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.
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The three main reasons that lead to the fact that you have to do the repair of a screwdriver with your own hands are:
Schematic diagram of a screwdriver.
Any screwdriver has the following main elements in its design:
Engine.
Reverse.
Reducer.
Speed controller.
A speed controller transistor that is connected to a heatsink.
Repair of the device most often has to be done due to the occurrence of various malfunctions that are typical for cheap devices and expensive ones. Among them stand out:
When a screwdriver breaks down, the main percentage of malfunctions is the battery.
Failed battery.
Broken power button.
Burnt anchor.
The presence of whistles and various squeaks during operation.
Reinforced tapping of the chuck.
The impossibility of regulating the speed of the screwdriver.
Screwdriver reverse does not switch.
The machine motor does not stop rotating after the screwdriver is turned off.
The device turns on for a fraction of a second, followed by wedging.
Consider the features of eliminating each of the listed faults.
In order to make sure that the battery of the screwdriver is broken, it must be checked with a multimeter.
The battery should first be checked before it can be replaced. The battery should be checked by the usual measurement of the voltage level using a multimeter at the terminals of the device. You can also check with any other tester. In this case, the output voltage of the batteries in working condition should be observed if they are charged. The values of 12V, 18V, etc., indicated on the battery cases, must be exactly observed. If this condition is not met, the device should be replaced.
Possible malfunctions of the screwdriver charger lead to the need to disassemble it and then check it using a tester that has already been used. Each battery included in the accumulator must be subjected to a similar test. After identifying the defective elements, you should buy special elements of the same type with the same capacity in the store in order to install them in the places of the previous ones, replacing the old ones with new ones.
When repairing the power button, you must have a special skill and relevant knowledge in the field of electronics. Disassembly of the apparatus should be carried out with the utmost care and caution. Otherwise, opening the device may cause parts of a certain type to easily fall out of the screwdriver.
It is best to first sketch the order of the different springs, contacts and screws.
After you have made sure that the cause of the breakdown is in the battery, it will need to be disassembled.
When the case of the device is opened, the device must be checked for the presence of contacts in it that have darkened. If there are any, it is necessary to clean them with sandpaper.
When the switch is already repaired, it is possible that the device will not regulate the number of revolutions if a smooth pull is made on its trigger. However, instrument functions are not lost when the trigger is fully pressed. In this case, the malfunction itself is associated with the adjustment circuit. In this case, a complete replacement of the switch is carried out.
If the device does not have a reverse, then it is replaced with a reverse switch, but you can try to repair it. To this end, the repair of the reverse resembles the repair of a switch button. The switch cover is carefully lifted up. Then the contacts are checked, cleaned and reassembled.
If burnt or deformed contacts are found under the cover, the reverse must be replaced. With the option of a button, when the reverse is assembled in its body, that is, inside it, the button changes completely.
In the event that when the button is lowered, the screwdriver motor continues to work, then the button will have to be changed.
When the button is lowered, the motor continues to rotate, which did not happen before, then the button changes completely. The reason for the continued rotation of the button may be its release, which was not observed before.This requires the button to be completely replaced, or it is necessary to replace the transistor separately.
You can check the speed controller using a multimeter set to the circuit ringing mode. The speed controller circuit is not included in the overall circuit, acting as a result of fully pressing the button. This is where the contact closure begins. Two wires are connected to the electric motor of the screwdriver, the same number goes to the battery button.
The power button is connected to the control element or field effect transistor through 3 wires, which is located outside the screwdriver housing. It is necessary to connect the probes in order to test the supply connected to the electric motor and to the wire that is the input.
If possible, the probes are connected not only to the motor wire of the device, but also attached to the reverse input contacts. The device can show whether there is a contact or not. Then, in a similar way, all measurements are carried out for another wire, which is the input. After that, you should move the reverse lever to repeat the measurements. If there are no contacts, then these changes affect the button.
The cause of the breakdown is also worth looking for in the brushes of the screwdriver motor.
If all the elements of the device are in good condition, which was shown by the operations that were carried out earlier, then it is imperative to check the condition of the motor brushes. This can be done by disconnecting the engine from the button by connecting a multimeter to its wires through the probes.
If there is no low resistance in the circuit, then this may indicate that the brushes are worn out. This does not exclude the breakage of the anchor, which can occur in rare cases. Winding breaks may also occur. In this case, a complete replacement of the engine is performed. If only the brushes are worn out, then you can restore the screwdriver motor with your own hands.
To restore engines, for some models of screwdrivers, only the brushes are changed, and the element is not completely disassembled. To repair other models, the rear cover of the engine is separated with brushes from its body. For this purpose, the rolling of the cover is bent without touching its edges, because they must be returned to their original place after the assembly is completed.
Brushes with flexible wire are connected on the basis of a spot welding method for attachment to the holder. It is possible to solder wires for new brushes. For this purpose, you can use only refractory solder.
Bearings can wear out or become clogged when working with a screwdriver for a long time.
Before starting the assembly of the electric motor of the screwdriver, with the help of a thin wire, which serves as a clamp, each brush is retracted in the brush holder, the cover is installed in its original place. At the same time, the brushes release and go around the case along the edges, which contributes to the best pressing of the back cover.
If the screwdriver works for a long time, then this may be accompanied by a process of curvature of the shaft related to the gearbox due to heavy loads and pressure on the tool. The cartridge, screwing onto the shaft, sometimes causes a strong beating during operation of the device. The support sleeve or shaft bearing can be severely worn. As a result of damage to the bushing or only the bearing, and not the shaft, only they are replaced.
Sometimes the engine cannot be started for a certain fraction of a second, that is, it stops abruptly. This could be caused by a gearbox failure. Often a malfunction occurs due to a broken pin that serves as a fastener to the satellite. It is possible to replace the carrier or the entire gearbox, which can fail if the gear teeth are worn out.
If, after carrying out all the above operations, no malfunctions were found in the device, then it is necessary to check the condition of the armature and the serviceability of the motor brushes. In this case, the engine should be disconnected from the switch button, and then measure the resistance by connecting a tester of any kind to the engine wires. If there is no resistance in the circuit, then this may indicate that the brushes are worn out.In this case, malfunctions in the motor armature are not excluded, which may be due to a winding break. However, these types of failures may be rare.
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Video (click to play).
If the motor armature is completely burned out, then the motor of the device is subjected to a complete replacement. If only the motor brushes are worn out, it is better to repair the device yourself. Before starting repairs, gently open the screwdriver motor housing so as not to damage its edges. All stages of work related to the replacement of brushes are indicated above. It is possible that the armature bushings were worn out due to the magnet, which came off and began to come into contact with the anchor. By dropping a drop of special oil on the bushing, you should turn off the engine to wait until the oil has spread to all bushings. However, it still requires replacement over time.
