In detail: do-it-yourself cordless screwdriver repair from a real master for the site my.housecope.com.
The screwdriver is a mobile tool that makes it easier to work with fasteners and screw connections. Until recently, cordless screwdrivers could only be found in the arsenal of professionals, but with the advent of inexpensive household models on the wide sale, their popularity has increased dramatically.
Unlike an expensive professional tool, budget counterparts have a smaller resource, which is why they often fail.
One of the weakest points of a household screwdriver is the start button and reverse switch. As practice shows, it is they that break most often.
As a rule, it all starts with the fact that the soft start function stops working, then a stronger pull on the "trigger" is required to start the electric motor.
Over time, the tool ceases to respond to any manipulation altogether. Often there is a problem of the opposite nature, when the motor starts to work spontaneously.
In some cases, to eliminate the defect, it is enough to disassemble the tool and clean it, although more often a complete screwdriver button replacement... In both the first and second cases, you can fix the problem yourself. Everything in order.
The screwdriver button is the main control element that performs several functions at once:
Turn on / turn on the instrument;
Switching the direction of rotation;
Smooth engine start;
Speed control.
However, each of the controls built into the button block cannot work correctly by itself. Except for the direction of rotation switch, which is usually a separate function block.
Video (click to play).
In most cases, the body consists of three conventional compartments, in which the working units and mechanisms are located.
In the lower part of the body there is an on / off control unit and an electric motor speed control unit.
In the middle part there is the "trigger" of the smooth start (the deeper you press it, the higher the rotation speed of the cartridge). When pressed, the button slides in a special block along the guides, a variable resistor is responsible for adjusting the speed.
In the upper part there is a reverse button - a switch for the direction of rotation of the cartridge. The direction is reversed by reversing the polarity of the voltage applied to the switch.
This is approximately how all control units of screwdrivers of different brands are arranged. To familiarize yourself with the device of a button of a specific instrument model in more detail, we recommend that you study screwdriver button diagram (it is in the instructions).
To diagnose and repair a screwdriver, you will need the following tools:
As a result of active use of any power tool, dirt inevitably accumulates inside its body.
Once in the control unit, it prevents the full movement of the "trigger" and blocks it.
Therefore, before going to the store for a new block, you should try to clean the old one. The carbon deposits formed on the contacts should also be cleaned with fine sandpaper. If the button is non-separable, the entire unit will have to be replaced.
Diagnostic steps:
We disassemble the tool body. To do this, we disconnect the battery, unscrew all the screws (they can be hidden behind decorative overlays that will have to be removed).
We check the serviceability of the electric motor. To do this, disconnect two power wires from the control unit and connect them to the battery contacts (the engine should start working).
We disassemble the screwdriver button. To do this, squeeze the plastic latches and separate the two parts of the button housing.
We make a visual inspection of the state of the button for dirt and damage.
Next, you need to carefully assemble the screwdriver button, install it in place and test.
VIDEO INSTRUCTION
If the cleaning of the control unit did not work, it is necessary to replace the entire button unit.
Disassemble the screwdriver (the process is described above);
Install the new button in place of the old one;
Connect the motor to the button terminals (polarity is not necessary in this case);
Assemble the screwdriver by carefully placing the wires in the case.
It is very important to choose a button for a specific model of a screwdriver, since with all the external similarity and visual correspondence, the part may not fit into the grooves. Typically, new buttons are sold complete with battery terminals and a transistor.
Many people probably have electric screwdrivers, battery-powered flashlights, etc. at home. in which the batteries do not pull.
My screwdriver has a fully charged battery for a couple of three screws.
Batteries in a screwdriver, cadmium in flashlights, as a rule, lead, all of them are now quite problematic to get for replacement. That will give us the conversion of devices to lithium.
1. Simplification of charging. Charging from micro usb, no need to look for where you put your own charger or where the wire from the flashlight.
2. The lithium battery is easier to find. For example, I generally took cans from an old battery from a laptop (you can find it either for free or for minimal money).
3. When replacing cadmium. There is no memory effect and you can charge at any time without waiting for a complete discharge.
4. Bigger than the standard battery capacity, often even when using a used unit. cans.
And so what we need.
1. Charge controller board, for example, on the TP4056 microcircuit. It is sold by the Chinese on Ali ebau and other sites. A clip will be sent for a dollar.
Available in two versions with and without overdischarge protection. It makes sense to use it with protection if there is no protection board in the battery itself. For 18650 batteries and the like, the protection board is usually installed on the negative terminal, if the negative is not made of metal, but of PCB glass, then this is the protection board.
The boards are similar in size. (left with protection from right without)
WARNING. For an electric screwdriver, battery protection cannot be used with a protection current of about 3A, and although the total consumption of a screwdriver is not large, inrush currents cut out the protection.
Here is a circuit board with battery protection (found on the Internet). Also in the appendix I will add documents for microcircuits.
The Chinese boards have a charge current of 1A if you want to charge from a computer port or from a weak charge, you must reduce the current to at least 0.5A. To do this, you need to replace the 1.2K resistor connected to the second leg of the TP4056 microcircuit with a larger resistor, for a current of 0.5A with approximately 2.4K resistance (the table of charging currents depending on the resistance is given in the document on the microcircuit).
I am planning on being able to charge from a computer and am replacing this resistor. Soldering and cleaning the pads.
Since it was only available with a nominal value of 2.2K, it received a charge current of 0.52A. What I considered acceptable for charging from a computer port.
2. The battery can be either bought a new one or removed, for example, from an old laptop battery.
My battery contained 6 cans connected in pairs. It is advisable to disconnect all the batteries (one of the cans was completely dead in one of the pairs) and measure the residual voltage. If there is a choice, then take banks with a large residual voltage, as a rule, and they also have more remaining capacity, although of course it is better to measure the real capacity. The battery was at 4000 mA i.e.at 2000 mA per jar, the residual capacity was noticeably 1200-1400 mA, depending on the jar.
Metal strips of contacts are welded to the batteries; they do not need to be torn off, but simply cut between the banks. It is convenient and safe to solder wires to them. The metal on the contacts of the batteries themselves is harder to solder and if you hold the soldering iron for more than a second, then there is a danger of overheating the battery, which will disable it until it burns out.
3. Wiring soldering iron tester, files, glue gun, etc.
We remove the batteries and standard charging for them. (if there is a backlight and for the flashlight it is desirable to measure the current of the LEDs on a fully charged battery)
Thinking about where to place the new battery and charging board.
Now, one of the longest stages is the finalization of the case.
To speed it up, it is better to use mechanization.
For example, Chinese cutters.
But I like the old Soviet ones better, they have better control and are less distracted. But unfortunately on sale they are more difficult to find.
We choose the extra plastic, making sure that the mini USB connector is minimally recessed.
We solder the circuit by connecting the battery and charging. And we check the operation of the charging and screwdriver, also if there are lighting LEDs, we measure the current consumption from lithium and the resistance of the damping resistor.
If the current of the lighting LEDs is very different from the current on the standard batteries, then we adjust the resistance of the balancing resistor. I soldered another resistor in parallel.
Next, degrease the body and all the parts with isopropyl alcohol or good gasoline in the shoe (ethyl alcohol does not degrease). And we fill in all the components from the hot glue gun. Excess, if that is not difficult to cut off with a knife.
After assembly, pour glue from a pistol into the holes that are intended to indicate charging.
When the glue has cooled down a little, it is easy to clean off the excess. As a result, the glue acts as a light guide and the battery is clearly visible when charging.
Alteration of another screwdriver. Now the battery can be charged without removing it from the screwdriver.
The battery is removable. (After the alteration, a micro USB connector and a charge indicator appeared on it)
A set of cadmium batteries and contacts were attached directly to the batteries.
With the help of hot melt glue I made a clip of contacts.
I placed the charger in the back and soldered all the components.
Redesigning the flashlight with a lead battery and charging from the mains took even less time since nothing had to be undermined.
The screwdriver belongs to the category of tools that are often used not only when performing construction and repair work, but also in everyday life. Over time, any mechanisms tend to break, which happens with screwdrivers. If such a thing happened, then there is no need to rush to throw away the tool, since you can perform an independent repair of the screwdriver. From this article, you will learn how to have a screwdriver repaired without the help of specialists.
To start repairing a screwdriver with your own hands, you should familiarize yourself with its design. The main element of the screwdriver is the electric motor. Screwdrivers are of both mains and battery types. The use of a network screwdriver is used less often, due to such a drawback as the need to connect the tool to a 220V network. Battery-type tools are more popular, as they allow you to carry out repair work not only at home, but also outside it.
The main components of the cordless screwdriver are:
Frame. Usually all screwdrivers are made of durable plastic.
Start button. It is designed in such a way that the number of revolutions of the cartridge depends on the force of pressing on it.
Electric motor. In cordless tools, single-phase motors of the collector type and direct current are used. The motor is a rotor, a stator in the form of magnets, and a brush assembly.
Reducer.
Force regulator.
Reverse switch.
Battery. As a rule, it is removable and often comes with a duplicate product.
