Everything about the rules for using an electric soldering iron and how to repair it yourself. Calculation and repair of the heating winding of a soldering iron. What is the resistance of a soldering iron?

DIY ceramic heating element

The most common reason failure of an electric soldering iron is a burnt-out spiral heating element. Even if you have nichrome wire of a suitable diameter and length, it is practically impossible to wind a new spiral (for a soldering iron designed for a voltage of 220 volts exactly), the turns of the spiral must be too close to each other in order to fit the required amount. Such winding is only possible with special equipment. And let's look at how to make a heating element for a soldering iron with your own hands.

I don’t take into account individual enthusiasts who succeeded. As for soldering irons designed for voltages of 110 volts and below (for example, in soldering stations), then everything is becoming more realistic. The required resistance of the heating element (nichrome) is much lower and, accordingly, the length of the wire that must be wound properly is much less.

But there is also an insulating dielectric called mica, which is inherently “touchless” - it crumbles and crumbles even with the most gentle handling. In short, I wasn’t going to do any more repairing soldering irons and suddenly I found information that mica can be perfectly replaced by a tandem consisting of the most common talc and office glue, which form protective coating similar to ceramic. I tried it and it worked.

To make a miniature heating element, you need: nichrome with a diameter of up to 0.1 mm, thin (slightly thicker than nichrome) non-elastic steel wire, asbestos thread and the thinnest sewing needle inserted into the marking object of a drawing set called a “ready box”. The first step is to firmly and compactly connect the ends of the nichrome and steel wire twisting method.

Now you need to assemble the presented circuit. It will help you decide on the length nichrome wire, from which the heating coil should be wound.

When everything is connected, gradually increase the voltage, look at the readings of the power supply voltmeter and ammeter. IN in this case at a voltage of 11 volts, the current consumption was almost 0.5 A. Multiplying these indicators, we obtain the approximate power of the future heating element - 5.5 W. The coil has not yet warmed up to red (at full power) and there is no need to burn it, it is already clear that it will be possible to supply 12 or even 13 volts to it when the heating element is ready. So the desired power of 8 W will be easily achieved. Finally, the resistance of the section of nichrome wire to which voltage was applied is measured - for comparable control of the length when winding the spiral.

To begin the winding process, a steel wire is threaded into the same “eye” as a needle, onto which an asbestos thread is mounted, designed to act as a mandrel for winding the spiral and at the same time as the base of the future heating element. Important - before starting winding, the junction of the nichrome and steel wire must be located at at least, a few millimeters (2 - 3 mm) from the edge of the asbestos thread towards its middle (it got lost in the top photo, I corrected it before winding). It’s better to wind it a little more; when the needle is pulled out, you can easily unwind the excess, but you won’t be able to wind it too much. The spiral on the asbestos thread removed from the needle is measured to determine the resistance and adjusted to what is required.

Next you will need talc and office (silicate) glue. The most non-specific action awaits, because the method of applying the protective layer (full dielectric in the future, after drying) can, in principle, be different.

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Construction and repair of an electric soldering iron

An electric soldering iron is hand tool, intended for fastening parts together using soft solders, by heating the solder to liquid state and filling the gap between the soldered parts 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, to maintain optimal temperature soldering iron tips have to be connected through thyristor power regulators with manual adjustment and automatic maintenance the set temperature of the soldering iron tip.

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 copper conductors 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 electric current 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

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 at the place where the soldering work is performed. 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 DC 6 V, passenger car– 12 V, cargo – 24 V. In aviation they use a network with a frequency of 400 Hz and a voltage of 27 V.

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

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 the problem arises 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 are wound around such a sting. copper wire with a diameter of 1 mm 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

During repairs or self-production An electric soldering iron or any other heating device requires winding 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 it household electrical appliance power. 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 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 electrical 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

Repairing a burnt soldering iron (for soldering parts), replacing the heating element with your own hands.

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(by size, by the power I need and supply voltage). 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, as 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.

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.

What you need to remake a soldering iron

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

Refinement of the Chinese soldering iron

The first thing we will pay attention to is the ineffective tip; we will replace it with a 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.

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.

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.

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.

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

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 at the place where the soldering work is performed. 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 on-board network of a motorcycle has a DC voltage of 6 V, a passenger car - 12 V, a truck - 24 V. In aviation, a network with a frequency of 400 Hz and a voltage of 27 V is used.

Soldering iron heating power

A more powerful soldering iron can solder small parts, but the problem arises 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.

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

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.

Table for determining the resistance of a nichrome spiral depending on power and supply voltage electrical appliances, 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 electrical current well and it will be possible to turn on the soldering iron into the electrical network only after the asbestos has completely dried.

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 one. 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 two screws connecting the protective casing to the 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. There is a slot in the mica on the side of the tip into which a conductor is inserted, running from the nichrome to the power cable - therefore, the weakened mica wrapper is removed from it rather than unwound. 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 reel in mandatory for something round ideal option- spool for thread. 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 ( total length 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 I managed to reel required quantity 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).

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.

Tests

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.

Heating rate

Finally, a test for heating duration. Up to 257 degrees in 2 minutes 20 seconds. Excellent result, if we 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.

Let me remind you that we have in our hands a soldering iron with a torn off power cord. Tasks for the next half hour:

A) get acquainted with internal structure hero of the review;
b) if possible, bring him back to life.

The first thing we do is remove the handle made of heat-resistant plastic. What remains in your hands is – let’s call it that – a “casing”, in which all the patient’s insides are actually located.

We unscrew the only bolt - two or three turns allow you to fix or release the rod, which actually does the soldering, and its complete separation from the thread allows you to remove the “cartridge” for the rod.

On the other side of the “casing” we bend two antennae and first carefully take out two thin tubes about 4 cm long, metallic color, and behind them is the heating element itself - the same type of tube larger diameter and the length in which a spiral made of metal with high resistivity (most likely nichrome) is placed.

As you can see, the contacts of our spiral remained intact - great news. To ensure the integrity of the heating element, you can measure the resistance between the contacts. For a 25W soldering iron, it resists approximately 2kOhm +/-100Ohm.

Here's everything that any standard soldering iron consists of:

The next step is to connect the contacts of the spiral to the power cord. Don’t forget that you first need to “put” a soldering iron handle and a white cap onto the cord. heat shrink tube, and on each wire there are small tubes that serve to isolate one contact from the other

(although they look like metal, in fact they do not conduct current, they crumble easily and peel off. In addition, they are not afraid of high temperatures).

You can cheat - connect the wires somehow, but in this case it is possible that the patient will soon get sick again, so it’s better to overdo it.

It turns out? Then everything is just a matter of exposed wire We put on our insulating tubes, slide the white polyvinyl chloride heat-shrinkable tube closer, and place the whole thing in the “casing” of the heating element.

Since the rod holder and the rod itself have become fairly smoked during operation, I advise you to lightly clean them with fine sandpaper, and lightly flatten the “cartridge” to achieve better contact and heat transfer from one to another.

We place the cartridge with the rod in the “casing” on the other side and secure it with a screw.

Just in case, we check the resistance again, this time between the contacts of the power plug. It shouldn’t have changed, so if it increases, it means you have a bad connection somewhere. If the resistance is close to zero, you have managed to create a short circuit somewhere in this simple circuit. Neither the first option nor the second, of course, are suitable for any real testing and, especially, work. We disassemble the soldering iron again, correct the errors, and reassemble in the reverse order.
Is everything okay now? Okay, then you can bend the antennae of the “casing” of the heating element...

...and put a plastic handle on it.
Just in case, let's also check the resistance between the contacts of the power plug. Now the soldering iron can be plugged into the network with a confident hand. Particularly timid people can hide behind the sofa and turn on the soldering iron through a power extension cord or even a switch in the hallway :).
Everything _must_ work.
Personally, I succeeded. The whole thing took about half an hour. Got a boost of energy for the whole day folk craftsman– you can move to new heights!