An ordinary soldering iron: we study it and bring it back to life. Everything about the rules for operating an electric soldering iron and repairing it yourself. Resistance of the heating element of the soldering iron.

An electric soldering iron is a hand-held equipment that allows you to soft solders connect parts together, heating the solder to a liquid consistency, filling the voids between the elements being connected. Before purchasing a tool, you should familiarize yourself with technical characteristics device, operating rules and how to repair a soldering iron.

A soldering iron is a tool necessary for performing minor repairs on electronic devices.

terms of Use

There are models on the market that are suitable for operation from a network with voltages from 12 to 220 V. In the process of choosing a tool, the need to ensure the safety of the craftsmen working with it and the voltage in the electrical network at the work site are taken into account.

In rooms with high humidity levels and grounded devices, it is permissible to use a soldering iron with a voltage of up to 36 V and mandatory grounding of the soldering iron body. There is no need to repair the instrument if these requirements are met.

Electric soldering iron device.

At self-production soldering iron uses a thin wire to wind the spiral. The supply and tool voltages must match each other. The power of such units reaches from 12 to 100 W and higher, because it is possible to ensure that the solder spreads evenly over the surface of the elements being connected if they are heated stronger than temperature its melting. Heat from the tip is transferred to the parts upon contact, because of this the temperature of the tip decreases.

Insufficient power of the heating coil or small diameter of the rod may prevent the tip from heating to the required temperature, which prevents soldering. Powerful soldering irons can be used to connect small parts, but due to the size of the device, access to the soldered elements is limited. Experts recommend winding a copper wire with a diameter of 1 mm around the tip. High power similar devices allows you to quickly warm up elements, and most small radio components, transistors, diodes, microcircuits cannot withstand temperatures exceeding 70 ° C. Soldering time is reduced to 3 seconds. Before you repair the device in question, you will need to find out its design features.

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Components

Diagram of a miniature soldering iron.

The device in question is made of a copper rod, which is heated to the melting temperature of the solder using a nichrome spiral. When soldering parts, it is necessary to ensure that heat is quickly transferred from heating element sting.

The tip is the working part of the tool, a rod with a wedge-shaped tip. It is inserted into a steel tube wrapped in fiberglass cloth or mica, on which a wire is wound, which acts as a heating element. Nichrome wire is wrapped with asbestos, which helps reduce heat loss. To the conductors electrical cord The ends of a nichrome spiral are connected to the plug, which are bent and folded in half to ensure greater reliability and reduce the heating temperature at the points of connection with the copper wire. The connection is additionally crimped with a metal plate.

The spiral made of a nickel-chromium alloy and the sting made of copper are located in a metal casing, which can be made from a solid piece of metal or welded from 2 parts. The housing is fixed to the metal tube using overlay rings. After inserting the plug of the device into the socket, the electric current is supplied to a nichrome spiral, which, after heating, transfers heat to the tip.

An attachment for a soldering iron for soldering small parts.

Experts recommend using equipment with a power of no more than 12 W for soldering low-power diodes. Thick wires, large parts and small powerful parts need to be soldered using 40 and 60 W devices. Large parts are soldered with units of 100 W or more.

The quality of work cannot be guaranteed by selecting the correct power tool. Incorrect operation of the unit leads to breakdown and the need to repair the soldering iron.

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Step-by-step instruction

Independent production or repair of heating devices is carried out taking into account the calculation of the resistance of the heating element or winding. Knowing the voltage and resistance values of an electrical appliance allows you to calculate its power that it consumes. The resistance in the winding of a 60 W soldering iron, powered by a 36 V network, should reach 22 Ohms. Correct selection power and voltage helps to avoid breakdowns and the need to repair the device in question.

Schemes of temperature controllers for the soldering iron tip.

Then you need to select the diameter of the nichrome wire, comparable to the dimensions of the winding. The spiral winding with a resistance of 806 Ohms is performed using 5.75 m of wire with a diameter of 0.1 mm (the resistance value is divided by 140) or 25.4 m of wire with a diameter of 0.2 mm. The coils must be laid closely. The surface of the nichrome wire will oxidize when heated, creating an insulating surface. The wound layer, which does not fit into the first row, is covered with mica. Wind up the second row. High-quality assembly allows long time operate the tool without breakdowns or repairs.

Thermal and electrical insulation in the winding is provided by a coating made of fiberglass, mica or asbestos. The advantage of asbestos over other compounds is that it can be soaked with water, creating the required shape, and after drying, the material has a fairly high strength.

The main cause of soldering iron malfunction is a broken heating element.

Simple repairs help restore its functionality. To repair a soldering iron, you will need the following tools:

pliers;
sharp knife;
ceramic resistance “PEV-10”;
asbestos thread.

Repair of an electric soldering iron is carried out in several stages. A 1-1.5 Ohm ceramic resistor is pre-prepared. In its central part there is a hole that allows you to pass the soldering iron rod without additional adjustment.

The faulty heating element is then removed. A prepared ceramic resistor is placed in the resulting socket. Next stage consists of connecting power wires to a resistor. To do this, it is recommended to use the channels in the handle of the device. The wires must be laid so that they do not come into contact with the body, and the terminals must be insulated with asbestos thread. Upon completion repair work will need to be collected constituent elements soldering iron in reverse order. To repair a soldering iron yourself, you will need its circuit diagram.

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how to repair a soldering iron with your own hands

An electric soldering iron is a hand-held heating device for fixing metal parts using solder - an alloy heated to a liquid state and having a melting point lower than that of the workpieces being fastened.

Soldering iron repair

Design

The operation of electric soldering irons requires knowledge of their designs in order to quickly identify damage and repair the device at any unexpected moment. It consists of:

a copper rod wrapped in insulating material and placed in a steel tube;
heater;
tips for directly connecting metal parts with solder;
handle holder;
cord with plug.

The copper rod is an effective conductor of heat from the heater (nichrome spiral) to the tip. The spiral is wound onto a steel tube, which is wrapped in mica or fiberglass. Next, the nichrome winding is covered with an insulator (preferably asbestos), which prevents heat loss and short circuits.

Nichrome heating spiral

To reduce heating in the area of connection with the conductors of the power cord, the ends of the spiral are bent in half, and the contact point is supplemented with a crimping aluminum plate. Electrical insulation is ensured by insulating tubes placed at the twisting point.

The rod and heater are placed in the body of the soldering iron, onto which a wooden or thermoplastic handle with an internal channel for the power cord is attached.

Operation

The operating principle of a soldering tool is based on the conversion of electrical energy into thermal energy, which heats the tip through heating the coil and rod. The temperature in the soldering zone reaches 400-4500C. The resulting viscous-liquid mixture penetrates into cavities and irregularities between parts. After cooling, the metals will be securely connected.

Additional Information. The electrical circuit usually contains an AC to DC converter.

Power

The operating power of the soldering iron is selected from 12 to 3000 W and determines it technical capabilities. Soldering of small parts is performed with a 12 W device. This condition must be met, since a powerful soldering iron, due to the size of the tip, will not be able to reach the contact points of tiny radio elements. In addition, the high power of the device causes unacceptable overheating of the circuit parts.

Soldering iron 12 W

For powerful radio components, thick wires and small elements Soldering irons 40 and 60 W are required. If work is performed on large equipment, then the soldering tool is selected for 100 W or higher. If the power of the device is insufficient, the soldering will be weak and have a large number of voids.

Voltage

To comply with safety precautions, the soldering iron is selected according to the mains voltage from 12 to 220 V (5 values in total). Thus, work in passenger vehicles can be carried out with a soldering tool at 12 V, in trucks - 24, in air - 27, in a damp room with mandatory grounding of electrical equipment - 36 V.

It is not easy to convert a 12 V tool to 220 V - you will have to wind a thin spiral with a large number of layers, which creates certain inconveniences when working with small parts.

Note! If the power of the network and the soldering iron match, you can work from alternating and direct voltage. This possibility is due to the nichrome material of the heater.

Basically, the voltage in soldering tools is 220 V. To prevent electric shock in high humidity or dusty areas, use a tool voltage of no more than 42 V.

Kinds

The most popular types Soldering irons can be classified into two categories: heating features and design types.

According to the heating principle, soldering devices are distinguished:

nichrome;
ceramic;
induction;
pulsed.

Nichrome

The most common soldering iron device is with a spiral heater made of nichrome, through which direct mains current or alternating current from the mains and transformer can pass. This tool is affordable and shock-resistant. Suitable for infrequent use.

Ceramic

In this type of soldering iron, the heater is a ceramic rod through which thermal energy from the live contacts passes. Among the advantages noted: long service life with proper operation, fairly fast heating, the presence of a temperature and power control system, compactness.

Ceramic soldering iron

Disadvantages include: fragility of the ceramic rod, use of only the original tip, high cost, the risk of purchasing a nichrome fake.

Induction

The inductor coil, as the main working part of the soldering iron, creates a magnetic field and heats the core. Heat is transferred to the tip, which is maintained at a temperature thanks to the ferromagnetic coating.

Each metal and part requires its own heating, so the tip must be selected individually.

Pulse

The pulse soldering iron circuit contains: a frequency converter, transformer high frequency and sting. An electrical impulse occurs with increasing frequency mains voltage, which through shortest time decreases to the required value.

The tip is connected using clamps (current collectors) to the secondary transformer winding. Thanks to this, when you press and hold the start button, the end part of the tool instantly warms up.

Pulse soldering iron

Soldering irons of this type are designed for short-term soldering of parts of various sizes.

According to design differences, soldering devices are divided into:

rod - the handle-holder turns into a straight rod with a sting;
pistol type - handle and metal part perpendicular to each other;
soldering stations are complex devices with built-in electronic unit According to operating technology, adjustments are divided into infrared, thermal air, and digital.

There are models of soldering irons for children's technical modeling - low-power with wooden handle. Compact USB devices powered by car cigarette lighter, and hammer soldering irons are equipped with a thick tip for large parts. Cordless and gas tools are self-contained devices and are powered by a battery and a gas cartridge, respectively.

Soldering tools can have tips of various configurations (wedge-shaped, cone-shaped, chamfered, needle-shaped), made of copper or additionally nickel-plated. The handle is made of material with low thermal conductivity: wood, ebonite, textolite.

Note! Before work, you must familiarize yourself with the rules for operating and repairing the soldering iron.

terms of Use

Soldering iron repair is unlikely to be required if you follow the necessary operating rules:

ensure safety precautions at the workplace in accordance with the product instructions;
take into account the value of the mains voltage;
in rooms with high humidity, use a 36 V device (no more), first grounding it;
The heater and cord must be free from mechanical loads during operation;
do not touch the cord with a hot tip;
do not overheat the soldering iron coil;
select the heating mode using the power regulator.

Important! Correct selection of power parameters does not guarantee the quality of soldering.

Causes of damage

The most common reasons for soldering tool failure are:

damage to the plug or cord;
network failure;
violation of work contacts;
heater failure.

How to repair

To prevent sudden damage to the instrument from causing inconvenience, every specialist or radio amateur must confidently wield a soldering iron and be able to repair it, especially since it is not difficult. It is necessary to have a conventional ampere-voltmeter that diagnoses the type of malfunction.

Household ampere-voltmeter

Replacing the heater with a new one

If the heating element loses its functionality, do the following:

determine the winding resistance based on the power of the device and the network voltage;
choose the diameter nichrome wire by resistance per 1 meter;
wind the spiral, laying the turns without gaps, placing a layer of mica between the rows;
in order to retain heat and prevent short circuits, the winding is covered with fiberglass, instead of which mica or asbestos can be used; the latter has the advantage of creating the required shape and acquiring strength after drying.

Note! After applying the asbestos insulating layer, you need to wait for it to dry and only then turn on the device to the network.

Replacing the heater with a resistor

Instead of a heating element, you can successfully use a PEV-10 resistor. To repair a soldering iron with your own hands, you will need pliers, a well-sharpened knife, and asbestos thread. To replace the heater, you must:

disassemble the soldering tool;
remove the used heater;
place the resistor in the vacant space;
remove 1.5 cm of insulating coating from the power cord, connect the power wires to the resistor through the holder channel; make sure that the laid wires do not touch the housing; insulate the terminals with asbestos thread;
assemble the tool and make sure it works.

If the power cord is damaged, it should be replaced. A faulty power cord plug must also be replaced. In this case, the broken fork (usually a solid one) is cut off and a collapsible one is installed instead.

Broken contact of the heater with the power cord can be easily eliminated. To do this, you need to disassemble the soldering iron and restore the connection of the contacts.

If you work with the soldering iron carefully, it will not require repair for a long time. If damage does occur, it is quite simple to fix it: you need to know the circuit diagram of the device (it is elementary), the basic rules of electrical engineering and safety.

Video

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DISASSEMBLY AND REWINDING THE SOLDERING IRON

If you, a fellow hobbyist, have already “outgrown” a soldering iron with a voltage regulator, but have not yet “grown up” in your ambitions to a professional soldering station, then this might be interesting. The ability to change the supply voltage of a soldering iron designed for 220 V, among other things, allows you to return to operation an already burnt-out one. And use it in the future, for example, with a switching power supply from an imported TV, which at the output gives exactly half of the network one. Bringing these two products together results in an intermediate option between a soldering iron with a regulator and a full-fledged soldering station. Any radio amateur can do this. I’ll show you how to do this using the example of changing the supply voltage of a Chinese-made soldering iron, which was not trustworthy for use without modification.

Disassembling the soldering iron

Mica with soldering iron spiral

Soldering iron rewind

Winding a soldering iron tip

As soon as I managed to reel required quantities nichrome, cut the wire with an allowance of 1 - 2 cm and wind it to the conductor. We put on the mica winding, passing the conductor into the slot in it and press it against it (naturally on top of it).

Soldering iron assembly

Tests

Heating rate

And here is a table that will help you navigate the required resistance of the heating element, depending on the desired power and the available supply voltage. Author: Babay iz Barnaula.

Electronics repair

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DIY soldering iron repair - studvesna73.ru

Have you purchased a soldering iron, but are not satisfied with the quality of its work? Then you will find in this article material on how to repair a soldering iron if you do not want to take it to a workshop, but decide to do it yourself. The video tutorial presented is about a cheap Chinese device in which some parts need to be replaced.

Unusual soldering irons are sold cheaply in a Chinese online store.

First, look at what you need to remake a soldering iron:

Soldering iron;
- thick copper wire;
- screwdriver;
- drill;
- the wire;
- wire cutters;
- electrical tape;
- fork;
- flux;
- tin;
- metal sponge.

The first thing we pay attention to is the ineffective soldering iron tip. replace it with copper wire required diameter. Let's take out the old tip and make it out of copper to the same size (thickness and length).

All that remains is to tin the tip and you can solder with the normal soldering apparatus you have modified.

Notes Another disease of Chinese soldering irons is severe overheating during operation. It can be eliminated by inserting into the gap one of the wires a diode with an operating voltage of at least 300 volts (it can be mounted in a power plug; the polarity of the connection does not matter). In order for the soldering iron tip to burn less, before work it must be forged in a cold state with a small hammer; in this case, the copper becomes denser and does not burn so quickly.

DISASSEMBLY AND REWINDING THE SOLDERING IRON

If you, a fellow hobbyist, have already “outgrown” soldering iron with voltage regulator. but I haven’t yet grown up in my ambitions to become a professional soldering station. then this might be interesting. The ability to change the supply voltage of a soldering iron designed for 220 V, among other things, allows you to return to operation an already burnt-out one. And use it in the future, for example, with a switching power supply from an imported TV, which at the output gives exactly half of the network one. Bringing these two products together results in an intermediate option between a soldering iron with a regulator and a full-fledged soldering station. Any radio amateur can do this. I’ll show you how to do this using the example of changing the supply voltage of a Chinese-made soldering iron, which was not trustworthy for use without modification.

Disassembling the soldering iron

To disassemble the soldering iron, it was necessary to completely unscrew the two screws connecting protective cover with a heating element and holding the tip, and three self-tapping screws securing the working part to the handle. Remove the insulation from the wires and unscrew the connecting twists.

Mica with soldering iron spiral

There is a heating element inside the protective casing. That's what they have to do. It is necessary to change the amount of wound nichrome wire - change the resistance of the heating element. Now it is 1800 Ohms, 400 Ohms are needed. Why exactly so much? Currently working with a UPS, the soldering iron has a resistance of 347 Ohms, its power is from 19 to 28 W, there is a desire to make the second one less powerful, so I added Ohms.

Soldering iron rewind

Winding a soldering iron tip

The tip is reinserted into the heater, clamped with screws and into the drill chuck. If you disassemble and unwind excess nichrome while holding the heating element in your hands, then everything will be much more complicated. The tie wire is removed.

The released fiberglass and mica wrappers are removed. In the mica on the side of the tip, there is a slot into which a conductor is inserted, going from the nichrome to the network wire - therefore, the weakened mica wrapper is removed from it rather than unwinding. Mica is a very fragile material. The end of the nichrome wire wound to the conductor is disconnected. Its thickness is just over 4 microns.

Nichrome must be wound onto something round, perfect option- spool of thread. He unscrewed it, rewinded it, and so on until the end. There is no need to disconnect the second end of the nichrome wire.

Soldering iron wire resistance

Now you need to wind a length of 400 Ohms, and in centimeters it will be approximately 70 (the total length of nichrome wire 300 cm is 1800 Ohms, hence 400 Ohms will be 66.66 cm). At a length of 70 cm, a latch (clothespin) is placed and in the hanging position of the coil, slightly guiding with your fingers, winding is carried out at intervals ensuring its termination at the first conductor. The number of attempts is not limited, the main thing is not to tear the nichrome. At the end of winding, a control resistance measurement is required.

As soon as we managed to wind the required amount of nichrome, we cut the wire with an allowance of 1 - 2 cm and wind it to the conductor. We put on the mica winding, passing the conductor into the slot in it and press it against it (naturally on top of it).

We install a fiberglass winding on top and, compacting it by pressing, wind the binding wire. A heating element designed for power supply voltage of 85 – 106 V is assembled.

Soldering iron assembly

Since the working part was previously attached to the handle with incomprehensibly clumsy and short screws, they had to be replaced. To do this, holes for new screws were deepened in the attachment points on the handle.

Before connecting the power cable with the conductors going to the nichrome heater, a plastic clamp was installed and adjusted on it.

The casing of the heating element ends with a kind of cooling radiator, through holes in it and is attached to the handle. To increase the cooling effect, the gap between it and the handle was increased using metal washers.

Soldering iron current consumption 190 mA

The UPS with which the soldering iron will work at the output under load gives from 85 to 106 V. Current consumption is 190 mA, this is at the minimum voltage. Power 16 W.

Soldering iron current consumption 240 mA

At maximum voltage, current consumption is 260 mA. Power 26 W. The desired has been received.

Finally, a test for heating duration. Up to 257 degrees in 2 minutes 20 seconds. An excellent result, if you take into account that from a 225 V network it heated up to 250 degrees in 5 and a half minutes.

Table. Dependence of the resistance of the heating element on the power and voltage of the soldering iron

And here is a table that will help you navigate the required resistance of the heating element, depending on the desired power and the available supply voltage. Author - Babay iz Barnaula.

Many people are guilty of fetishism. Everyone has their own object of adoration. I would venture to guess that for radio amateurs this is most often a soldering iron. So I had one like that until I decided to make an improvement - I put a diode in the break in the wire and a toggle switch to it. Well, everyone knows this rationalization and has been for a long time. Convenient, liked it. But the soldering iron burned out. In just a month. It's clear that it's a coincidence. I repaired it - I fastened (crimped) the ends at the burnout site with a piece of copper plate. And a month later again. The second plate did not fit in the heating element. A year has passed. And now, extracting from the board of an imported TV pulse block power supply, I figured out how to give a second life to a faithful partner - if there is not a sufficient length of whole nichrome wire (where can I get it with a diameter of 0.08 mm?) to wind the heating element at a voltage of 220V, then this can be done at a lower voltage, for example 110V, from the available “scraps9raquo; (you need less nichrome).

To begin with, I made measurements and calculations. I measured the resistance of an existing whole piece of nichrome - 367 Ohms. The output voltage of the power supply, took the value of 110V, divided by 367 Ohms and got the required current value - 0.3 A, multiplying it by 110V, I found out the estimated possible power of the soldering iron - 33W. Quite enough. The existing mandrel with a dielectric (mica) wound on top was placed in a cartridge hand drill, tied nichrome at one end to a conductor wire, and wound the other on an improvised bobbin, attaching clothespins for weight.

It's not ideal, though. The main thing here is that the turns do not touch each other. The second end of the nichrome to the second wire - the conductor. On top of the nichrome there is again a dielectric, of course you need mica, but there was none - in the photo there is an asbestos cord.

Conductors (wires) bend in in the right direction, the far one presses against the asbestos. The contact between conductors - wires must be EXCLUDED. On top is again a dielectric - mica.

Then everything is simple: we pass the wire coming from the plug through the handle of the soldering iron and the casing, and connect its cores by twisting with the conductors in contact with the nichrome, having previously put on the last insulators that were on them before disassembly. We insert everything into the casing.

Handle casing. The tip is inside the heating element mandrel.

Now be sure to “call 9raquo; the pins of the power plug relative to the casing and soldering iron tip! THERE SHOULD BE NO CONTACT.

“Chassis9raquo; the tests were successful. The fact that you shouldn’t plug this soldering iron into a 220-volt outlet is, of course, clear to everyone. And smooth temperature control, if necessary, is achieved according to this scheme. With best wishes, Babay. Russia, Barnaul.

Topic: what to do if a soldering iron burns out, how to restore it yourself.

Sometimes the soldering iron you use to solder various schemes, parts, wires suddenly stop working, it does not heat up. In most cases, it may be a simple break in the wire that powers the electric soldering iron itself. The most vulnerable point of the wire is the area where it is frequently bent. For a soldering iron (and not only for it) this is the place where the wire enters the soldering iron itself. You just need to disassemble it and ring the wires coming from the plug. If the wire does not ring, then simply cut off a small piece (about 15 cm long) from the entrance to the soldering iron. Call again. If there is still no contact, then cut the same piece from the plug side. Well, as a last resort, just install a new wire.

But not in all cases, the reason why an electric soldering iron does not work is a break in the wire powering it. Sometimes the heating element itself burns out inside the soldering iron. There are two ways to go here. You can try to rewind the heating coil yourself. This is a fairly simple task if you have something to rewind and if the soldering iron was designed for a voltage no higher than 36 volts. For a soldering iron supply voltage of 220 volts, rewinding the spiral will be much more difficult. A thin and long wire must be carefully wound (so that the turns do not have direct contact) around the base of the heater. For a beginner, this is difficult and time-consuming.

You can go another way. Repairing a burnt soldering iron involves replacing the entire heating element. For example, when the problem of a burnt soldering iron affected me, I went to the Aliexpress website, typed in “soldering iron heater” into the search, and then chose the most suitable option (in terms of size, power and supply voltage I needed). The cost of this heating element was quite low (when compared with buying a new electric soldering iron). Then I placed an order, paid, delivery took about 2 weeks.

Installing a new heating element on a burnt-out soldering iron was not difficult. It fit normally into the base of the soldering iron. Except that the old tip was slightly larger in size than the hole that was on the new heater. I simply took a piece of copper wire of the required length and diameter. One end of it (the one that will be soldered) was ground off at an angle. The heating element is fixed with one short screw on one side of the base of the soldering iron. The tip itself is fixed with another screw (slightly longer than the first) on the other side of the base.

The outgoing wires from the heating element were twisted with the wires of the power cord. Having previously put on them small pieces of polyvinyl chloride tube, which has heat-resistant properties. These pieces of tubes act as electrical insulators, which prevent short circuits from occurring at the junction of the wires. Conventional insulation in the form of electrical tape or shrink heat tube will not work, since it will simply collapse when the soldering iron heats up. You can also use fabric or fiberglass tape. That’s basically all the work involved in repairing a burnt-out soldering iron.

P.S. If we talk about what will be cheaper - repair or purchase of a new soldering iron, then repair by replacing a burnt heating element will still cost much less. Whether you can replace it yourself or not is another matter. When purchasing, pay attention to the dimensions of the new heating element, as even a small discrepancy may lead to additional adjustment steps. In addition, make sure that the power and voltage correspond to the values that you need.

An electric soldering iron is hand tool, intended for fastening parts together using soft solders. by heating the solder to a liquid state and filling the gap between the parts being soldered with it.

Electric soldering irons are produced designed for mains voltages of 12, 24, 36, 42 and 220 V, and there are reasons for this. The main thing is human safety, the second is the network voltage in the place soldering work. In production, where all equipment is grounded and there is high humidity, it is allowed to use soldering irons with a voltage of no more than 36 V, and the body of the soldering iron must be grounded. The motorcycle's on-board network has voltage direct current 6 V, a passenger car - 12 V, a truck - 24 V. In aviation, they use a network with a frequency of 400 Hz and a voltage of 27 V. There are also design restrictions, for example, a 12 W soldering iron is difficult to make for a supply voltage of 220 V, since the spiral will need to be wound made of very thin wire and therefore winding many layers, the soldering iron will turn out to be large, not convenient for small work. Since the soldering iron winding is wound from nichrome wire, it can be powered with either alternating or direct voltage. The main thing is that the supply voltage matches the voltage for which the soldering iron is designed.

Electric soldering irons come in power ratings of 12, 20, 40, 60, 100 W and more. And this is also no coincidence. In order for the solder to spread well over the surfaces of the parts being soldered during soldering, they need to be heated to a temperature slightly higher than the melting point of the solder. Upon contact with a part, heat is transferred from the tip to the part and the temperature of the tip drops. If the diameter of the soldering iron tip is not sufficient or the power of the heating element is small, then, having given off heat, the tip will not be able to heat up to the set temperature, and soldering will be impossible. At best, the result will be loose and not strong soldering. A more powerful soldering iron can solder small parts, but there is a problem of inaccessibility to the soldering point. How, for example, to solder in printed circuit board a microcircuit with a leg pitch of 1.25 mm with a soldering iron tip measuring 5 mm? True, there is a way out: several turns of copper wire with a diameter of 1 mm are wound around such a sting and the end of this wire is soldered. But the bulkiness of the soldering iron makes the work practically impossible. There is one more limitation. At high power, the soldering iron will quickly heat up the element, and many radio components do not allow heating above 70˚C and therefore the permissible soldering time is no more than 3 seconds. These are diodes, transistors, microcircuits.

Soldering iron device

Knowing the supply voltage and measuring the resistance of any heating electrical appliance, such as a soldering iron or electric kettle. electric heater or electric iron. You can find out the power consumed by this household appliance. For example, the resistance of a 1.5 kW electric kettle will be 32.2 Ohms.

Table for determining the resistance of a nichrome spiral depending on the power and supply voltage of electrical devices, Ohm

Power consumption
soldering iron, W

Online calculator for calculating the resistance value based on power consumption

Supply voltage, V:

Table of dependence of linear resistance (one meter) of nichrome wire on its diameter

Diameter of nichrome wire, mm

studvesna73.ru

Features of repairing and rewinding a soldering iron: rules for disassembling the device

A soldering iron is one of the most reliable tools, as it is a fairly simple device. But even these types of equipment can break down over time. Repairing a soldering iron is not a very difficult matter, but the main thing here is to determine the type of breakdown in order to fix it. Conventionally, everything can be divided into restoration of performance according to standard scheme, which is present in standard models, and fixes problems with additional tool functions. Indeed, some models have built-in temperature controllers, heating indicators and other things.

Repairing a soldering iron with your own hands is often not difficult, but in most cases people still prefer to buy new tools when it comes to simple budget models. However, if you want to save money, you can try to do everything yourself.

Common causes of breakdowns and ways to eliminate them

Before you figure out how to fix a soldering iron, it’s worth understanding what caused it to break. One of the most common reasons is a break electrical network. A rupture may occur in a section of the circuit, which will lead to the loss of the ability to warm up the instrument. The easiest way is if the circuit break occurs on the power cord. It is most susceptible to deformation and it is possible that sooner or later the wire will break. In this case, it is easier to completely replace the cord than to look for the break point.

Breaking the nichrome winding will require more complex procedures, although this is quite possible to do independently. First you need to find the break point. This can be done with a multimeter, but you will have to disassemble the soldering iron. This takes into account the winding resistance, which depends on the power of the tool. It can be viewed on the product body.

The reasons why the soldering iron coil burns out may lie in the following:

tool heating is too high;
voltage surges that lead to increased temperatures;
long continuous operation, increasing the temperature of the soldering iron;
winding defect when there is a wire problem areas, which fail first;
the presence of twists that increase resistance in a specific place.

How to properly disassemble a soldering iron?

For repairs, the body of the soldering iron is removed, which performs protective function. If the model has fixing rings, then they need to be moved apart. The protective casing is available in two main versions.

Soldering iron disassembled

To know how to disassemble a soldering iron, you need to study each of them:

on the pin with the winding there is a metal tube, which rests against the handle of the tool, and with reverse side clamped with a special end;
the body is made in the form of two halves of a tube, tapering at the edges (here both parts are fixed using clamping rings).

A simple way to troubleshoot problems

There are several ways to repair a soldering iron after disassembly. The simple method is as follows;

after removing the protective casing, the insulating layer is also removed;
when a break is detected, it is not at all necessary to bother yourself with a lengthy replacement of the entire winding;
it is enough to disconnect one end of it from the power terminal;
after that you just need to wind the wire from outside windings to the very place where the break is detected;
in the place of burnout you need to twist;
wind the wire;
the wire is connected to the power terminal;
the insulating winding is wound;
the case closes.

This is a simple method that is often used, but experts do not recommend it as the main one. The main disadvantage of this technique is that the resistance of the soldering iron at the twisting point increases. Accordingly, the temperature there rises during operation. It is the place of twisting that becomes the most dangerous for breakdowns in the future. There is a high probability that the wiring will burn out next time in the same place.

How to rewind a soldering iron?

So that after rewinding there is no residue left in the tool weak points, you need to rewind the entire reel on it. If it is necessary to preserve the characteristics of the model, then the parameters of the wire must be the same as the old one. In this case, it is necessary to maintain the number of turns that are provided in the design for each layer.

Rewinding a soldering iron with your own hands

The insulation can be replaced if it is not possible to choose the same exact option. Here you can use mica for a soldering iron in the form of plates or tubes, heat-resistant fiberglass or asbestos gaskets. Asbestos is one of the best insulators.

Mica for soldering iron with spiral

first an insulating layer is created;
then the first layer of winding is wound on it;
another insulating layer is applied to it;
a second layer of winding is wound on top of the second layer of insulation;
the remaining ends of the wire are mounted to the power cord.

It is necessary to maintain approximately the same number of turns in each layer of the winding. Thanks to this, it is possible to ensure uniform heating of the tool."

Sometimes problems arise with the insulating layers that are located between the windings. Here you also have to disassemble the tool and partially rewind it, but the main action is to replace the winding. The easiest way is to replace it with mica tubes. This material is an excellent dielectric and at the same time has the necessary thermal conductivity qualities. Mica is a rather fragile material, which becomes its main disadvantage. Even if the tubes are in a protected housing, there is a possibility of damage due to a mechanical shock. If the mica breaks down, the soldering iron may short out between the turns.

Safety precautions

During repairs, it is very important to follow safety precautions, as this will help keep the instrument in good condition and also protect the health and life of the technician. The basic rules include:

during all repair work and disassembly of the case, the soldering iron must be disconnected from the network;
if a breakdown occurs during operation, then in addition to de-energizing the tool, you need to wait until it cools down;
It is always worth remembering to create insulation and check its integrity so that a turn short circuit does not form after rewinding;
you should avoid creating twists both inside the tool and on the power cable, which potentially creates dangerous places during operation;
during a test run during repairs, it is better not to hold the soldering iron in your hands or be in close proximity to it;
The test switch-on must always be carried out and must wait until the instrument is completely warmed up.

Conclusion

Despite the fact that a soldering iron is an inexpensive tool, sometimes it is easier and cheaper to repair it than to buy a new one. The simplicity of the design reduces all repair operations to a few basic points, regardless of the cause of the problem. Repairing a Chinese soldering iron with a temperature controller will not be fundamentally different from restoring the functionality of a domestic tool without additional functions, unless we are talking about a breakdown of the temperature controller itself.

svarkaipayka.ru

Electric soldering iron - do-it-yourself device and repair

An electric soldering iron is a hand-held tool designed for fastening parts together using soft solders, by heating the solder to a liquid state and filling the gap between the parts being soldered with it.

Electrical circuit of a soldering iron

As you can see in the drawing electrical diagram The soldering iron is very simple, and consists of only three elements: a plug, a flexible electrical wire and a nichrome spiral.

As can be seen from the diagram, the soldering iron does not have the ability to adjust the heating temperature of the tip. And even if the power of the soldering iron is chosen correctly, it is still not a fact that the temperature of the tip will be required for soldering, since the length of the tip decreases over time due to its constant refilling; solders also have different temperatures melting. Therefore, in order to maintain the optimal temperature of the soldering iron tip, it is necessary to connect it through thyristor power regulators with manual adjustment and automatic maintenance of the set temperature of the soldering iron tip.

Soldering iron device

The soldering iron is a red copper rod, which is heated by a nichrome spiral to the melting temperature of the solder. The soldering iron rod is made of copper due to its high thermal conductivity. After all, when soldering, you need to quickly transfer heat from the soldering iron tip from the heating element. The end of the rod is wedge-shaped, is the working part of the soldering iron and is called the tip. The rod is inserted into a steel tube wrapped in mica or fiberglass. A nichrome wire is wound around the mica, which serves as a heating element.

A layer of mica or asbestos is wound over the nichrome, which serves to reduce heat loss and electrically insulate the nichrome spiral from the metal body of the soldering iron.

The ends of the nichrome spiral are connected to the copper conductors of an electrical cord with a plug at the end. To ensure the reliability of this connection, the ends of the nichrome spiral are bent and folded in half, which reduces heating at the junction with the copper wire. In addition, the connection is crimped with a metal plate; it is best to make the crimp from an aluminum plate, which has high thermal conductivity and will more effectively remove heat from the joint. For electrical insulation, tubes made of heat-resistant insulating material, fiberglass or mica are placed at the junction.

The copper rod and nichrome spiral are closed with a metal case consisting of two halves or a solid tube, as in the photo. The body of the soldering iron is fixed on the tube with cap rings. To protect a person’s hand from burns, a handle made of a material that does not transmit heat well, wood or heat-resistant plastic, is attached to the tube.

When inserting the soldering iron plug into the outlet electricity goes to a nichrome heating element, which heats up and transfers heat to the copper rod. The soldering iron is ready for soldering.

Low-power transistors, diodes, resistors, capacitors, microcircuits and thin wires are soldered with a 12 W soldering iron. Soldering irons 40 and 60 W are used for soldering powerful and large-sized radio components, thick wires and small parts. To solder large parts, for example, heat exchangers of a geyser, you will need a soldering iron with a power of one hundred or more watts.

Soldering iron supply voltage

There are also design limitations, for example, it is difficult to make a 12 W soldering iron with a supply voltage of 220 V, since the spiral will need to be wound from a very thin wire and therefore many layers will be wound; the soldering iron will turn out to be large and not convenient for small work. Since the soldering iron winding is wound from nichrome wire, it can be powered with either alternating or direct voltage. The main thing is that the supply voltage matches the voltage for which the soldering iron is designed.

Soldering iron heating power

A more powerful soldering iron can solder small parts, but there is a problem of inaccessibility to the soldering point. How, for example, can you solder a microcircuit with a leg pitch of 1.25 mm into a printed circuit board with a soldering iron tip measuring 5 mm? True, there is a way out: several turns of copper wire with a diameter of 1 mm are wound around such a sting and the end of this wire is soldered. But the bulkiness of the soldering iron makes the work practically impossible. There is one more limitation. At high power, the soldering iron will quickly heat up the element, and many radio components do not allow heating above 70˚C and therefore the permissible soldering time is no more than 3 seconds. These are diodes, transistors, microcircuits.

Calculation and repair of the heating winding of a soldering iron

When repairing or making your own electric soldering iron or any other heating device, you have to wind a heating winding made of nichrome wire. The initial data for calculating and selecting wire is the winding resistance of a soldering iron or heating device, which is determined based on its power and supply voltage. You can calculate what the winding resistance of a soldering iron or heating device should be using the table.

Knowing the supply voltage and measuring the resistance of any heating electrical appliance, such as a soldering iron, electric kettle, electric heater or electric iron, you can find out the power consumed by this household electrical appliance. For example, the resistance of a 1.5 kW electric kettle will be 32.2 Ohms.

Let's look at an example of how to use the table. Let's say you need to rewind a 60 W soldering iron designed for a supply voltage of 220 V. In the leftmost column of the table, select 60 W. From the top horizontal line, select 220 V. As a result of the calculation, it turns out that the resistance of the soldering iron winding, regardless of the winding material, should be equal to 806 Ohms.

If you needed to make a soldering iron from a 60 W soldering iron, designed for a voltage of 220 V, for power supply from a 36 V network, then the resistance of the new winding should already be equal to 22 Ohms. You can independently calculate the winding resistance of any electric heating device using an online calculator.

After determining the required resistance value of the soldering iron winding, the appropriate diameter of the nichrome wire is selected from the table below, based on the geometric dimensions of the winding. Nichrome wire is a chromium-nickel alloy that can withstand heating temperatures up to 1000˚C and is marked X20N80. This means that the alloy contains 20% chromium and 80% nickel.

To wind a soldering iron spiral with a resistance of 806 Ohms from the example above, you will need 5.75 meters of nichrome wire with a diameter of 0.1 mm (you need to divide 806 by 140), or 25.4 m of wire with a diameter of 0.2 mm, and so on.

I note that when heated by every 100°, the resistance of nichrome increases by 2%. Therefore, the resistance of the 806 Ohm spiral from the above example, when heated to 320˚C, will increase to 854 Ohms, which will have virtually no effect on the operation of the soldering iron.

When winding a soldering iron spiral, the turns are laid close to each other. When heated red-hot, the surface of the nichrome wire oxidizes and forms an insulating surface. If the entire length of the wire does not fit on the sleeve in one layer, then the wound layer is covered with mica and a second one is wound.

For electrical and thermal insulation of heating element windings the best materials is mica, fiberglass cloth and asbestos. Asbestos has an interesting property: it can be soaked with water and it becomes soft, allows you to give it any shape, and after drying it has sufficient mechanical strength. When insulating the winding of a soldering iron with wet asbestos, it is necessary to take into account that wet asbestos conducts electric current well and it will be possible to turn on the soldering iron into the electrical network only after the asbestos has completely dried.

ydoma.info

Principle of operation, main malfunctions and methods of repairing a soldering iron

Soldering devices of various types are widely used at industrial facilities, in radio equipment repair shops and household appliances, in domestic conditions. Depending on the operating conditions and purpose, there are many types of soldering equipment.

Electric soldering iron with spiral heating

Applications and types

Electric soldering iron alternating current with spiral heating of the core, it operates from a standard power supply network for household equipment at 220V 50-60Hz.
A cordless electric soldering iron is used for desoldering wires and other small-sized elements where high power up to 15 W is not required;
There are varieties of gas soldering irons that are used for strong heating of metal elements and refractory alloys;
To work with low-melting tin during the installation and repair of radio equipment, pistol-type soldering irons with pulsed voltage supply are widely used. When you press the trigger, the tip of the soldering iron heats up; after soldering is completed, the trigger is released and the heating element cools down;
Soldering irons with ceramic rods have a long service life and allow you to select the desired temperature mode and power consumption;

Soldering iron with ceramic tips on the rod

Induction soldering irons are widely used. An inductive coil creates a magnetic field on the ferromagnetic tip, which heats the core. If lost magnetic properties the core stops heating, this is a significant drawback of such models.

An electric soldering iron is used as a hand tool. With its help, solder is melted to a liquid state, which fills the cracks and irregularities of heated metal elements at the joints, for which alloys of low-melting metals are used:

tin;
lead;
zinc;
nickel;
copper and others.

The melting temperature of solders must be less than the melting temperature of the metal elements being connected.

The industry produces different types of soldering irons. The most commonly used in industry and at the household level are spiral soldering irons, which are worth describing in more detail.

Soldering iron design and operating principle

One of the main elements of a soldering iron is a heating rod on which nichrome wire is wound in a spiral. In order to retain heat longer, the rod is inserted into a steel cylinder, which is insulated with heat-resistant fiberglass, mica or asbestos layer. A winding of nichrome wire is wound onto this dielectric layer. These measures exclude short circuit between turns.

Depending on the power of the soldering iron, the winding can be multilayer: fiberglass - winding - fiberglass - continuation of the spiral.

How more power soldering iron, the more turns of the spiral, the thinner the diameter of the wire. For high thermal conductivity of the rod, red copper is used, thus achieving rapid heating and heat transfer to the soldering iron tip.

Schematic diagram of a spiral soldering iron

List of main elements:

plug and cord for connecting to the power supply;
holder;
wooden handle, can be made of heat-resistant plastic;
copper rod;
dielectric gaskets;
heating coil;
protective casing of the spiral with fixing rings.

The electrical circuit of the soldering iron is simple and consists of three elements:

power supply;
plug with wire;
wire heating coil.

Electrical circuit of a soldering iron

An electric current passing through a spiral of nichrome wire heats up the winding, and the heat is transferred to the core and soldering iron tip.

Malfunctions and their elimination

The most common fault with soldering irons of this model is an open circuit. If there is a break in a section of the electrical cord, repairing the soldering iron is simple - just replacing the cord or plug. In the event of a break in the nichrome winding, repairs are more complicated, but are possible with your own hands.

Nichrome winding of an electric soldering iron

To determine the break and repair the winding, the easiest way is to use a multimeter, taking into account the winding resistance, which depends on the power and is indicated on the soldering iron body or in the product data sheet.

It is necessary to move apart the fixing rings and remove the protective housing of the soldering iron winding. The protection casing comes in two versions. A metal tube, which fits onto a pin with a winding and rests against the handle, is secured on the tip side with a clamping ring. The second option is when the protective housing consists of two longitudinal halves of a tube with a decreasing diameter at the edges, where the two components are fixed with clamping rings.

When doing DIY repairs, some amateur craftsmen remove the protective cover and upper layer Winding insulation, having discovered a break, does not bother themselves with the labor-intensive replacement of the wire of the entire winding. Disconnect the end from the terminal on the power cord, and wind the wire from the outside of the winding until it breaks. Then they make a careful twist at the burnout site, wind the wire, connect it back to the power cord terminal, and attach the outer layer of insulation. They put on a protective case, plug in the soldering iron and it works properly.

This DIY repair method is possible, but not recommended. The disadvantage of this method is that in the place of twisting the heating of the nichrome wire will be greater than in other parts of the chain. Ultimately, the operation of such a soldering iron will be short-lived. The winding will burn out in the same place. For reliable operation you'll have to rewind the whole reel.

If you need to achieve the same heating power, you need to wind a new coil with the same wire, with the same number of turns in each layer.

Different materials are used to insulate the winding layers:

asbestos gaskets;
heat-resistant fiberglass;
mica tubes or plates.

Asbestos is considered the most practical; the plate can be soaked with water, after which it becomes elastic and takes on any shape that you mold with your own hands. The first layer of spiral is wound onto the dried coating, then the second layer of asbestos and the continuation of the winding, until the end of the wire.

The number of turns in each layer and the thickness of the insulation should be approximately the same. This condition ensures uniform heating. The remaining ends of the winding are connected to the power cord.

Connecting the winding to the power cord

To repair the insulating layer of the winding, mica tubes and plates are used, which have high thermal conductivity and are a reliable dielectric. The disadvantage of this material is its fragility - it is difficult to install, sometimes mica crumbles right in your hands.

With mechanical impacts on the protective housing of the winding, the mica plates may collapse, which will lead to an interturn short circuit in the spiral.

The soldering iron tip is sharpened to a cone for convenient soldering of small elements. During operation, it requires periodic editing with a file.

Electric soldering iron tip shape

When winding a new coil at the calculated power, there is no absolute certainty that the rod will heat the elements that need to be soldered and the solder to a liquid state. It depends on the tip, the new one is larger, and with use it decreases. Solders also have different temperatures melting.

All these factors influence the heating time and temperature to achieve the desired power consumption and temperature parameters. The soldering iron is turned on through a thyristor power regulator. This device allows you to automatically maintain desired temperature rod.

Calculation of required parameters

In order to repair a failed soldering iron, you can change its parameters, taking into account the intended purpose, i.e. what do you use a soldering iron for (soldering a pan or a microcircuit). In this case, special tables are used, where the following values are specified for selection:

consumed electric power soldering iron;
supply voltage;
resistance of nichrome wire.

Required spiral resistance for different meanings power and voltage are pre-calculated and tabulated.

Selecting the resistance of the spiral (nichrome wire) according to the power and voltage of the soldering iron Ohm

Power, watts	Voltage, Volts
	12	24	36	127	220
12	12	48,0	108	1344	4033
24	6,0	24,0	54	672	2016
36	4,0	16,0	36	448	1344
42	3,4	13,7	31	384	1152
60	2,4	9,6	22	269	806
75	1,9	7,7	17	215	645
100	1,4	5,7	13	161	484

To rewind a soldering iron with a power of 36 W at a supply voltage of 220V, the table shows that the winding resistance should be 1344 Ohms. Next, you can take the existing wire, attach the Ohmmeter terminal to the end, move the second terminal along the unwound wire until it reads 1334 Ohm. At this mark, cut off the measured section and wind it onto the soldering iron coil.

Resistance of a meter nichrome wire to its diameter

Dia- meter, mm	1,0	0,9	0,8	0,7	0,6	0,5	0,4	0,3	0,2	0,1	0,08	0,07
Ohm/m	1,4	1,7	2,2	2,89	3,93	5,6	8,75	15,7	34,6	137	208	280

You can use the above table. Measure the diameter of the wire with a micrometer and use the table to determine the required length of wire in the coil. So, if the wire diameter is 0.08 mm, the resistance per meter will be 208 Ohms. The required resistance is 1334 Ohm / 208 Ohm = 6.4 m. This results in the length of the wire that should be wound on the coil.

The turns on the winding are laid closely, heating up red-hot, the scale of the nichrome coating forms an insulating interturn layer. When the length of the coil is not enough, an insulating layer, fiberglass, asbestos or mica is applied, and a second layer is wound. Almost every coil consists of several layers ,

An electric soldering iron is a hand-held equipment that allows you to use soft solders to connect parts together, heating the solder to a liquid consistency, filling the voids between the elements being connected. Before purchasing a tool, you need to familiarize yourself with the technical characteristics of the device, operating instructions and how to repair a soldering iron.

A soldering iron is a tool necessary for performing minor repairs on electronic devices.

terms of Use

When making your own soldering iron, a thin wire is used to wind the spiral. The supply and tool voltages must match each other. The power of such units reaches from 12 to 100 W and higher, because it is possible to ensure that the solder spreads evenly over the surface of the elements being connected if they are heated above its melting point. Heat from the tip is transferred to the parts upon contact, because of this the temperature of the tip decreases.

Insufficient power of the heating coil or small diameter of the rod may prevent the tip from heating to the required temperature, which prevents soldering. Powerful soldering irons can be used to connect small parts, but due to the size of the device, access to the soldered elements is limited. Experts recommend winding a copper wire with a diameter of 1 mm around the tip. The high power of such devices allows you to quickly warm up the elements, and most small radio components, transistors, diodes, microcircuits cannot withstand temperatures exceeding 70 ° C. Soldering time is reduced to 3 seconds. Before you repair the device in question, you will need to find out its design features.

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Components

The tip is the working part of the tool, a rod with a wedge-shaped tip. It is inserted into a steel tube wrapped in fiberglass cloth or mica, on which a wire is wound, which acts as a heating element. Nichrome wire is wrapped with asbestos, which helps reduce heat loss. The ends of a nichrome spiral are attached to the conductors of the electrical cord with a plug, which are bent and folded in half to ensure greater reliability and reduce the heating temperature at the points of connection with the copper wire. The connection is additionally crimped with a metal plate.

The quality of work cannot be guaranteed by selecting the correct power tool. Incorrect operation of the unit leads to breakdown and the need to repair the soldering iron.

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Step-by-step instruction

Independent production or repair of heating devices is carried out taking into account the calculation of the resistance of the heating element or winding. Knowing the voltage and resistance values of an electrical appliance allows you to calculate its power that it consumes. The resistance in the winding of a 60 W soldering iron, powered by a 36 V network, should reach 22 Ohms. Correct selection of power and voltage helps to avoid breakdown and the need to repair the device in question.

Schemes of temperature controllers for the soldering iron tip.

Then you need to select the diameter of the nichrome wire, comparable to the dimensions of the winding. The spiral winding with a resistance of 806 Ohms is performed using 5.75 m of wire with a diameter of 0.1 mm (the resistance value is divided by 140) or 25.4 m of wire with a diameter of 0.2 mm. The coils must be laid closely. The surface of the nichrome wire will oxidize when heated, creating an insulating surface. The wound layer, which does not fit into the first row, is covered with mica. Wind up the second row. High-quality assembly allows you to operate the tool for a long time without breakdowns or repairs.

The main cause of soldering iron malfunction is a broken heating element.

Simple repairs help restore its functionality. To repair a soldering iron, you will need the following tools:

pliers;
sharp knife;
ceramic resistance “PEV-10”;
asbestos thread.

The faulty heating element is then removed. A prepared ceramic resistor is placed in the resulting socket. The next step is to connect the power wires to the resistor. To do this, it is recommended to use the channels in the handle of the device. The wires must be laid so that they do not come into contact with the housing, and the terminals must be insulated with asbestos thread. Upon completion of the repair work, you will need to assemble the components of the soldering iron in the reverse order. To repair a soldering iron yourself, you will need its circuit diagram.

Soldering devices of various types are widely used at industrial facilities, in workshops for repairing radio equipment and household appliances, and in domestic conditions. Depending on the operating conditions and purpose, there are many types of soldering equipment.

Electric soldering iron with spiral heating

Applications and types

The AC electric soldering iron with spiral heating of the core operates from a standard power supply network for household equipment at 220V 50-60Hz.
A cordless electric soldering iron is used for desoldering wires and other small-sized elements where high power up to 15 W is not required;
There are varieties of gas soldering irons that are used for strong heating of metal elements and refractory alloys;
To work with low-melting tin during the installation and repair of radio equipment, pistol-type soldering irons with pulsed voltage supply are widely used. When you press the trigger, the tip of the soldering iron heats up; after soldering is completed, the trigger is released and the heating element cools down;
Soldering irons with ceramic rods have a long service life and allow you to select the desired temperature mode and power consumption;

Soldering iron with ceramic tips on the rod

Induction soldering irons are widely used. An inductive coil creates a magnetic field on the ferromagnetic tip, which heats the core. When the magnetic properties of the core are lost, heating stops; this is a significant drawback of such models.

tin;
lead;
zinc;
nickel;
copper and others.

The melting temperature of solders must be less than the melting temperature of the metal elements being connected.

The industry produces different types of soldering irons. The most commonly used in industry and at the household level are spiral soldering irons, which are worth describing in more detail.

Soldering iron design and operating principle

Depending on the power of the soldering iron, the winding can be multilayer: fiberglass - winding - fiberglass - continuation of the spiral.

The greater the power of the soldering iron, the more turns of the spiral, the thinner the diameter of the wire. For high thermal conductivity of the rod, red copper is used, thus achieving rapid heating and heat transfer to the soldering iron tip.

Schematic diagram of a spiral soldering iron

List of main elements:

plug and cord for connecting to the power supply;
holder;
wooden handle, can be made of heat-resistant plastic;
copper rod;
dielectric gaskets;
heating coil;
protective casing of the spiral with fixing rings.

The electrical circuit of the soldering iron is simple and consists of three elements:

power supply;
plug with wire;
wire heating coil.

Electrical circuit of a soldering iron

An electric current passing through a spiral of nichrome wire heats up the winding, and the heat is transferred to the core and soldering iron tip.

Malfunctions and their elimination

Nichrome winding of an electric soldering iron

When making repairs with their own hands, some amateur craftsmen, after removing the protective casing and the top layer of winding insulation, discover a break, do not bother themselves with the labor-intensive replacement of the wire of the entire winding. Disconnect the end from the terminal on the power cord, and wind the wire from the outside of the winding until it breaks. Then they make a careful twist at the burnout site, wind the wire, connect it back to the power cord terminal, and attach the outer layer of insulation. They put on a protective case, plug in the soldering iron and it works properly.

If you need to achieve the same heating power, you need to wind a new coil with the same wire, with the same number of turns in each layer.

Different materials are used to insulate the winding layers:

asbestos gaskets;
heat-resistant fiberglass;
mica tubes or plates.

Connecting the winding to the power cord

With mechanical impacts on the protective housing of the winding, the mica plates may collapse, which will lead to an interturn short circuit in the spiral.

The soldering iron tip is sharpened to a cone for convenient soldering of small elements. During operation, it requires periodic editing with a file.

Electric soldering iron tip shape

Calculation of required parameters

soldering iron power consumption;
supply voltage;
resistance of nichrome wire.

The required coil resistance for various power and voltage values is pre-calculated and tabulated.

Selecting the resistance of the spiral (nichrome wire) according to the power and voltage of the soldering iron Ohm

Power, watts	Voltage, Volts
	12	24	36	127	220
12	12	48,0	108	1344	4033
24	6,0	24,0	54	672	2016
36	4,0	16,0	36	448	1344
42	3,4	13,7	31	384	1152
60	2,4	9,6	22	269	806
75	1,9	7,7	17	215	645
100	1,4	5,7	13	161	484

Resistance of a meter nichrome wire to its diameter

Dia- meter, mm	1,0	0,9	0,8	0,7	0,6	0,5	0,4	0,3	0,2	0,1	0,08	0,07
Ohm/m	1,4	1,7	2,2	2,89	3,93	5,6	8,75	15,7	34,6	137	208	280

Video about repairs

How to repair a soldering iron and rewind it to 12 Volts is described in the video below.

From the above information it follows that having certain skills, tools, materials and knowledge in electrical engineering, repairing a soldering iron with your own hands is not a big problem.

I decided to rewind a burnt out 40-watt soldering iron. And why not, if all the materials are there?
But rewound to 220 V. burned out the first time it was turned on due to the emitted fumes at a voltage of 150 V. Because when rewinding I used fiberglass adhesive tape. Therefore, it is necessary to use insulating materials that are free from flammable substances or anneal them.
And first turn it on at low voltages, increasing it to 220 V. as the smoke stops. For example, for a soldering iron 40W. through light bulbs 15,25,40 W.
I have to suffer again, winding a 220V winding with a thin wire. I didn't feel like it anymore.
I took nichrome from a hair dryer and wrapped two layers. It turned out to be 30V, 1.1A.
Then I got an electronic transformer for 12V, which might be suitable
To power the soldering iron in one layer, but the soldering iron was already ready.
Basic materials for rewinding:
Mica. Taken from a mica capacitor big size type KSO13.
Nichrome. From a hair dryer.
Step-down transformer and graphite rod from a battery for welding nichrome with copper wire.
Asbestos cord for thermal insulation.
Auto sealant black. Withstands temperatures up to 300 degrees.
Metal braid. For small soldering irons, braid from connecting hoses for toilets, boilers, etc. may be suitable... But it is very soft, maybe in two layers.
For 40W. A stiffer braid is better. From high pressure hoses, brake hoses, etc.
MGTF wire. To rewind the transformer and for the soldering iron, I used it with an outer insulation diameter of 0.7 mm. For welding two pieces of wire with a diameter of 2 mm insulation to nichrome.
We wrap mica around the winding area and secure it with several turns of thin thread.
Before winding, we weld one section with nichrome (if you don’t have experience, read it on the Internet, then practice), isolate the junction and insert the handles into the tube. I fix the first turn by winding the next two turns around it. Don’t forget that after the inserted leads you need space to attach the outer braid, about 1 cm. and from the end the same way. I fix the last turn by wrapping it several times with thin nichrome. We insert the second piece of thick wire into the handle, twist it tightly with nichrome, weld it, and insulate it. The leads of the wire sections from the handle must be firmly fixed so as not to accidentally pull out the turns. At least firmly insert a piece of wood with glue into the handle.
Now you can connect to a step-down transformer or to a power supply of appropriate power with an adjustable output voltage for testing normal operation heating winding and approximately determining the voltage and current at which it will operate.
After cooling, we wrap a layer of mica and then asbestos cord. The cord, unlike sheet cord, does not crumble and lies more tightly. Anyone concerned about asbestos can look for a replacement. Some kind of fiberglass cord or material.
Check that the tightened braid fits onto the cord. Lubricate with auto sealant and put on the braid. Using the same nichrome, we wrap the edge of the braid on the side of the handle, after which we stretch, compact the braid and wrap it to the tube from the front. Unravel and cut with wire cutters unnecessary part braids. While the sealant hardens, we assemble a soft cord that will not melt from the soldering iron tip. Since there was a wire in fluoroplastic insulation with an insulation diameter of approximately 0.7 mm, I used it. I took 6 wires, braided them - it turned out to be a soft, strong cable. We solder it to the leads from the soldering iron, and attach the solders to the handle with electrical tape. This makes it easy to re-solder the cable if it breaks near the handle.
Lightweight and small-sized electronic transformers for halogen lamps have given rise to their use to power low-voltage soldering irons.
I got it at 160W. with broken 12-amp transistors 13009. Since such power is unnecessary, I replaced them with the existing 4-amp 13005. Instead of 8 turns of the busbar for 12 V, I wound 45 turns with a tap from 39. The installed switch connects the soldering iron
To 39 turns - for soldering small items without overheating or to 45 turns. The output transformer is installed on the board using silicone with a gap of about 1mm to the board. If necessary, excess turns can be easily removed. If you install the soldering iron power switch inside the case, you may have to install the transformer by moving it to one side. An LED indicator with a diode and a resistor is installed in the center of the output. transformer, connecting it to the last turns.
The power plug can be attached to the case by cutting it off from similar devices, for example, wall power supplies, cell phone chargers. You can also attach a plug on a short cable, it is more convenient to connect to tees.
When turned on for the first time, the electronic transformer did not work. Low load. Since the load is constant and short-circuit. It’s not foreseen that without bothering with alterations to the OS voltage, I added a turn to the existing turn of the current winding on a small ring, and it worked.
What is written here is the general direction. Everyone will have their own path depending on the components they have.

As you can see in the drawing, the electrical circuit of the soldering iron is very simple, and consists of only three elements: a plug, a flexible electrical wire and a nichrome spiral.

As can be seen from the diagram, the soldering iron does not have the ability to adjust the heating temperature of the tip. And even if the power of the soldering iron is chosen correctly, it is still not a fact that the temperature of the tip will be required for soldering, since the length of the tip decreases over time due to its constant refilling; solders also have different melting temperatures. Therefore, in order to maintain the optimal temperature of the soldering iron tip, it is necessary to connect it through thyristor power regulators with manual adjustment and automatic maintenance of the set temperature of the soldering iron tip.

Soldering iron device

A layer of mica or asbestos is wound over the nichrome, which serves to reduce heat loss and electrically insulate the nichrome spiral from the metal body of the soldering iron.

When you insert the soldering iron plug into a socket, electric current flows to the nichrome heating element, which heats up and transfers heat to the copper rod. The soldering iron is ready for soldering.

Soldering iron supply voltage

Soldering iron heating power

DIY soldering iron repair

The soldering iron stops heating for one of two reasons. This is a result of chafing of the power cord or burnout of the heating coil. Most often the cord frays.

Checking the serviceability of the power cord and soldering iron coil

When soldering, the power cord of the soldering iron is constantly bent, especially strongly at the point where it exits and the plug. Usually in these places, especially if the power cord is hard, it frays. This malfunction first manifests itself as insufficient heating of the soldering iron or periodic cooling of it. Eventually, the soldering iron stops heating.

Therefore, before repairing the soldering iron, you need to check the presence of supply voltage in the outlet. If there is voltage in the outlet, check the power cord. Sometimes a faulty cord can be determined by gently bending it where it exits the plug and soldering iron. If the soldering iron becomes a little warmer, then the cord is definitely faulty.

You can check the serviceability of the cord by connecting the probes of a multimeter turned on in resistance measurement mode to the pins of the plug. If the readings change when bending the cord, the cord is frayed.

If it is discovered that the cord is broken at the point where it exits the plug, then to repair the soldering iron it will be enough to cut off part of the cord along with the plug and install a collapsible one on the cord.

If the cord is frayed at the point where it exits the soldering iron handle or the multimeter connected to the pins of the plug does not show resistance when bending the cord, then you will have to disassemble the soldering iron. To gain access to the place where the spiral is connected to the cord wires, it will be enough to remove only the handle. Next, touch the multimeter probes successively to the contacts and pins of the plug. If the resistance is zero, then the spiral is broken or its contact with the cord wires is poor.

Calculation and repair of the heating winding of a soldering iron

Table for determining the resistance of a nichrome spiral depending on the power and supply voltage of electrical devices, Ohm
Power consumption soldering iron, W	Soldering iron supply voltage, V
Power consumption soldering iron, W	12	24	36	127	220
12	12	48,0	108	1344	4033
24	6,0	24,0	54	672	2016
36	4,0	16,0	36	448	1344
42	3,4	13,7	31	384	1152
60	2,4	9,6	22	269	806
75	1.9	7.7	17	215	645
100	1,4	5,7	13	161	484
150	0,96	3,84	8,6	107	332
200	0,72	2,88	6,5	80,6	242
300	0,48	1,92	4,3	53,8	161
400	0,36	1,44	3,2	40,3	121
500	0,29	1,15	2,6	32,3	96,8
700	0,21	0,83	1,85	23,0	69,1
900	0,16	0,64	1,44	17,9	53,8
1000	0,14	0,57	1,30	16,1	48,4
1500	0,10	0,38	0,86	10,8	32,3
2000	0,07	0,29	0,65	8,06	24,2
2500	0,06	0,23	0,52	6,45	19,4
3000	0,05	0,19	0,43	5,38	16,1

For electrical and thermal insulation of the heating element winding, the best materials are mica, fiberglass cloth and asbestos. Asbestos has an interesting property: it can be soaked with water and it becomes soft, allows you to give it any shape, and after drying it has sufficient mechanical strength. When insulating the winding of a soldering iron with wet asbestos, it is necessary to take into account that wet asbestos conducts electric current well and it will be possible to turn on the soldering iron into the electrical network only after the asbestos has completely dried.