With the advent of LED technology, lighting systems have taken to a whole new level. Economical, environmentally friendly and electrically safe devices are used everywhere today - they have replaced the standard "Ilyich lamps" and the "housekeepers" that have gained popularity. The former have long been outdated from a moral point of view, the latter are extremely hazardous to health due to the mercury vapor contained inside.
Despite the long service life, even such devices fail over time. In some situations, expensive repair of LED lamps can be done independently, at home, which we will consider further.
Before disassembling a failed LED lamp into its component parts, be sure to study its structure and principle of operation. Standard equipment of this type includes an electronic power supply board, a light filter and a housing with a base. Cheaper models use conventional capacitors instead of current and voltage limiters.
One lamp can have several dozen LEDs that are connected in series or in parallel. In the second case, the design turns out to be expensive (a separate resistor is connected to each led diode or group), so not everyone can afford it.
The principle of operation of an LED is almost identical to a semiconductor element. The current between the anode and cathode travels in a straight line, which leads to the formation of a glow.Each LED individually is characterized by a minimum power, which is why several pieces are used at once. To create the desired luminous flux, a phosphor coating is used, which transforms the light into a spectrum visible to the human eye.
High-quality models contain a high-tech driver that performs the function of a converter along with a diode group. The primary voltage goes to a transformer that reduces the characteristics of the current. At the output of the element, we get the constant current necessary to power the led diodes. In order to reduce ripple in the circuit, an auxiliary capacitor is used.
Despite the numerous varieties, differences in devices, the number of LEDs used, all lighting devices of this type are characterized by the same design, which simplifies their maintenance.
There are several possible malfunctions of LED devices, which is associated with their albeit similar, but rather complex design. The most common breakdowns among the rest are accompanied by the following points:
There are even more reasons for the appearance of breakdowns. The most common of them are the following:
Important! The last breakdown is relevant for cheap devices that use low-quality boards.
If you go deeper, then you can identify several other, more rare, but no less interesting reasons, due to which the LED lamp may not work:
In such devices, the contacts may be initially poorly soldered, or a cheap capacitor is used instead of the driver. This is a so-called manufacturing defect.
To carry out high-quality repairs that guarantee the serviceability of the product and its long-term operation in the future, painstaking preparation is required. First, dismantle the chandelier, wall lamp. In the case of table lamps, simply unplug them from the mains supply. In the future, some tools and materials will come in handy, including a screwdriver, pliers, electrical tape, a knife. Pliers or pliers come in handy if the device body is connected using special twists. Use a multimeter to check the contacts.
Since LEDs are small in size, tweezers are useful for manipulating them. Subsequently, if an open circuit is detected or an element needs to be replaced, a soldering iron may be required.In order to replace LED diodes, use a drill with a variety of drills.
Do not forget that each tool must be electrically insulated - it is forbidden to work with pliers or pliers with bare metal handles.
Remote control LED pendant lights are relatively new. Their device is not familiar to everyone, so we will briefly consider the design of the devices.
In the simplest configuration, an LED chandelier consists of a body (metal, plastic, glass), a block with a regulator (driver). The last element is used as a voltage rectifier; terminals and clamps are placed on it, to which power is supplied from the industrial network. The power supply is connected to the lamps with wires.
In complex chandeliers, an antenna, a control unit, a regulator (several units) are used, which is necessary for automatic tuning. Raster lighting fixtures contain several drivers and LED lamps of various kinds. The repair sequence directly depends on the specific type of luminaire.
Study the design of the device using the instructions supplied with it to figure out where the control units are. They can be installed both inside and outside the product.
Repairing a chandelier without a remote control is much easier. In such a device, a diode or diode bridge with electrolytes and resistors is installed. There is also a coil with winding to reduce ripple.
To properly repair your outdoor or indoor luminaire, follow the step-by-step instructions:
Let's take a look at the easiest method to test an LED circuit. Start by securing the lamp using a cut plastic bottle with a smaller diameter. A lamp is inserted into it. To supply power, use the auxiliary power supply (in the case of a 12 or 24 V device).
Instead of ringing each LED diode in the circuit, you can resort to a simpler method. Place a jumper between the pins of each diode in turn using tweezers. If there is no jumper, then take any wire, having previously stripped both ends and tinned the contacts.
It is important that the lamp is connected to the network at this moment. As soon as you close the contacts on the burned out LED, the device will light up. If this does not happen, then it is possible that more than one diode has burned out.
Continue visual inspection of the circuit and look for burnout spots, swollen capacitors, examine each track on the board. Solder if any broken contacts are found. If the circuit consists of 10 or less elements, then in no case replace the burned out LED with a wire or a jumper. This can overload the coils and burn out diodes.
Most often, the reason for the breakdown of a chandelier with a remote control is overheating of the matrix. In such a situation, repairs are carried out as follows:
The controller, antenna or control unit may burn out. In this case, a banal replacement of a failed product is required.
VIDEO
Most LED lighting fixtures come with heat sinks. The presence of this element is a sign of the high quality of the device. In these products, a special seat is allocated, and a radiator is used to remove heat. The thermal paste needs to be replaced periodically. If this is not done, then over time the heatsink will lose its efficiency and the board or block will burn out. Disassemble the device and make sure the thermal grease is applied to both planes of the seat.
If necessary, apply a thin layer of special grease yourself to the entire surface of the seat. Too much thermal paste affects heat transfer as negatively as its absence. To increase the heat output, you can screw an additional aluminum plate to the radiator, making sure that it does not block the main airflow.
Do-it-yourself high-quality repair of LED light sources is possible subject to compliance with safety rules and the presence of a structural diagram of the electrical appliance. The article described in detail the main causes and types of malfunctions, and gave recommendations for their search and elimination.
When a chandelier or lamp breaks down or breaks down, many believe that it will be difficult to make it on their own or think that it is easier to take and buy a new one. But today, LED lamps, chandeliers and even lamps are quite expensive relative to others. As practice shows, in most cases it is possible to quickly and cost-effectively repair lighting devices and LED lamps.
Many will be able to make repairs to LED chandeliers, lamps and lamps with their own hands. At the same time, you will save a lot, but we will tell you how to make repairs later in our article.
Experienced electricians before any repair, always check the presence of a 220 volt voltage probe or multimeter on a non-working lamp or chandelier. Do not forget to turn on the appropriate switch when doing this. If everything is in order, go to the next item. In the absence of voltage, we check the wiring and eliminate its malfunction.
Before proceeding with the repair of lighting devices, for those in which lamps with a base are inserted or screwed into the socket it is necessary to check the performance of the bulbs.
Then check for continuity by ringing the fuses , which very often began to be installed recently in new models. The blown fuse is replaced with a new one. And be sure to perform the next item before turning it on.
In the next step- ring for continuity and absence of short circuit between wires passing through the luminaire body. I recommend reading our article: How to make calls correctly.
Further it is necessary to check the LEDs themselves and the power supply , which steps down the voltage and converts alternating current to direct current. In simple models, a transformerless rectifier consisting of a diode bridge with capacitors can be used to power LEDs. A multimeter is used for testing. The instruction is here. A how to check them read in the next part of the article.
Any LED light bulb consists of one, but more often of several and even dozens of LEDs and their power supply circuits, let's start with the repair of the latter.
So, as I already said, high-power LED (or LED) panels or lamps come with a separate unit, which
But the most common are inexpensive LEDs. lamps made in China with transformerless rectifier consisting of a diode bridge with capacitors and LEDs on one board. More powerful and more expensive models come with a dedicated driver for power supply (see picture on the right).
We will consider the repair of the simplest and most common LED lamps. consisting of a standard base and a group of several dozen LEDs.
We will begin the repair by checking the transformerless rectifier, which should produce a constant voltage in the range of 5 to 20 Volts and a current of up to 0.1 Ampere.
As a rule, most often in such a circuit, a cheap Chinese capacitor for 1 microfarad 400 V burns out (sometimes you can even find it at 250 V). The capacitor in the diagram cannot be checked, so we buy and change it right away. It costs only about 3-5 Russian rubles.
Less often current-limiting low-resistance resistors and diodes break , you can check with a multimeter in ohmmeter mode or continuity in the manner described here.
After making sure the power supply is in good working order - proceed to test the LEDs ... To do this, we take a 9 Volt Krona battery and alternately apply voltage to each LED through a 1 kOhm resistor. On the faulty one - just short-circuit its conclusions , then the rest will be able to earn, but maybe they will shine a little brighter.
If there are no more than a dozen LEDs in the lamp and most of them are burned out, I recommend to those who know how to work with a soldering iron, remove all the old LEDs from the board, then turn them over to the back side, where the contact tracks are located and solder the LEDs from the LED strip directly to them. Look at what happened. The arrows indicate the LED strip from which the LEDs were taken.
Attention , the LED is connected only through a current-limiting resistor or resistance selected individually depending on the voltage of the power supply and the operating current of the LED. I was lucky on the tape and in the lamp the resistors turned out to be the same size. If they are different, then you will have to unsolder and transfer the resistors from the LED strip.
I recommend buying LED strips , on which there are fewer LEDs and their greater power, otherwise it will shine dimly.
In addition, you will learn a lot of useful information on this topic from our article: How to make an LED lamp yourself?
With a variety of lighting devices on the counters of the country, LEDs remain out of competition due to their efficiency and durability. However, a high-quality product is not always purchased, because in a store you cannot disassemble the goods for inspection. And in this case, it is not a fact that everyone will determine from what parts it is assembled. Lamps burn out, and it becomes expensive to buy new ones. The solution is to repair LED lamps with your own hands. This work is within the power of even a novice home craftsman, and the details are inexpensive. Today we will figure out how to check the lighting device, in what cases the product is repaired and how to do it.
It is known that LEDs cannot work directly from a 220 V network. To do this, they need additional equipment, which, most often, fails. We will talk about him today. Consider the circuit of an LED driver, without which the operation of the lighting device is impossible. Along the way, we will conduct an educational program for those who do not understand anything in electronics.
The 220V LED lamp driver circuit consists of:
diode bridge;
resistances;
resistors.
The diode bridge serves to rectify the current (converting it from alternating to direct current). On the graph, this looks like a cut-off of a half-wave of a sine wave. Resistances limit current, and capacitors store energy by increasing the frequency. Consider the principle of operation on the circuit of a 220 V LED lamp.
Having understood the principle of operation and the driver circuit, the decision on how to fix a 220V LED lamp will no longer seem difficult. If we talk about high-quality lighting devices, then you should not expect trouble from them. They work for the entire prescribed period and do not fade, although there are "diseases" to which they are also susceptible.Let's talk about how to deal with them.
To make it easier to understand the reasons, we summarize all the data in one common table.
Good to know! Repair of LED fixtures is impossible to carry out indefinitely. It is much easier to eliminate negative factors affecting durability and not to purchase cheap products. Savings today will cost you tomorrow. As economist Adam Smith said, "I'm not rich enough to buy cheap things."
Before you repair an LED lamp with your own hands, pay attention to some details that require less labor. Checking the cartridge and the voltage in it is the first thing to do.
Important! Repair of LED lamps requires a multimeter - without it, it will not be possible to ring the driver elements. A soldering station is also required.
A soldering station is required for the repair of LED chandeliers and lighting fixtures. After all, overheating of their elements leads to failure. The heating temperature during soldering should be no higher than 2600, while the soldering iron heats up more. But there is a way out. We use a piece of copper core with a cross section of 4 mm, which is wound around the tip of the soldering iron with a tight spiral. The more you lengthen the sting, the lower its temperature. Convenient if the multimeter has a thermometer function. In this case, it can be adjusted more precisely.
But before you repair LED spotlights, chandeliers or lamps, you need to determine the cause of the failure.
One of the problems that a novice home craftsman faces is how to disassemble an LED light bulb. To do this, you need an awl, solvent and a syringe with a needle. The diffuser of the LED lamp is glued to the body with a sealant that must be removed. Passing carefully along the edge of the diffuser with an awl, inject the solvent with a syringe. After 2 ÷ 3 minutes, lightly twisting, the diffuser is removed.
Some lighting fixtures are made without gluing with a sealant. In this case, it is enough to turn the diffuser and remove it from the housing.
Having disassembled the lighting fixture, pay attention to the LED elements. Burned is often identified visually: there are burn marks or black dots on it. Then we change the faulty part and check the functionality. We will describe the replacement in detail in the step-by-step instructions.
If the LED elements are in order, go to the driver. To check the performance of its parts, you need to solder them from the printed circuit board. The value of the resistors (resistances) is indicated on the board, and the parameters of the capacitor are indicated on the case. When dialing with a multimeter in the appropriate modes, there should be no deviations. However, often failed capacitors are determined visually - they swell or burst. The solution is to replace it with a suitable one in terms of technical parameters.
Replacing capacitors and resistances, unlike LEDs, is often performed with a conventional soldering iron. In this case, you should be careful not to overheat the nearest contacts and elements.
If you have a soldering station or a hair dryer, this job is simple. It is more difficult to work with a soldering iron, but it is also possible.
Good to know! If there are no working LED elements at hand, you can install a jumper instead of the burnt one. Such a lamp will not work for a long time, but it will be possible to win some time. However, such repairs are made only if the number of elements is more than six. Otherwise, the day is the maximum work of the repair product.
Modern lamps run on SMD LED elements that can be soldered out of an LED strip. But it is worth choosing those that are suitable for technical characteristics. If there are none, it is better to change everything.
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LED characteristics ... Information about modern models, electrical circuits of working devices will come in handy. In this article, you will find answers to these and other practical questions.
If the driver consists of smaller SMD components, use a copper wire soldering iron on the tip. A visual inspection revealed a burnt element - we solder it and select the one that matches the marking. No visible damage is more difficult. We'll have to solder all the details and ring them separately. Having found the burnt one, we change it to a workable one and mount the elements in place. It is convenient to use tweezers for this.
Useful advice! Do not remove all elements from the PCB at the same time. They are similar in appearance, you can later confuse the location. It is better to solder the elements one at a time and, after checking, mount them in place.
When installing lighting in rooms with high humidity (bathroom or kitchen), stabilizing power supplies are used, which lower the voltage to a safe one (12 or 24 volts). The stabilizer can fail for several reasons. The main ones are excessive load (power consumption of the luminaires) or the wrong choice of the degree of protection of the unit. Such devices are repaired in specialized services. At home, this is unrealistic without the availability of equipment and knowledge in the field of radio electronics. In this case, the power supply unit will have to be replaced.
Very important! All work on replacing the stabilizing LED power supply is carried out with the voltage removed. Do not rely on the switch - it may be incorrectly wired. The voltage is disconnected in the distribution board of the apartment. Remember that touching live parts with your hand is life-threatening.
You need to pay attention to the technical characteristics of the device - the power must exceed the parameters of the lamps that are powered from it. Having disconnected the failed unit, we connect a new one according to the diagram. It can be found in the technical documentation of the device. This is not difficult - all wires are color-coded, and the contacts are letter designation.
Plays the role and degree of protection of the device (IP). For the bathroom, the device must be marked at least IP45.
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If the reason for the flickering of the LED lamp is the failure of the capacitor (it needs to be replaced), then periodic blinking when the light is off is easier to solve. The reason for this "behavior" of the luminaire is the backlight-indicator on the switch key.
The capacitor located in the driver circuit accumulates voltage, and when the limit is reached, it gives out a discharge. The key backlight transmits a small amount of electricity, which does not in any way affect incandescent bulbs or "halogens", but this voltage is enough for the capacitor to start accumulating it. At a certain moment, it gives out a discharge to the LEDs, after which it switches back to accumulation. There are two ways to solve this problem:
We take out the key from the switch and turn off the backlight. The method is simple, but indications that add value to the switch are no longer useful.
We disassemble the chandelier and change the phase wire with zero places on each cartridge. The method is more complicated, but it retains the functionality of the switch. In the dark, you can see it well, and this is a plus.
Not only LED lamps, but also CFLs are susceptible to flashing. The device of their PRU (starting and regulating device) works on a similar principle, which allows the capacitor to store energy.
Consider an example of a simple LED lamp repair:
Can purchased LED bulbs be repaired? This question, taking into account the high cost of lamps, is quite relevant; a lot has already been written about this on Internet forums. Most often, the issues of repairing lamps bought on Aliexpress are discussed.
In the article "Shopping on Aliexpress - personal experience of shopping in a Chinese online store", among other things, it was told about the purchase of LED lamps, which are so popular recently. Actually, the article began with these lamps: the quality of these lamps left much to be desired, mainly attracted by the low price. But in some places where too much illumination is not required, these lamps came in handy.
With further use, it turned out that these lamps are not as durable as advertised. If the lamps of the Navigator trademark have been working trouble-free for the author of the article for almost two years, then the lamps bought at Aliexpress will fail in a month - another, or even earlier. An indicative case is when the lamp, replaced in the evening, simply did not turn on the next day. As a result, two faulty identical lamps.
Someone else would have just thrown away the unusable lamp, but not the radio amateur. Therefore, radio amateurs first try to find out the scale of the disaster, and, if possible, eliminate the defect. So it was this time. It's not that Chinese lamps are too expensive, but if they can be restored, then you won't have to buy another lamp. As they say, the savings are obvious.
The appearance of these lamps is shown in the figure.
This picture is taken from the Aliexpress website. Apparently, the sellers assumed that someone would disassemble and repair such lamps, moreover, repairs, as they say, are not far off. A larger board is shown in the figure below. It is easy to understand from the inscription on the board that the lamp is assembled from 34 LEDs of standard size SMD2835 (2.8 * 3.5 mm).
Disassembling the lamp revealed that there is a small power supply board inside. In the photo, only capacitors are visible, all other parts are made by SMD installation and are located on the back side of the board.
The circuit assembled on the board is shown in the figure below. It’s impossible to come up with an easier one: a conventional transformerless power supply with a quenching capacitor.
The purpose of the parts is clear: resistors R1, R3 discharge capacitors after disconnecting from the network. This is done in order not to pinch the current when you touch these capacitors with your hands. With regard to capacitor C1, everything is clear. If you unscrew the lamp from the socket, the touching of the base may not be very pleasant. It all depends on what charge remains on the capacitor C1.
The charge on the electrolytic capacitor can remain only if at least one LED is cut off. This charge can be "felt" only by disassembling the lamp. Although the resistor R3 has one more purpose.
In the event of a burnout of the LED chain (at least one LED), the voltage across the electrolytic capacitor remains at a level not exceeding the operating voltage of the electrolytic capacitor.
In the diagram, the operating voltage of the electrolyte is 250V. If we assume that the voltage drop across one LED is 3V, then 34 * 3 = 102V will drop on 34 LEDs. It turns out something like a parametric voltage regulator. Therefore, in theory, 250V is more than enough.
Apparently, the Chinese developers reasoned in a similar way: there are lamps in which the operating voltage of an electrolytic capacitor is only 100V. Basically, these are small-sized lamps with a power of 3 ... 5W, where it is difficult to hide a high-voltage capacitor.In the lamp shown in the photo, the operating voltage of the electrolytic capacitor is 400V. But the resistor R3, most likely, will not be superfluous.
Resistor R2 is designed to limit the current through the LEDs. But this is only in the diagram. In fact, there is simply none on the printed circuit board inside the lamp. The function of limiting the current through the LED chain is successfully performed by the capacitor C1. This is a variant of the scheme. Maybe other manufacturers still install this resistor.
So, as it was written a little above, two faulty lamps turned out to be available at once, each only had one LED burned out. Moreover, there were no visible defects in the form of soot on the board, destruction or blackening of the LED itself. Therefore, the faulty LED had to be found. It is quite simple to do this: when dialing with a digital multimeter, the LEDs light up weakly. Naturally, if the probes of the multimeter are connected in the forward direction.
It was decided to use one lamp for spare parts, remove the LED from it and re-solder it to another. Attempts to unsolder the LED using a hot air gun were unsuccessful: the LED did not want to be unsoldered.
The fact is that on the reverse side of the printed circuit board there is an aluminum heatsink, because LEDs, like all semiconductor devices, do not like high temperatures very much. But even without a heatsink, the process of soldering parts from a printed circuit board is much more complicated and dramatic than soldering new parts onto a board.
Repair should be started by finding a faulty LED if the lamp went out completely and immediately. If the lamp starts blinking, or just shines faintly, then the malfunction lies in the power supply. Most often this happens due to a malfunction of the capacitor C1.
The easiest repair option is to replace capacitor C1 with a known good one. A faulty electrolytic capacitor can almost always be identified by eye by a swollen bottom. This is how modern explosion-proof electrolytes behave.
After detecting a faulty LED, it is easiest to unsolder it as follows. The first thing to do is to remove the yellow elastic filter with a thin screwdriver or needle. There will be a metal surface with a crystal under it. Put a piece of solder and a small amount of gelatinous flux on this surface. With a well-heated soldering iron with a power of at least 60 ... 80W, warm up this "sandwich" until the LED is unsoldered from the board.
Somewhat better results can be achieved by using a low-melting alloy such as Wood's alloy instead of solder. Such an alloy in the form of small cakes is sold on radio markets. When mixed with a base solder, usually lead-free, Wood's alloy lowers the melting point of the lead-free solder. Therefore, the desoldering process becomes easier and faster, the likelihood of overheating the printed circuit board is significantly reduced.
Another way to unsolder a faulty LED is with hot tweezers. But not everyone has this tool, and it is hardly worth buying it for a one-time use. Therefore, it is better to make a U-shaped sting, or use the homemade sting shown in the figure below.
After the faulty LED is sealed off, it remains to replace it with a new one. LEDs of standard sizes 2835 or 5730 can be ordered in the same place where the lamps were purchased on Aliexpress. They are quite inexpensive there, about 50 rubles per hundred pieces.
Judging by the price, these are not the best LEDs, but the lamps were still repaired, and the glow of these LEDs is no worse than those that were originally.
Soldering a new LED to the board is not difficult. This can be done with a regular soldering iron. Remains of old lead-free solder should be removed from the board. This is best done with a wire braid with shielded wire.
The braid must be impregnated with flux, in the simplest case, with rosin.Then, with a well-heated soldering iron, pass through the braid along the contact pads, the solder is absorbed into the braid. Then irradiate the contacts of the board with POS 61 solder or the like.
Video (click to play).
Now it remains only to solder the LED installed on the contact pads. It is imperative to cover the LED contacts with a layer of flux, better than a gel-like one. After that, it is enough to touch the ends of the LED with a soldering iron to melt the solder remaining on the contacts of the board. Soldering is so fast that the finger holding the LED on the board does not feel any temperature rise.
