Electronic circuits of LED lamps. Drivers for LED lamps. They are powered by high current, shine brightly, and burn out quite often. If the drivers do not have protection against voltage surges, then cheap lamps quickly burn out without reaching the end of their lifespan.

Hello, dear readers and guests of the Electrician's Notes website.

Today I decided to tell you about the design of an LED lamp EKF series FLL-A power 9 (W).

I compared this lamp in my experiments (,) with an incandescent lamp and a compact fluorescent lamp(CFL), and in many respects it had clear advantages.

Now let's take it apart and see what's inside. I think that you will be no less interested than me.

So, the device of modern LED lamps consists of the following components:

• diffuser
• board with LEDs (cluster)
• radiator (depending on the model and lamp power)
• LED power supply (driver)
• plinth

Now let's look at each component separately as we disassemble the EKF lamp.

The lamp in question uses a standard E27 socket. It is attached to the lamp body using point recesses (cores) around the circumference. To remove the base, you need to drill out the core points or make a cut with a hacksaw.

The red wire is connected to the central contact of the base, and the black wire is soldered to the thread.

The power wires (black and red) are very short, and if you are disassembling an LED lamp for repair, then you need to take this into account and stock up on wires for further extension.

Through the opened hole you can see the driver, which is attached with silicone to the lamp body. But it can only be removed from the diffuser side.

The driver is the power source for the LED board (cluster). It converts 220 (V) alternating voltage into a direct current source. Drivers are characterized by power and output current parameters.

There are several types of power supply circuits for LEDs.

The most simple circuits are performed on a resistor that limits the LED current. In this case, you just need to choose the right resistor value. Such power circuits are most often found in switches with LED backlight. I took this photo from an article in which I talked about.

Slightly more complex circuits are made on a diode bridge (bridge rectification circuit), from the output of which the rectified voltage is supplied to series-connected LEDs. At the output of the diode bridge is also installed electrolytic capacitor to smooth out rectified voltage ripples.

In the above circuits there is no galvanic isolation from the primary network voltage; they have low efficiency and a high ripple factor. Their main advantage is ease of repair, low cost and small dimensions.

Modern LED lamps most often use drivers based on pulse converter. Their main advantages are high efficiency and minimum pulsation. But they are several times more expensive than the previous ones.

By the way, soon I plan to measure the ripple coefficients of LED and fluorescent lamps various manufacturers. In order not to miss the release of new articles, subscribe to the newsletter.

The EKF LED lamp in question has a driver installed on the BP2832A chip.

The driver is attached to the case using silicone paste.

To get to the driver, I had to saw off the diffuser and take out the board with the LEDs.

The red and black wires are the 220 (V) power supply from the lamp base, and the colorless ones are the power supply to the LED board.

Here is a typical driver circuit on the BP2832A chip, taken from the data sheet. There you can familiarize yourself with its parameters and technical characteristics.

The driver operating mode ranges from 85 (V) to 265 (V) mains voltage, it has short circuit protection, and uses electrolytic capacitors designed for long work at high temperatures(up to 105°C).

The housing of the EKF LED lamp is made of aluminum and heat-dissipating plastic, which ensures good heat dissipation, which means it increases the service life of the LEDs and driver (according to the passport, up to 40,000 hours are stated).

The maximum heating temperature of this LED lamp is 65°C. Read about this in the experiments (I provided the links at the very beginning of the article).

More powerful LED lamps, for better heat dissipation, have a heatsink that is attached to the aluminum LED board through a layer of thermal paste.

The diffuser is made of plastic (polycarbonate) and is used to achieve uniform dispersion luminous flux.

But the glow without a diffuser.

Well, we got to the LED board or, in other words, the cluster.

There are 28 SMD LEDs placed on a round aluminum plate (for better heat dissipation) through an insulation layer.

The LEDs are connected in two parallel branches with 14 LEDs in each branch. The LEDs in each branch are connected to each other in series. If at least one LED burns out, the entire branch will not light up, but the second branch will remain in operation.

And here is a video filmed based on this article:

P.S. At the end of the article, I would like to note that the design of the EKF LED lamp is not very successful from a repair point of view; the lamp cannot be disassembled without sawing off the diffuser and drilling out the base.

We are accustomed to the fact that incandescent lamps operate from a network with an alternating voltage of 220 volts. There are, of course, other incandescent lamps that operate on lower voltage, but the glow there is also much less. Here you can observe a relationship - the lower the LED lighting voltage, the less light we get from the lamp. But LED bulbs work very differently. For an LED, voltage does not matter; the intensity of the glow depends only on the current passing through the diode. In this article we will look at what voltage LED lamps can operate at, and we will also touch on the current of LED lamps.

I think that most people who graduated from school a long time ago and did not deal with electricity even then forgot how current fundamentally differs from voltage. And it is advisable to understand this.

Many books use the analogy of a water pipe to explain the difference between current and voltage. But I don't really like this comparison. Any object thrown from a certain height will fall and at a certain moment reach the surface of the earth. He is pulled by gravity. So voltage is the force that makes current move, just as gravity attracts objects. But the current strength, if we continue the analogy, is the size of the object, the larger it is, the harder it will hit. Gravity, like voltage, will not kill if someone does not have an object (current).

Now let's get back to LED lamps. A single LED, or LED chip, is a type of semiconductor that can only carry current in one direction. LEDs can operate on a voltage of 4-12 Volts. And even more, LEDs need constant pressure For normal operation. But in standard electrical network completely different conditions.

In LED lamps, several LEDs are combined in series into one array, and they all receive LED lamp current from a common power supply. Many LED lamps operating from mains voltage have inside special device, a driver that includes a rectifier to convert AC to DC, a transformer to reduce the very high input voltage, and possibly a stabilizing component to reduce current fluctuations.

Most modern LED lamps that are designed for home use and industry are designed for a supply voltage of 110-220 Volts. This is achieved by combining multiple chips as stated above. The driver built into each lamp is responsible for the rest of the voltage reduction and obtaining a constant current.

But if such a light bulb does not have a built-in driver, and you want to start it from regular network, you will need external device, which will perform the same functions, provide the required voltage for the LED lamps and rectify the current of the LED lamp.

Standard wall adapters designed for other equipment will not work; they will not burn out the LEDs, but it is not recommended to use them. They can cause flickering due to improper LED loading and also reduce lamp life. Therefore, you need to use drivers designed only for your type of lamp.

IN Lately LEDs operating on alternating voltage appeared. But since LEDs only pass current in one direction, by their nature they still remain devices that operate on DC. In them, one diode glows at a positive current, the second at negative cycle. Thus, we get a uniform glow. But such lamps also need a driver if they are not designed to operate on 220 volts.

LED lamp current

The brightness of LED lamps depends on the current that will pass through the diode itself. This makes it very easy to control the brightness of such lamps. The same principle of brightness adjustment as for conventional incandescent lamps is suitable here; we change the current strength - the brightness changes. But here one problem arises: each lamp that will operate from an alternating voltage network has a built-in driver that will prevent the brightness from changing. Therefore, if the driver does not support this option, you cannot adjust the brightness.

The electricity consumption of a lamp also depends on the current and voltage passed through. The current strength with which the lamp can operate is usually indicated on the packaging. This can be from 10-100 mA. If it is not specified and you need to know this parameter, it is very easy to calculate it using the formula:

I=(P/U)*1000

Here I is the current, P is the power consumption and voltage. For example, a 220 volt lamp with a power consumption of 12 watts will have a current of 54 mA. The calculated current may be lower than that indicated on the packaging, because some manufacturers indicate on the packaging the power consumption of the LED, not the lamp itself. In addition to the LED, there is also a resistor and other components that also need power.

Implementation projects are increasingly incorporating LED components. LED devices have gained widespread popularity due to significant energy savings and durability, although their cost still exceeds the price tags of more conventional energy-saving and halogen lamps. But LED technology has many other advantages due to its unusual design. A typical 220 device, the photo of which is presented below, is free of massive radiation sources, which allows the body to be optimized in size and performance characteristics. As a result, such qualities as wide functionality, increased ergonomics of control and ease of installation are achieved.

Diode crystal as the basis of a lamp

The basis of any LED device is formed by one or more semiconductor elements that convert electricity into light radiation. These are diode crystals, most often made in the form of a miniature chip. On a small platform of the board there is also equipment for connecting power wires. However, a 220 V device may involve the use of different crystals that differ in design and set of functional components:

• DIP. The most common one is on the surface of which a lens and two conductors are placed.
• SMD. A universally applicable crystal, characterized by its modest size and effective heat dissipation.
• "Piranha". Diode crystal with four outputs for occasions. This configuration makes the emitter more efficient and reliable in operation.
• OWL crystal. IN in this case The diode is integrated into the board, thanks to which the contacts are better protected from overheating and oxidation. At the same time, the intensity of the glow increases.

Basic design of a 220 V LED lamp

In addition to diode crystals, the design includes a base, diffuser, radiator and housing. The board itself with LED elements is the functional core, which is served by the listed components. As for the base, it acts as a supporting link that allows you to integrate the lamp into the socket suitable size. The scatterer makes the photon radiation (converted from the current) more saturated and directed. In more modern versions it is possible to change the physical parameters of the light supply, which is achieved precisely by adjusting the parameters of the diffuser. The radiator unit is also essential in the design of a 220 V LED lamp. One of the main advantages of LED devices is the absence of heating of the housing, which makes the source fireproof. This property is provided precisely by the radiator, which performs the task of heat removal.

Features of low-power lamps

The entry level in the segment is represented by compact devices with 2-4 crystals. The power of each emitter varies from 2 to 5 W. Unlike full-size models, such lamps are characterized by the presence plastic case(in conventional designs glass lids are used), a modest length of about 15 cm on average and a weight of 50-70 grams. At the same time, the design of low-power 220 V LED lamps also requires the presence of radiator units. These can be massive metal modules, the task of which is to protect the plastic case from overheating and melting. In this case, the requirements for heat dissipation are much stricter, so the radiator size is often larger than in powerful LED lamps. As for the quality of radiation, users note the dimness of the light, more gravitating towards bright white and cold spectra.

Lamp shapes and sockets

Especially when choosing non-standard designs, it is important to calculate in advance the possibility of combining a lamp with a lamp in the form of a chandelier, sconce, floor lamp, etc. The most popular form factors include the following:

• LED pear. Standard design that resembles classic incandescent lamps. For such models, E27 type sockets are selected.
• Candle shape. It is on this housing that the device of low-power 220-volt LED lamps, including E14 and E27 sockets, is based. Similar designs are often used in wall lamps and small chandeliers.
• Tubular shape. This is already a non-standard version of the lamp, marked with the designations T3, T4, T20, etc. However, the external resemblance to fluorescent lamps does not in any way transfer to the internal filling, much less to the working qualities.
• Ball-shaped models. For such devices, bases G45, G60 and G80 are used, which can be integrated into different types lamps of both open and closed shape.

Control driver device

This component is not always used, but 220-volt models are the target devices. For them, devices with the HV9910 microcircuit are usually used, which can be powered from a network with a voltage of 8 to 450 V. The microcircuit itself acts as pulse source, equalizing the current. If you plan to use alternating current for power supply, then the 220 V LED lamp driver device will also have to include a rectifier - for example, a bridge type. In common configurations of this type, the HV9910 driver also works in combination with external transistors.

Features of “Armstrong” type structures

The commercial use of lighting devices places high demands on the supporting structures into which the lamps are integrated. This is due both to the need to improve protective qualities and to technical optimization installation process. On this moment Such problems are solved by Armstrong-type platforms, which are a ceiling structure designed for several powerful sources radiation. Unlike standard models, the 220 V LED lamp device for the Armstrong design has the following characteristics:

• Clogging the lamp into a plastic monolithic housing.
• The use of technologically primitive drivers (in order to reduce the cost of design) or their complete absence.
• Using one radiator for several lamps.
• Typical design of the supporting platform, which involves the provision of standard plinths.

Lamp control system

Modern LED devices are equipped with dimmers, through which you can adjust the operating parameters of the lamp. In particular, the user can set brightness parameters. Some versions also include programming elements. Using the built-in timer, you can set the time, glow modes and work sessions with specific glow characteristics. A typical device for a 220 V LED lamp with a dimmer also includes a stabilizer. The fact is that the brightness is adjusted by cutting the voltage and to reliably perform this procedure, a stabilizing component is required. Also, to ensure safety under conditions of maximum power, a safety block is often used, the range of functions of which includes automatic shutdown device or its transfer to a balanced operating mode.

How to make your own LED lamp?

The simplest technique for manufacturing this device is based on a burnt out or unnecessary fluorescent lamp. It is necessary to disassemble its structure, removing the base with the reflector. These parts contain the most important elements from the point of view of the device; everything is disassembled electrical diagram, during which you should remove the fuse from the reflector, as well as the diode crystal. Actually, the new lamp will be based on ready-made lighting equipment, the filling of which can be assembled using an electrolyte. But before this, you should add to the configuration a capacitor unit capable of withstanding at least 450 V, and better yet, 630 V. And if there are not enough LEDs, they can be taken from an LED strip. The main thing is to choose components of appropriate power. The assembly of the structure is carried out using superglue or a compound with suitable characteristics.

Lamp installation

The installation approach will depend on the design of the luminaire. The most difficult in terms of installation are ceiling structures, in the niches of which a lamp is integrated. These are high-power point devices that subsequently operate without lampshades. That is, a barely noticeable part of the optical emitter remains on the surface of the tension or hanging installation. For ease of installation, a 220-volt LED lamp of this type provides fixing rings and clamps. With the help of this fittings, the housing is fastened to the ceiling niche. But before this, a connection must be made to the placement point on the frame side. electric line with a socket into which it will be screwed. Next, the mounting hardware with the lamp is immersed and locked into the hole made in the hanging or tension fabric.

Maintenance minimizes the risks of capital repairs with replacement of diodes. This moment can be postponed in time if regular cleaning device and updates consumables. If insufficient brightness is observed during operation of the device, this is a sign of failure of an individual crystal or an entire group. The nature of the malfunction is precisely determined by the design of the 220 V LED lamp. How to repair devices that have similar problems? First of all, you need to carry out diagnostics and identify specific areas of malfunction. Irretrievably damaged diodes usually have black dots on the surface. They should be dismantled, the place cleaned and new crystals installed. The problem will be that the emission spectrum of diodes may differ even with nominally similar parameters, so difficulties arise in selecting the optimally appropriate emitter.

Conclusion

The use of LED lamps justifies itself both in the industrial sphere and in everyday life. If at the dawn of this technology its advantages in the form of energy savings and long service life came to the fore, today control capabilities are increasingly valued. However, new problems also arise, also caused by the multi-component design of the 220 V LED lamp. Repair in the event of serious breakdowns requires the need full analysis product and subsequent re-soldering of conductors. At least this applies to diode replacement operations. The system also includes drivers, controllers and fuses. This electrical equipment also often fails. But these disadvantages can also be minimized by using not cheap Chinese LED components, but products from companies like Osram or Philips.

For many apartment buildings The problem of lighting staircases is relevant: good lamp It’s a shame to put them there, and the cheap ones quickly fail.

On the other hand, the quality of lighting in this case is not critical, since people are there for a very short time, it is quite possible to put paws with increased pulsations there. And if so, then the circuit of a 220 V LED lamp will turn out to be quite simple:

List of denominations:

• C1 – capacitance value according to the table, 275 V or more
• C2 – 100 µF (voltage should be greater than what drops across the diodes
• R1 – 100 Ohm
• R2 – 1 MOhm (for discharging capacitor C1)
• VD1 .. VD4 – 1N4007

I have already given a diagram for connecting an LED strip to a 220V network, so you can simplify it by throwing out the current stabilizer. A simplified circuit will not work over a wide voltage range, this is the cost of simplification.

Capacitor C1 is the component that limits the current. And the choice of its value is very important, its value depends on the supply voltage, the voltage on the series-connected LEDs and the required current through the LEDs.

For 1 LED in the assembly, filter capacitor C2 should be increased to 1000 µF, and for 10 LEDs, to 470 µF.

From the table you can understand that to obtain maximum power (just over 4 W) you need a 1 μF capacitor and 70 20 mA LEDs connected in series. For more powerful light sources would be better suited 220 V LED lamp circuit using pulse width modulation to convert and stabilize the current through the LEDs.

Circuits based on pulse width are more complex, but have advantages: they do not require a large limiting capacitor, these circuits have high efficiency And wide range work.

I ordered several LED lamps in China. The converters of these lamps are based on driver microcircuits developed in China. Of course, the quality of operation of these circuits does not yet reach Western standards, but the cost is more than affordable.

So, specifically in the latest LED lamps, the WS3413D7P microcircuit was installed, which is LED driver with active power factor correction.

What do we see in the diagram? All the same diode bridge VD1 - VD4, smoothing capacitor C1. The remaining components work and are needed for the operation of the D1 chip. Resistor R1 is needed to power the microcircuit itself at the initial moment of time, and after startup the microcircuit begins to be powered from its output through the chain R5, VD5. Capacitor C2 filters the power supply for its own needs. Capacitor C3 is used to set the conversion frequency. Resistor R2 is needed to measure the current through the LEDs. A divider on resistors R3, R4 allows the microcircuit to receive information about the voltage on LED assembly. Inductor L1 and capacitor C4 are needed to convert pulsed energy into constant energy.

There are a bunch of other varieties of microcircuits, but there are only three main types of high-voltage LED drivers: based on capacitive damping reactance, active damping current stabilizer and pulse stabilizer current

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14 thoughts on “ 220 V LED lamp circuit”

1. Igor

   Even with the “discarded” stabilizer, light It turns out to be too expensive for an entrance. There it is better to screw in a regular Ilyich Edison light bulb with a diode, which is mounted in a slightly modernized socket.

   1. Valery

      Not in the socket, in the switch, there is more space there.

2. Greg

   I don’t know what Igor saw here that was too expensive, but if you save as much as possible, you can throw out the resistance and the bridge. Will remain: C1, as reactance, one diode for rectifying the variable and C2 (increase the capacitance by 2-3 times) for smoothing out ripples. The costs of power supply and replacement of incandescent lamps are much higher than even the original version of the circuit. They are very uneconomical, and from all angles. Therefore, they get rid of them wherever possible. And in the entrances - this is extremely important and extremely necessary, as Ilyich used to say.

3. admin Post author

   The incandescent lamp has a short lifespan, on the box they write 1000 hours, with 24-hour operation this is 42 days. IN best case scenario The light bulb will last for several months.
   Powering the lamp with half-wave voltage should significantly increase the resource (supposedly up to 100 times), but the light output will drop by more than half. And the light bulb will flicker at a frequency of 50Hz.
   To return the frequency to 100Hz, it is enough to turn on two identical light bulbs in series - and the resource will increase and the frequency will not decrease.

4. Alexandre

   In the first circuit, capacitor C1 must be taken to a higher permissible voltage in the network 220 V this effective voltage Maximum 220 * 1.42 = approximately 320 V; besides, as a rule, the capacitor indicates a constant voltage and the network is 50 hertz. I recommend taking at least 450 V. One diode, as Greg writes, will not work like that for LEDs or rectifier diode reverse voltage will act. I recommend throwing out the diode bridge and C2 in parallel with the LEDs in reverse polarity, putting the diol one period will go through the LED, the other through the power diode. The LED can be taken from faulty flashlights.

5. Greg

   Well, the LEDs must withstand reverse voltage, but the idea is good. Why waste one period? C2 - we throw it away, yes, and instead of the power one proposed by Oleksandr, we put another light one - let them blink alternately, increasing the overall luminous flux and protecting each other from reverse voltage. And considering that some flashlights contain 20 super-bright LEDs, you can pick a lot. You can take the whole thing from many hand-held lanterns - the handle is made in the form of an elongated bulb with a circular diffuser.

6. Alexandre

   This diagram It’s possible not only in the entrance, as (Igor) suggests, but anywhere, for example, lighting a personal plot according to Greg’s scheme through a step-down transformer for safety and two groups of LEDs connected in parallel and in opposite polarity. Or lighting a caisson, the soul of summer.

7. Anatoly

   I often saw flickering incandescent light bulbs in hallways, where a “cunning” cartridge with one diode was used. In my opinion, it’s perfect for an entrance, energy saving and unpresentable appearance. Scheme No. 1 is quite suitable for the house, I’ll copy it for myself.

8. Nikolai

   I disassembled a “silent” 11 watt LED lamp (100 equivalent to incandescent). What the author calls a driver regular inverter, the circuit of which has entered everyday life everywhere, from light bulbs to computers and welding machines. So my lamp has 20 diode light-emitting elements. While researching them I came to the conclusion that they are included as Christmas tree garland— consistently. It was not difficult to detect a faulty diode. By soldering a resistor jumper of about 50 ohms, the lamp was restored. So the light emitters do not operate at 9.8 volts, but at the entire voltage supplied by the inverter. That is 220 volts.
   Next - I have an ERA bat flashlight, with a 6-volt battery and a fluorescent lamp. This lamp shines very humidly at its 7 watts. And the battery lasts for 4 hours. What I did was to remove the diode bridge and the board with light emitters from the “driver” circuit. At the soldering points of the wires from the inverter, marked + and -, I soldered this bridge, observing the polarity. The input of the bridge was supplied with alternating voltage, which was generated by the regular generator of the Era. The lamp worked as it should. The light output remained the same as from a 220 volt network. Since the idle speed of the generator provided this voltage to the light emitters.
   Something like that.

LED lamps are the most expensive lighting. But their quality and durability do not always correspond to the parameters indicated on the packaging. It’s a shame to throw away a lamp that has not served its intended life, having invested significant budgetary funds into it.

If you have a multimeter and soldering iron skills, then a faulty LED lamp can be repaired, saving money.

Design of LED lamps

The design of an LED lamp is slightly different from the design of a CFL. The figure shows the components that make up the lamp.

1. Diffuser. Designed to uniformly distribute the light flux in space and eliminate glare when looking at the LEDs.
2. LEDs.
3. LED base with printed conductors for their serial connection.
4. Cooling radiator. Necessary for removing heat generated during LED operation.
5. Driver. Generates the voltage required for LED operation.
6. Driver (lamp) housing.
7. Base.

Only the functional purpose needs explanation drivers. Light-emitting diode - semiconductor device, emitting light when current passes through it. Like a regular diode, it conducts in only one direction. When the polarity changes, the current through it equal to zero. Like regular diode, the voltage at the LED terminals does not exceed a few volts and does not change with increasing voltage.

Therefore, when serial connection LEDs, the voltage required for operation is calculated by multiplying the number of products by forward voltage drop current through them. It can be found in a reference book or measured. When connecting the required number of LEDs to a 220 V AC network, you need:

• reduce the voltage to the required value;
• convert from variable to constant;
• smooth out pulsations;
• protect the driver and its load from short circuits;
• protect the network from interference generated during device operation.

To reduce the voltage use:

• circuits with a capacitor;
• circuits with a step-down transformer;
• inverter circuits.

Circuits with a capacitor used in most LED lamp drivers for household use. They are simple and cheap, but this is their only advantage. Functionally, they are similar to a circuit with a quenching resistor connected in series with the load, through which the excess voltage “drops”. The use of a resistor is impractical, since it produces power comparable to or greater than that of the LEDs themselves.

The capacitor is on alternating current performs the same function - it also extinguishes voltage. Elements on the diagram C2, C3 And R1 designed to reduce the voltage to the required value.

The disadvantage of this scheme is the dependence of the load voltage on the supply voltage. The current through the LEDs is unstable and sometimes exceeds valid values. At this moment, the diodes may fail.

The second disadvantage is no galvanic isolation from the network. When repairing lamps do not touch live parts. Although the voltage on them is not dangerous, the “phase” of the supply network can come directly.

Transformer circuits used in high-power LED lamps, inverter- at large quantities LEDs or, if necessary, dimmable lamps.

A diode bridge is used to rectify AC voltage VD1, and to smooth out pulsations - an electrolytic capacitor C4.

Resistors R2 And R3 necessary to limit the current when voltage is applied to the circuit. A discharged electrolytic capacitor has a low resistance and at the first moment of time the current through it is large. It can damage the semiconductor diodes of the rectifier. Additionally, these resistors act as fuses during short circuits. Resistor R4 discharges the capacitor after disconnecting from the network to ensure the lamp goes out as quickly as possible.

Details R2, R3 And R4 some manufacturers do not install. Capacitor C1 needed to prevent interference from lamp operation from entering the power supply.

Diagnostics and replacement of LEDs

Before starting repairs, remove the diffuser. Removal methods vary depending on the lamp design. Most of the diffusers can be removed with a screwdriver, for which you need to pry it in several places, finding a weak spot.

LEDs need to be inspected: black dots on some elements indicate their failure. The quality of soldering is also inspected - a broken contact in a series chain of LEDs interrupts their power supply. The same thing happens when any of the diodes fail.

The serviceability of the LEDs is checked with a multimeter. Their resistance in the forward direction is measured. It should be small; the value for comparison is determined on serviceable elements. When checking, functional diodes glow dimly. You can test LEDs by applying voltage to them from a 9 V battery through a 1 kOhm resistor.

Discovered faulty elements are desoldered from the board, and a jumper is soldered in place where they are installed. If there is a donor lamp, replace the LEDs, or use parts from LED strip with similar design and characteristics.

Solder the LEDs carefully. To do this, first heat the solder on one side and remove it using suction devices. If they are absent, after the solder has completely melted on one of the terminals, it is removed by vigorously shaking the board. Residues are removed with a clean tip (you can also shake it first) with a generous amount of rosin. The second pin is easier to unsolder.

After installing the jumper instead of the diode, the entire lamp will glow dimmer. This is due to the fact that total resistance chains, although slightly, will decrease. The current through the lamp will increase, resulting in more voltage remaining across the capacitor. If one or three diodes are removed, this will not affect the operation of the lamp. But when there are few of them left, the increase in current will become so noticeable that the remaining parts will overheat, and the failure process will take on an avalanche-like character. Therefore, in case of widespread failure of LEDs, leave the lamp as a donor of parts, replacing it with a new one.

Driver repair

The weak point of drivers is current limiting resistors. They are checked first. You can replace burnt elements with the same or the closest resistance values.

Examination semiconductor diodes rectifier and capacitor performed with a multimeter in resistance testing mode. However there are more quick way check the serviceability of this section of the circuit. To do this, the voltage across the filter capacitor is measured. The expected value is calculated by multiplying the nameplate voltage on one diode by their number. If the measured voltage does not correspond to the required one or is zero, the search continues: the capacitor and diodes are checked. If the voltage is normal, look for an open circuit between the LEDs and the driver.

You can check diodes with a multimeter without removing them from the board. Short circuit in the diode or its break will be visible. If there is a short circuit, the device will show zero in both directions; if there is a break, the resistance in the forward direction will not match the resistance open pn junction. You will recognize it on working elements. A short circuit in the diodes additionally leads to failure of the limiting resistor.

Repairing a transformer driver is a little more complicated than usual. But with the inverter you will have to tinker. There are more parts in it, and most importantly, it always includes a microcircuit. In order to draw a conclusion about its malfunction, you will need to either study in detail the principle of operation of the driver, or make sure that all the parts surrounding it are in good working order.