Types of breakdowns, and self-repair of LED lamps

Ремонт светодиодных лампПодключение

LED lamps are superior to competitors in almost all positions. But, despite the stated service life, some devices burn out even before the end of the warranty period. Do not rush to throw them away, 90% of burned-out Led-lamps can be repaired.

The device and principle of operation of the LED lamp

To fix a led lamp, you need to thoroughly know its device. Regardless of the type of LEDs used, all lighting devices, including filament ones, have the same structure.

LED lamp on the table

The LED lamp consists of the following parts:

  • LEDs. Most often, LED lamps have SMD and COB chips. Diodes are replaced only with similar ones. If there is no suitable element, solder all the LEDs – they should be the same.
  • Driver . The printed circuit board is inside the case. This block is a current generator. The driver has a high efficiency and a wide operating temperature range (-40….+70°C).
  • Plinth. In LED lamps, it is made of metal or ceramics. It can also be made of heat-resistant plastic. In branded lamps, the base is not soldered – this prevents its oxidation. There are several types of socles, in household lamps, most often, pin and threaded ones are used.
  • Circuit board. It has LEDs on it. The board material is anodized aluminum alloy. Sometimes, for convenience, the places for the diodes are numbered – so as not to confuse the sequence.
  • Radiator. It prevents overheating and premature burnout of the lamp. In budget lamps, the element is made of plastic. In high-quality ones, there are often metal stainless radiators, the thickness of which depends on the power of the diodes.
  • Optical elements. Most LED lamps are equipped with a diffuser. Mostly matte plastic. The diffuser, concentrating the light flux at a certain angle, makes it as uniform as possible.
    Plus diffusers – complete safety. Unlike glass flasks, it cannot burst, creating a risk of injury to people.

The device and principle of operation of the led-lamp:

  • The supply voltage from the cartridge is supplied to the terminals of the base, to which a pair of wires are soldered – through them the voltage is supplied to the input of the driver, and from it the DC voltage goes to the board with LEDs.
  • To scatter light or protect conductive parts from human touch, the board with LEDs is covered with special glass.

Filament is a type of LED lamps . Outwardly, they are very similar to ordinary incandescent lamps. But under the glass bulb is not a tungsten filament, but LEDs that look like filaments.

Driver circuits and their principle of operation

To repair an LED lamp, it is important to understand how each element works. All 220V drivers can be combined into three groups – with current / voltage stabilization and without stabilization.

In fact, only a current-stabilized circuit is a driver. The second option is with voltage stabilization, it is rather a power supply for a led strip. A circuit without stabilization is good because it is the easiest to repair. 

Current stabilization

In this circuit, there is an integrated current regulator SM2082D. Although it has a simple device, it is quite reliable and of high quality, and most importantly, it can be repaired if necessary. Below is a diagram of LED-A60 with a full-fledged driver:

Scheme LED-A60 with a full-fledged driver

How the circuit works:

  1. The voltage from the network through F (fuse) enters the diode bridge VD1-VD4. Here it is rectified and fed to C1 (smoothing capacitor). A rectified (constant) voltage is supplied to the LEDs and to pin No. 2 of DA1 (microcircuit).
  2. From output No. 1 of DA1, a DC voltage is supplied to the LEDs. The value of the latter is determined by the value of R2 (resistor).
  3. R1 has quite a lot of resistance. It shunts the capacitor and practically does not participate in the operation of the circuit. Its task is to quickly discharge the capacitor when the lamp is unscrewed.
    If this were not provided, then when touching the base, a person would receive a strong electric shock, since the capacitor C1 is charged during the operation of the circuit up to 300 V.

With voltage stabilization

This circuit performs stabilization not by current, but by voltage. The figure below is a power supply for a led lamp:

Power supply for led-lamp.

How does it work:

  1. The mains voltage is supplied to C1 (capacitor), which lowers it to approximately 20 V, and then it goes to VD1-VD4. Here the voltage is rectified, smoothed on C2 (capacitor) and fed to the integrated voltage regulator.
  2. Further, the voltage is re-smoothed – to C3 (capacitor), passes through the current-limiting resistor R2 and is fed to the LEDs. 

The option differs from the previous one by the presence of a current-limiting resistor. The essence of the circuit is an LED strip with a power supply.

Without stabilization

Such a driver is used in cheap Chinese lamps. But, with normal voltage in the network – without sudden drops, this circuit is quite efficient. Stabilization of current or voltage is not provided here. There is only a rectification of the voltage and lowering it to the required value.

How the circuit works:

  1. There is a quenching capacitor, which is shunted with a resistor to increase safety.
  2. The voltage is applied to the diode bridge, then smoothed out on a small capacitor (about 10 microfarads) and, passing through the current-limiting resistor, is fed to the LED circuit.

The circuit, in fact, is not a driver. Stabilization is not performed here, so the voltage supplied to the LEDs depends on the mains. If the mains voltage is unstable, the light will flicker.

Such “drivers” are usually found in budget lamps. If the mains voltage is normal, without jumps, then the lamp does not blink and can work for quite a long time.

Voltage rectification circuit, without stabilization

Frequent breakdowns

High-quality led-lamps rarely break, you can’t say the same about cheaper analogues. Breakdowns happen to them, most often the LEDs break through or the driver fails.

LED breakdown

In LED lamps, LEDs are connected in series. The output of one diode is connected to the input of another – the circuit is extremely simple. But it is enough for one crystal to break for the lamp to stop burning.

LEDs are not insured against burnout, so if the lamp does not burn, the first thing to do is to check them. It is very easy to do this. All you need is a multimeter.

How to test LEDs for breakdown:

  1. Examine the crystals. Serviceable ones have a uniform light color, dark spots are visible on broken LEDs.
  2. Solder damaged LEDs. Please note that the maximum temperature that the crystals endure without compromising their properties is +80°C. Use a low-power soldering iron or iron for desoldering.
  3. In place of the soldered LEDs, solder serviceable analogues by applying flux to the pad.

How to check the health of the lamp with a multimeter:

A lamp repaired in this way will work, however, it will shine a little worse. This option works if there are 10 or more crystals on the board. It happens that burnt crystals can be replaced with wire jumpers.

In 220v lamps, LEDs of various types are used – in a plastic case, unpackaged, on transparent ceramics, on a glass, sapphire, or metal strip.

Driver corruption

If in appearance all the LEDs are intact or faulty have already been changed, and the lamp is still off, then it’s time to move on to examining the driver. Most damage can be identified visually – by changing the appearance of resistors or capacitors.

In the absence of visible damage in the driver, research is carried out using a tester:

  1. Check all the elements first, and then the soldering points, as the contacts deteriorate or even disappear due to temperature changes. In the first case, the light is on and off, in the latter it does not work completely.
  2. To determine the damage in the solder, carefully examine it in the light. Carefully heat the places with cracks with a soldering iron.
  3. Diode bridges rarely break down, so they are checked last. If you find a broken diode, unsolder it and check again. If the failure is confirmed, replace the faulty diode with a similar one, observing the polarity.

Video instruction:

Determination of the cause of the malfunction

There are several reasons for the failure of the led-lamp, therefore, before proceeding with the repair, it is necessary to determine why it flickers or does not burn at all.

The first thing to do if the LED lamp does not light up is to unscrew it from the cartridge and screw another one (optionally led) in its place. And, if it lights up, then the cause of the malfunction is in the lamp itself.

Finding faulty LEDs

You can check the serviceability / malfunction of the LEDs using a multimeter. Switch it to the continuity mode and check all the LEDs in sequence. To do this, apply probes to the contacts of each crystal.

To search for broken LEDs, you can also use a 3-4 V battery with soldered contacts. Observing the polarity, apply the wires to the diodes. Healthy crystals will burn, but broken ones will not.

The LED lamp began to flash like a strobe

If the lamp does not go out completely, but flickers, it can also be repaired.

Reasons for flickering LED lamps:

  • Weak or missing capacitor. The problem can be solved by putting a more powerful element. If the voltage of the capacitor is 100 V, and the voltage of the diodes is 180 V, the first value should be increased by 1.5-2 times.
    The second solution to the problem is to connect a second capacitor in parallel (in order to increase the total capacitance and power).
  • Driver overheating. The reason is poor ventilation. The lamp, due to overheating, begins to flicker and blink, and when the current-limiting resistor fails, it will completely go out.

If the LEDs are intact

If all the LEDs are working, and the lamp is off, most likely, the damage is due to damage to the driver elements – resistors, microcircuits, diode bridge, etc.

In this case, it is easier for an ordinary user to buy a new lamp, since repairing an old one will require certain knowledge, skills and abilities. But, before throwing away the lamp, open the board with LEDs and look inside.

To disassemble the lamp, remove the silicone, unscrew the screws and unsolder the “+/-” wires. The assembly can be on spring-loaded contacts or on a soldered jumper. It is she who often burns out due to poor contact.

What will be needed for the repair?

To repair a led lamp, you will need to measure with a multimeter.

Also for repair you will need:

  • soldering iron of low power, with a thin tip;
  • tweezers;
  • wire cutters;
  • platypuses;
  • spare parts – they will have to be purchased depending on the type of breakdown.

It is desirable to have a non-working lamp – it can become a source of necessary details.

Platypuses are called small pliers. They have long grips, which are convenient to hold small parts. In principle, if there are no platypuses, you can get by with tweezers.

How to disassemble the LED lamp?

Repair or alteration of LED lamps is impossible without their disassembly. This procedure can not be called complicated, but it requires a certain accuracy. It is important not to damage any element of the lamp. The printed circuit board requires special delicacy.

Parsing the circuit board of the LED lamp

It is recommended to shoot the disassembly of the lamp on video so as not to confuse the reverse order of operations.

unscrewing

The LED lamp is a fragile device, so disassemble it very carefully, without using force and sharp tools where you can do without them.

Procedure:

  1. Remove the diffuser dome. To do this, take the light bulb by the edges with both hands and with careful rotational movements separate the upper part from the body. The bonding sealant is quite thin, so it usually does not take much effort.
  2. Separate the plate with LEDs from the body by unscrewing the fixing bolts. Use special precision type screwdrivers.
  3. Disconnect the mounting plate from the heatsink. Use an object with a sharp, flat edge, such as tweezers. Gently pry up the edge of the board and remove it entirely.
  4. Unsolder the contact areas of the power wires and finally separate the board with diodes from the rest of the parts.
  5. Separate the base and radiator by rotating. Lay out all the parts of the lamp on the table and start repairing.

Heating with a hair dryer

This option is suitable for lamps with thick glass. A building hair dryer allows you to heat the lamp body to the desired temperature – this is the only way to remove the glass glued to the cylindrical base.

The hot air causes the heated components to expand and the adhesive that holds the glass to become elastic. After heating, the lamp can be easily disassembled into its component parts.

Video on how to disassemble the e27 LED lamp:

Do-it-yourself LED lamp repair examples

Before proceeding with the repair of LED lamps, it is useful to consider this process with specific examples. There are not only many versions of led lamps, but also their breakdowns.

LED lamps can become eternal if you make the LEDs work not at 100 or 120% of their capabilities, but at 50-70% – this will reduce the temperature and prevent overheating, due to which most LED lamps fail.

Do-it-yourself 220 V led lamp repair

The driver, which in 80% of cases causes a breakdown, is not necessarily built into the lamp. It can consist of LEDs alone, and the stabilizing device is built into the luminaire.

If the driver is made separately, repairs are easier to carry out. It is enough to change the lamp and make sure that the problem is in it. If not, then the stabilizer is broken. In lamps with a built-in driver, the situation is more complicated.

The procedure for repairing an ice lamp with a driver:

  1. Turn the heatsink counterclockwise to disassemble the bulb.
  2. Remove the driver. Ring all the LEDs, the diode bridge and the microcircuit with a tester.
  3. You cannot work with SMD components with a soldering iron, so use a hairdryer and a soldering station. Not everyone has these devices, so you need to know how to do without them.
  4. After soldering the microcircuit and the diode bridge, coat the contacts with a special paste and warm it up. This will allow you to later install small elements in place and carefully solder them.
  5. Start with a microchip. Similar parts are sold in a well-known Chinese online store for 50-80 rubles. a piece. Glue the chip to the paste, hold them and solder.
  6. Next is the turn of the diode bridge. You can also buy this part on Chinese sites.
  7. Solder the finished driver to the base. He has a very short wiring, so build them up. This will avoid dismantling the plinth, rolled on the plastic case.
  8. Solder the other side of the driver to the printed circuit board with LEDs. The main thing is not to reverse the polarity. Usually, the poles are indicated on the board and the driver – focus on them.
  9. Check lamp operation. But, if you have no experience in electrical work, do not do this while the lamp is disassembled – there is a risk of a short circuit and electric shock.

LED lamp repair video:

Repair using the example of an ASD LED-A60 lamp, 11 W on an SM2082 chip

Today, powerful led lamps are in use, in which drivers are assembled on SM2082 microcircuits. The following is an example of repairing a lamp that periodically went out and lit up again. Preliminary diagnosis – poor contact.

Procedure:

  1. Use a knife to pry up and remove the scattering glass.
  2. Examine the SM2082 chip. If you have not identified defects in soldering and broken tracks, remove the board. To do this, cut off the silicone and pry the board with a screwdriver blade.
  3. To get to the driver, unsolder it by heating the contacts with a soldering iron – both at once, and move it to the right.
  4. On one side of the driver board there is a 400 V capacitor. On the other side, there is a diode bridge and two resistors. To understand which board has no contact, connect them with polarity – two wires.
  5. Tap the boards with a screwdriver handle. Find out where the fault is – in the contacts of the wires, in the capacitors, in the contact of the central output of the base.
  6. If a damaged contact is found, lubricate it with flux and solder it again.

How to solder damaged LEDs and solder new ones?

To work with LEDs, you need to be able to solder and have all the necessary tools for this. SMD diodes do not have current-carrying elements. Instead, there are special contact pads on the board. For soldering use a soldering iron with a power of 12 watts.

To solder the LEDs you will need:

  • tweezers;
  • blade;
  • flux;
  • soldering iron;
  • holder.

How to solder an LED from an LED lamp with a soldering iron:

  1. Remove the aluminum board by separating the lamp housing from the lampshade.
  2. Check all diodes with a tester.
  3. Bring the burner to the back of the board for 3-5 seconds. Disconnect the diode when the soldering loosens.
  4. Before the base cools down, place a drop of flux on the contact pad and install the diode on top, taking into account the polarity.
  5. Heat the base again and press lightly on the crystal. Hold the diode until the “legs” are securely fixed in the solder.

Video instruction:

Safety precautions when repairing 220 V LED bulbs

When repairing led-lamps, it is necessary to observe elementary electrical safety measures. This will prevent electric shock and injury.

Safety regulations:

  • All measurements and soldering should be carried out only on de-energized boards.
  • Do not leave the soldering iron unattended.
  • Wear protective goggles (there is a risk of the capacitor exploding).
  • Remove the cap with mounting gloves (there is a risk of cuts by splinters).
  • Carry out work in a ventilated area, as inhalation of rosin vapors is harmful to health.

Here are some common questions about LED bulbs. They are the following:

  • Why is it permissible to short the terminals of burned-out LEDs in LED lamps? The led-lamp driver, unlike the constant voltage power supply, produces a stabilized current value at the output, not voltage.
    Therefore, regardless of the load resistance (in a given range), the current will always be constant, which means that the voltage drop across each diode will be the same.
  • What is the service life of a repaired lamp, and how to increase it? There is no exact answer to this question. People who have repaired ice lamps on their own say that they have been working for a year and a half. There is no guarantee that another LED will not burn out due to overheating.
    Definitely, the manufacturer does not want to make “eternal” light bulbs, as this will negatively affect the work of their enterprises.

Most of the breakdowns of LED lamps can be fixed by hand. To do this, you need to thoroughly understand the device of the lamp and the principle of its operation. By learning how to repair led-devices, you can save a lot of money on their purchase.

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