grooves between its plates, the engine power drops and the brushes spark. It is necessary to wipe the collector with cotton soaked in alcohol and clean the grooves with a needle.
The following photo shows what a clean collector looks like.
If the brushes are worn out, they will need to be replaced. For some models of screwdrivers it is difficult to find on sale original brushes . But you can find brushes that are the right size, then trim them on the grinder and connect (solder) to the brush holders.
Sometimes, to replace the brushes, you will need to cut a groove into them. It depends on how they are attached.
To better understand how the brushes are replaced, you can use the following video.
The motor brake is a device that stops the rotation of the armature when the start button is released. In screwdrivers, this function is implemented by closing the plus and minus of the motor when the button is released.As a result, there is a large self-induction, and there is spindle lock (with a lot of sparking from under the brushes). If the engine braking does not work, then the control transistor or start button will need to be replaced.
Mechanical failures of a screwdriver include malfunctions of the ratchet, gearbox and chuck of the apparatus.
If the ratchet on the screwdriver does not work, then you will need to disconnect it from the gearbox for troubleshooting. Sometimes special rods are installed in the coupling, which regulate the force, and in some devices, instead of rods, 2 balls are installed in each hole. They are pressed by a spring, which, when the adjusting ring is twisted, presses on the balls.
In most cases, the repair of a screwdriver ratchet consists in cleaning its components from contamination and applying new lubricant.
If unusual noises are heard in the gearbox, or the rotation of the spindle is jerky, with slippage, then the cause may be the failed gears of the mechanism, worn teeth on its body.
Gears most often break if they are made of plastic (used in cheap devices). If this happens, then they must be replaced.
In the next photo you can see the gear unit.
The reason that the spindle does not rotate when the engine is running may be the wear of the plastic teeth inside the gearbox housing.
To restore the mechanism to working capacity, it is necessary to disassemble the gearbox (it is better to photograph the disassembly process) and screw in place of the worn teeth small bolt , ground down to the required size. The place where you will install the bolt must be punched. It should be strictly opposite the plastic tooth located on the inside of the case.
Make such markings on the back of the case, opposite the first.
Next, drill holes in the marked places.
Screw the bolts of the required length into these holes, after grinding them so that they are flush with the other plastic teeth. After adjusting the bolts, the gearbox can be assembled with the required amount of lubricant applied to the gears. On this, the repair of the screwdriver gearbox can be considered complete.
To start repairing this unit, you must first remove the chuck from the screwdriver . To do this, complete disassembly of the screwdriver is not required. How to unscrew the keyless chuck was described above.
Common chuck malfunctions include incomplete exit of one of the cams, as shown in the following photo.
The cause of the malfunction may be worked thread on the nut clamping the cams, or worn teeth on the cams themselves. To verify this, you will need to disassemble the cartridge.
Disassembly and repair of the screwdriver chuck is done as follows.
It is necessary to hit with a hammer on the part protruding in its center. In order not to deform this part, you can lay a small piece of wood.
Separating the upper part will not be enough, and further disassembly of the cartridge will be required. To do this, lightly clamp the bolt into the cams and hit it with a hammer.
When the inner part of the cartridge falls out, its analysis is considered complete. You will see nut consisting of 2 halves . Most often, malfunctions in the cartridge occur due to this part. The thread on it wears out and the cams slip when twisting. Therefore, there is an incorrect centering of the latter.
Also, the thread can be worked on the cams, which, like the nut, must be replaced. But if you do not find the necessary parts to change them, then you will need complete cartridge replacement . When assembling the cartridge, the cams must be installed at the same level, in a compressed state, after which a nut consisting of 2 halves is put on, and after that the whole structure is placed in the body.When the problem is fixed, you can assemble the screwdriver.
In practice, finding spare parts for a cartridge is troublesome. It is easier to buy a new chuck, since its price is not so high, within 300 rubles.
VIDEO
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.
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.
VIDEO
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.
VIDEO
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.
- the screwdriver does not turn on;
Read about the device of a screwdriver in the article Device of a screwdriver.
Some spare parts (motor, reducer, switch, etc.) for the most popular models can be bought here (only it is better to buy through an online store, because the price may be higher in a regular store of this network).
The screwdriver may not turn on for three main reasons: the battery is faulty (not charged), the power button is faulty, the motor brushes are worn out, or the anchor itself has burned out (very rarely).
Battery . Checking the battery is carried out by simply measuring the constant voltage at its terminals with any tester. The output voltage of a working charged battery must correspond to that indicated on the case - 12V, 18V, etc. Otherwise, the battery must be replaced. The screwdriver charger may also be faulty.
Speed controller and reverse . The screwdriver speed controller is checked with a multimeter in the continuity mode. It should be noted that if the button is fully pressed, the contacts close in it and the voltage to the engine (to reverse) is supplied directly, excluding the speed controller circuit. Two wires from the battery come to the button, after it two wires are connected to the engine through the reverse contacts. The power button can still have three wires for connecting a regulatory element (field effect transistor), which is placed outside the case. For continuity, the probes are connected to the input and one of the motor wires (if possible, to the reverse input contacts) alternately, then the button is pressed all the way. The device indicates the presence or absence of contact, after which the second input wire is measured. We translate the reverse lever and repeat the measurements. If there is no contact, the button changes.
Repairing a screwdriver button with your own hands is possible, but only if you have certain skills. It is important to understand that after opening the case, many switching parts will simply fall out of the case. This can be prevented only by gently lifting the cover initially and by the desired sketching of the location of the contacts and springs. If darkened contacts are found, they are cleaned with sandpaper. After assembly, repeated measurements are taken and with positive results (there is contact), the button is installed in its original place.
It should be noted right away that if, after repairing the button, the screwdriver motor started working when the button was pressed completely, and when the button was pressed smoothly, the speed was not adjusted, then the reason should be sought in the adjustment circuit. Most screwdriver repairs in this case come down to replacing the entire button.
If there is no reverse, replace the reverse switch or try to repair it. To do this, open the cover of the switch and, as in the case of the button, gently lift it. We check the contacts, clean and assemble. If the contacts are burned or deformed, the reverse must be replaced. There are options for buttons in which the reverse is assembled inside the button body, in this case the button changes entirely.
If, when the button is released, the engine continues to spin, and before it did not spin, in this case it is necessary to pay attention to the speed controller, namely the control transistor. Either the entire button or the transistor should be replaced.
electric motor . If all of the above operations showed the health of the elements, then it is necessary to check the condition of the motor brushes. To do this, the engine is disconnected from the button, and the multimeter probes are connected to the engine wires. The absence of low resistance in the circuit indicates brush wear, but armature breakage (winding breakage) should not be ruled out, although this happens very rarely. Usually, in this case, the entire motor changes, but if the brushes are worn out, it is possible to restore the screwdriver motor on its own. On some motors, the brushes can be replaced without dismantling the motor. For others, it is necessary to separate the rear motor cover with brushes from the motor housing.
To do this, it is necessary to bend the rolling of the cover, but in such a way that the edges do not break off, since they will need to be returned to their place after assembly. The flexible wire of the brushes is connected to the holder using spot welding, but the wires of the new brushes can also be soldered, but only with refractory solder, for example, POS-60. Before assembling the engine, the brushes are removed in the brush holder with a thin wire clamp, the cover is put in place and the wires are pulled out, thereby freeing the brushes. Next, go around the edges of the case to firmly press the back cover.
Extraneous whistles and squeaks during the operation of a screwdriver can be caused by wear on the armature bushings or a detached magnet that is in contact with the anchor. In the first case, you can extend the life of the engine if you put a drop of precision oil on the bushings, and then turn on the engine so that the oil disperses into the bushings themselves. In this way, you can only extend the life of the engine, but over time you still have to replace it.
Reducer . From the long operation of the screwdriver under heavy loads and when pressed sideways, the gearbox shaft is bent, on which the cartridge is screwed on, there is a strong beating during the operation of the screwdriver. The support sleeve or bearing of this shaft may also wear out. If only the bushing or bearing is damaged, and the shaft is not bent, then you can try to replace only worn parts.
Video (click to play).
It may happen that the engine starts for a fraction of a second and stops abruptly. Everything points to a breakdown in the gearbox, usually it is a breakdown of the pin on which the satellite is attached. You can try to replace the carrier or the entire gearbox. The failure of the gearbox is often due to wear of the gear teeth. Read a detailed description of the screwdriver gearbox device here.
