The screwdriver can be repaired independently, having studied its device and the principles of operation of individual units.

Device and faults of the screwdriver

All screwdrivers are arranged approximately equally. They consist of the following functional units:

• the start button;
• pulse-width controller;
• the electric motor;
• transistor;
• planetary reductor.

All components of the device are in a durable and aesthetic housing, which has a rubber grip, control buttons and adjustment, and also a socket for installation of the accumulator (if the screw driver is designed only for operation from a network of 220 V, it is not).

When you press the start button, the screwdriver can not fully squeak. This is a normal phenomenon of the operation of DC motors at start-up and at low revs.

Why and how to adjust the ratchet

The ratchet screwdriver is a coupling designed to limit the force during the rotation of the cartridge. Its presence in the power tool can be determined from a rotating ring with numbers. Some users do not understand the value of the coupling and do not touch it. Using a ratchet, it is possible to adjust the depth of screwing of the screw. In too soft material, the fastening screw can easily be heated and can pass through. When using small fasteners, a very high torque can destroy it.The ratchet prevents cutting of the slot at the screws and the wear of the bits of the screwdriver. To determine the desired value on the adjusting ring, make several approaches, starting with the minimum.

If the screwdriver has a drilling mode, the last icon on the coupling will be an icon with a drill image. In this position, the maximum torque is used.

Frequent faults in the screwdriver

Since all modern screwdrivers have a standard device layout, they also have typical faults. The main defects of this tool include:

• battery failure;
• wear of brushes;
• failure of the button;
• beating of the cartridge;
• no reaction to attempts to turn on or off;
• work with interruptions.

All these failures you can eliminate yourself if you have experience with measuring and soldering devices.In some cases, you will have to change the nodes completely, since not all parts are sold separately. If the repair of the gear or motor is too complicated for you, these elements can be completely replaced or carried to the workshop.

Screw driver repair with own hands

To eliminate most of the faults of the screwdriver, its disassembly is required, i.e., Removing the case and detaching the main components from each other.

How to disassemble a screwdriver

The screwdriver is disassembled in the following sequence:

1. Remove the battery.
2. Unscrew the screws that connect the two halves of the case.

   The case of the screwdriver consists of two parts, connected by a rather large number of screws - in order to disassemble it, you need to find all the fixing points

3. Remove its upper part.
4. Take out the contents.
5. Disconnect the button.

   The screwdriver button is integral with the switching mechanism, which is connected to the motor, so when you detach the button from the socket on the case, you must be careful not to tear wires

6. Remove the speed selector.
7. Disconnect the engine, gearbox, adjusting clutch and chuck.

   In order to detach the screwdriver gear reducer from its engine, it is necessary to unscrew the four screws that are in place of the contact of the two plastic casings

Video: how to disassemble a screwdriver

Cartridge repair

Cartridges in different models of screwdrivers may differ slightly from each other. They can be attached to the shaft in three ways:

1. Morse cone.
2. Threaded connection.
3. Threaded connection with fixing screw.

To determine the way of mounting the cartridge, you need to read the inscription on its sleeve:

• marking "1-6 V10" means the Morse cone. A nozzle with a shank diameter of 1 to 6 millimeters is used. The code "B10" denotes the size of the cone. Take the hammer and beat the cartridge with blows on the body;
• inscriptions of the type -11 M12x or "2-13 mm ½-20 UNF" mean the metric and inch threads.

If the cartridge is threaded, you need to do the following:

1. Unclip the cams of the cartridge.
2. If there is a screw inside, unscrew it clockwise (the screw has a left thread).
3. Take the hexagonal L-shaped key with a size of 10 mm.
4. Short edge insert into the socket and tightly clamp in the cams.
5. At low speed, start and immediately turn off the screwdriver so that the long edge of the hexagon strikes the table. Instead of turning on the device, you can simply hit the key with a hammer. The thread will move and the cartridge will wriggle out.

   In order to remove the cartridge, it is necessary to clamp the hexagon key in it and start the engine at low speed until the key strikes the table

Video: how to remove a cartridge with a thread using a hexagonal wrench

If these methods do not help, disassemble the screwdriver and remove the reducer assembly. Take the L-shaped tubular key (most often 19 ") and unscrew the cartridge, holding the bolts of the reducer fastening on the back of the reducer with the spanner head of the key. It will give the necessary emphasis, with which the cartridge can be unscrewed by hand.

Video: how to remove the cartridge with a tubular key

To disassemble the cartridge, you need to remove the cap at its base. The plastic plug is gently pricked with a knife. Metal - knocked out by hammer blows on the base of the cartridge:

1. Take a large bolt, insert it into the cartridge and slightly press it down to center it. The bolt head should protrude two or three centimeters above the cartridge.
2. Hit the hammer on the head of the bolt. The cartridge will pop out of the case.

Video: removing the plastic cap from the screwdriver holder

Common malfunctions of the cartridge:

• crookedly clamps the bits;
• backlash between bits and cams;
• the cams are unevenly protruding.

To find out the reasons and solve them, follow these steps:

1. Disassemble the cartridge.
2. Remove the tapered nut, which consists of two parts.
3. Unscrew the clamping jaws.
4. Check the condition of threads on the nut and on the cams, replace the defective parts.

   In the process of working on the cams or the tapered nut that controls their work, the thread can be worked out or crushed, then these parts need to be replaced

5. Assemble the cartridge in the reverse order to the disassembly.

It should be noted that parts such as cams or a cone nut can not be purchased separately, they can only be removed from another similar cartridge. Therefore, in most cases, the defective cartridge is best carried to the workshop, or even easier - to buy and install a new one.To buy a new cartridge, take with you to the store a screwdriver and a dismantled old cartridge.

Video: parsing and repairing a cartridge with a metal plug

Battery repair

Three types of batteries are used in screwdrivers:

1. Nickel-cadmium (Ni-Cd). They can be recharged many times, but they have a memory effect. If you do not wait for full discharge and start charging the battery, then gradually its capacity will decrease. Rinse out the battery before first use. Empty the battery three times and recharge it to maximize the capacity.
2. Nickel-Metal Hydride (Ni-MH). A feature of such batteries is a less pronounced memory effect, but a high self-discharge current. If you intend to store the screwdriver without using for more than a month, be sure to fully charge its battery.
3. Lithionic (Li-Ion). These batteries are quickly charged, but do not tolerate frost. They can be charged when convenient.

Store all types of batteries separately from the screwdriver and charger. With long non-use, they need to be recharged once a month.

If the battery does not hold a charge, disassemble it. It consists of several batteries. Check the tester for voltage in each. The value of the operating voltage is indicated on the housing (it is the same for all elements). Replace non-working batteries.

Video: eliminating the rapid discharge of the battery

If the battery is not removed, most likely, the fixing button wedged. It is necessary to remove the upper part of the case, disconnect the battery, disassemble it and adjust the button.

Repair of the charger

Frequent damage to the charger:

• the fuse is on;
• breaks the network cable;
• breaks the primary winding of the transformer;
• break through the diodes.

If you disassemble the screwdriver charger, then we will see the step-down transformer and board. Through the mains lead, the voltage is applied to the primary winding of the transformer. The thermal fuse is connected in series with the mains winding, therefore it overheats first and protects the winding from the breakage. From the secondary winding voltage goes to the diode bridge. If the charge passes current, yellow is formed around the diodes. The transformer windings overheat, the diodes break through.

1. Measure the resistance on the primary with a multimeter. If it is not there, then the circuit is cut off and no voltage is applied to the primary coil. The fuse is located under the transformer insulation near the wires connecting to the network. Check it with a tester.
2. If the fuse is full, check the network cable, it may be interrupted.
3. If the wire is OK, check the windings. In case of a breakdown, replace the transformer.

Video: diagnostics and repair of the charger

Problems with the button

A malfunction of the start button may lead to the following violations of the screwdriver operation:

• appears self-propelled;
• the device does not turn on;
• the device is unstable.

From the button, two wires go to the battery terminals and two wires to the engine. If there is a transistor, then it is connected by three wires. Verify that the problem is in the button:

1. Connect the battery. Press the button and the tester measure the voltage at its output, it should be absent.
2. Remove the battery and remove the top motor cable from the button body.
3. Connect the motor directly to the battery. To do this, take two wires of the required length and connect them to the battery terminals. Connect the other ends of the wires to the motor housing and to the wire that was inserted into the button. If the engine is working, then the button is faulty.

Video: diagnostics and replacement of the screwdriver button

Sequence of button repair:

1. Wires coming from the button, it is not necessary to solder. Gently, in order not to damage the base, remove the pushing part of the button, which does not fall into the inner area of ​​the case. This should not be done in a jerk, but slowly rotate and pull on yourself.
2. Remove the protective cover. Take the knife and the flat screwdriver. Pry and release all latches. Pull out the element number 1 and remove the cover of the switch compartment at number 2. If the contacts are slightly burned, they should be cleaned. But if they burned completely, then the button is best replaced. It is sold complete with wires. If the contacts are intact, then we go further.
3. While holding the spring, gently remove the switch mechanism. Look inside. Perhaps, because of the poor quality of the metal, the contact areas were erased and dust formed, which settled inside the plastic box. Accordingly, dielectric surfaces began to conduct electric current. This is one of the reasons for the spontaneous operation of the device. The second reason is a failed transistor. Remove the metal dust with cotton wool soaked with alcohol. Contacts can be scraped with a knife, but not with sandpaper, so as not to spoil their surface. Now gather everything in the reverse order. Burn the replaced transistor. Turn on the tool.

   The cause of the failure of the button may be burnt contacts, metal dust or a burnt transistor

Inspection and repair of the force regulator

Behind the cartridge there is an adjusting ring with a spring that controls the force and flips the cartridge away from the reducer. This spring presses on the balls, which abut against the projections of the ring gear of the reducer. Disassemble the ratchet, check the integrity of all its elements. Remove the dirt with a cloth moistened with alcohol, grease the balls.

Video: rattletrap repair

Disassembly and repair of the reducer

Basic elements of the reducer:

• gears;
• drove;
• satellites.

They are made of metal and plastic. The ring gear is a cylinder with internal teeth all along the circumference. The teeth are moved by satellites.

The first carrier has two gears at both ends. The first solar - drive gear of the engine. It comes between the satellites of the first carrier. The second solar on the opposite side comes between the satellites of the second carrier. In the two-stage gearbox, the second carrier is connected to the shaft to which the cartridge is to be worn. The three-speed reducer has one more mechanism. All these parts are located inside the ring gear.

The engine transmits the rotation to the satellites of the first stage through the sun gear. The first carrier rotates the second stage of the satellites. If there is a third stage, then the second carrier rotates it. The satellites of all stages rotate inside the ring gear. The last carrier rotates the shaft of the cartridge. With each transmission of torque, the speed drops.

Sequence of disassembly of the reducer:

1. Removing the cartridge.
2. Unwinding the case.
3. Disconnect the gearbox from the engine.
4. Removing the plate.
5. The removal of all parts from the shell.

   When disassembling the gearbox, all the parts are taken in series: first the satellites of the first stage, and then the second

6. Unscrewing all bolts that connect both halves of the reducer.
7. Correction of the diameter of the spring using pliers in order to improve the inclusion of the transmission.
8. Disassembly of the coupling by removing the lock ring, washers, bulk bearing.
9. The removal of the shaft.

All the details of the gear unit to be dismantled in order to be easier to assemble later.

1. If a scraper is heard during the operation of the screwdriver, or it jerks, then the reducer has defects. During operation, it is necessary to make lateral pressing and heavily load the tool. Because of this, the reducer shaft warps and there is noticeable runout. In this case, the assembly is assembled.
2. If the bearing bushing and the shaft bearing wear out, they can be replaced by similar ones.
3. The breakdown of the pin of the satellite is accompanied by the start and instantaneous stop of the engine. Replace the carrier or gearbox.
4. Wearing gear teeth also requires a gearbox change.

Often, the repair of the reducer is limited only to cleaning and lubrication.Do not overdo with grease, otherwise the device will not work properly.

Video: disassembly, assembly, cleaning and lubrication of the reducer

Brush replacement

Graphite brushes are located from the end of the engine on the side of the connection with the button. They can be located inside the engine housing under the rear cover or outside. If you wear at least one of the brushes by 40%, change both. Check the contacts. The following signs indicate the wear of the brushes:

• the engine runs in jerks;
• audible unusual sounds;
• sparking;
• the smell of burning.

  When removing and installing the brushes, you need to hold the holders, otherwise under the action of the spring they can fly away quite far

Video: engine brush replacement

Engine repair

The screwdriver uses a DC motor in a cylindrical housing with magnets. Inside there is an anchor with windings and brushes. To check the engine, disconnect the reducer and the wires leading to the button, and measure the resistance of the armature winding with a multimeter. The absence of an instrument indicates a break, and a very low value indicates a short circuit. The collector resistance is measured on the shaft and each plate. It must be zero. Malfunctions in the anchor lead to shutdown during operation, loss of power, sparking and smoke.

Video: testing of armature winding and collector plates with multimeter

Often when the engine fails, the gear remains intact. Since in most engines it is pressed on the shaft, its removal takes place with some difficulties. Buy a special puller or use improvised tools.Do not try to do it with pliers or nail - you will bend the shaft and spoil the gear teeth.

1. Take a piece of profile or channel. Make a longitudinal groove with a bulgarian.
2. Insert the shaft into the groove perpendicular to the profile and, as it were, pry the pinion.
3. Lay the profile on two solid surfaces so that the motor is hanging between them.
4. Take a nail and gently knock on the edge of the shaft with a hammer. The gear is easy to slide.
5. Put the gear on the new engine with a hammer and a hard surface.

Video: remove the gear from the motor shaft

Shurupovort cracks, but does not twist

When there is a crack in the operation of the screwdriver, first try changing the position of the speed controller. Perhaps he was not included. If this procedure does not work, disassemble the tool.

1. If the engine turns, disconnect the socket. Check the rotation of the gearbox shaft and the state of the engine gear.
2. If the shaft does not rotate and the gear is complete, disassemble the reducer. Check the condition of the teeth of the pinions and gears.
3. If the engine does not work, check the brushes, windings and anchors.

Now you know how to disassemble, assemble and repair a screwdriver with your own hands.