How to Change Brushes On a Bosch Screwdriver
The three main reasons that lead to the fact that you have to do the repair of a screwdriver with your own hands are:
- If the battery is defective or not charged.
- The power button does not function.
- The motor shields were worn out or the anchor burned out.
The scheme of the screwdriver.
Any screwdriver in its design has the following main elements:
- Speed control.
- The speed regulator transistor that is connected to the radiator.
Causes of a screwdriver malfunction
Repair of the device most often has to be done in connection with the occurrence of various malfunctions that are characteristic of cheap devices and expensive. Among them stand out:
When a screwdriver breaks down, the main percentage of faults is the battery.
- Broken battery.
- Broken button to turn on the device.
- Burnt anchor.
- The presence of whistles and various creaks during work.
- Reinforced tapping of the chuck.
- The inability to control the speed of the screwdriver.
- The reverse of the screwdriver does not occur.
- The engine of the device does not stop turning after the screwdriver is turned off.
- The device turns on for a split second, followed by wedging.
Consider the features of eliminating each of these malfunctions.
In order to verify that the screwdriver’s battery 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 verify using any other tester. In this case, there should be a coincidence of the output voltage of the batteries in working condition, if they are charged. The values indicated on the battery housings 12V, 18V, etc., must be strictly observed. If this condition is not met, then the device should be replaced.
When repairing the power button, you must have a special skill and relevant knowledge in the field of electronics. Dismantling the device should be carried out with utmost care and caution. Otherwise, opening the device may cause parts of a certain type to fall out of the screwdriver with ease.
It is best to pre-draw a sketch of the arrangement of different springs, contacts and screws.
After you make 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 that have darkened. If available, it is necessary to clean them with sandpaper.
When the switch has already been repaired, it is possible that the device will not adjust the speed if a smooth pull is made on its trigger. However, the functions of the device are not lost when the trigger is fully pulled. In this case, the fault itself is associated with the adjustment circuit. In this case, the circuit breaker is completely replaced.
If the device does not have a reverse, then it is replaced by a reverse switch, but you can try to repair it. To this end, reverse repair is reminiscent of a switch button repair. The switch cover gently lifts. Then the contacts are checked, cleaned and assembled.
If burnt or deformed contacts are found under the cover, the reverse must be replaced. With the button option, when the reverse is assembled in its body, that is, inside it, the button changes completely.
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Instrument Engine Diagnostics
In the event that, when lowering the button, the screwdriver motor continues to work, then the button will have to be changed.
When the engine continues to rotate when the button is lowered, which has not happened before, then the button changes completely. The reason for the continuation of the rotation of the button may be its release, which was not observed before. This requires a change of the button completely, or it is necessary to replace the transistor separately.
You can check the speed regulator with a multimeter set to chain ringing mode. The speed controller circuit is not included in the common circuit acting as a result of a full button press. This starts the closure of the contacts. Two wires are connected to the electric motor of the screwdriver, the same goes for the battery button.
The power button is connected to the control element or the field effect transistor through 3 wires, which is located outside the screwdriver case. It is necessary to connect the probes in order to dial 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 wire of the motor of the device, but also are mounted on the input contacts of the reverse. The device can indicate whether there is a contact or not. Then, in the same way, all measurements are carried out for another wire, which is the input. After that, turn the reverse lever to repeat the measurements. If there are no contacts, then these changes affect the button.
The cause of the breakdown should also be looked for in the brushes of the screwdriver motor.
If all the elements of the device are in good condition, as shown by the operations that were performed earlier, then they must check the condition of the engine brushes. This can be done by disconnecting the engine from the button by attaching 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. At the same time, anchor breakage is not excluded, which can occur in rare cases. Winding breakage may also occur. In this case, the engine is completely replaced. If only brushes are worn, then you can restore the screwdriver engine with your own hands.
To restore the engines of some models of screwdrivers, only brushes are changed, and they do not completely disassemble the element. To repair other models, the back cover of the engine is separated with brushes from its body. To this end, rolling of the lid is unbent, not touching its edges, because they must be returned after completion of assembly to their original place.
Flexible wire brushes are connected based on the spot welding method for attachment to the holder. Soldering wires for new brushes is possible. For this purpose, you can use only refractory solder.
Screwdriver motor repair
When working with a screwdriver for a long time, the bearings may wear out or become clogged.
Before starting the assembly of the screwdriver electric motor, with a thin wire that serves as a clamp, each brush is retracted in the brush holder, the lid is replaced. In this case, the brushes release and bend around the case at 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 pressing the tool. The cartridge, turning on the shaft, sometimes causes a strong beating during operation of the device. The support sleeve or shaft bearing may become very worn. As a result of damage to the sleeve or only the bearing, and not the shaft, replace only them.
Sometimes starting the engine is not possible for a certain fraction of a second, that is, it abruptly stops. This may be due to gear failure. Often, a malfunction occurs due to a breakdown of the pin, which serves as a mount to the satellite. It is possible to replace the carrier or the entire gearbox, which may fail if the gear teeth are worn.
If after carrying out all the above operations no malfunctions were found in the device, it is necessary to check the condition of the armature and the condition of the engine brushes. In this case, the motor should be disconnected from the switch button, and then measure the resistance by connecting a tester of any kind to the motor wires. If the resistance in the circuit is completely absent, then this may indicate that the brushes are worn out. Malfunctions in the motor armature are not excluded, which may be due to rupture of the winding. However, these types of problems can be rare.
If the engine armature is completely burned out, then the engine of the device is completely replaced. If only the engine brushes wear out, it is better to repair the device yourself. Before starting repairs, gently open the motor case of the screwdriver so as not to damage its edges. All stages of the work related to the replacement of brushes are indicated above. It is possible that the armature bushings were worn due to the magnet, which came off and began to come into contact with the anchor. Dripping a drop of special oil on the bushing, turn off the engine to wait until the oil has dispersed throughout the bushing. However, it still requires replacement over time.