The LED spotlight does not light up. How to repair an LED spotlight yourself. Eliminating flickering LED spotlights
However, in reality it turns out that after a very short period of time a breakdown occurs. After connecting to the network, the spotlight does not light up, but only blinks or blinks at a certain frequency.
LED floodlight matrix
Finding out the cause of this phenomenon is quite simple. You need to take a closer look at the LED itself when the spotlight is on. 
Bright flashes will of course blind. Therefore, use tinted glass.
Through it you can easily see the very individual elements that flare up. 
High-power LEDs consist of many one-watt crystals. They are connected in series into separate lines using thin gold wires. 
By the number of LEDs you can easily determine the power of the spotlight. 
In most cases, all crystals shine with a bluish tint, and white light is formed due to particles of phosphor, which is part of the compound. 
During operation, the crystals become very hot. The heat generated in this case is transferred to the metal plate. 
But why do only 10 LEDs light up in the photo above? Did 40 out of 50 just burn out?
LED matrix circuit
Since the LEDs are connected in series, it only takes one to break the circuit for them all to stop lighting.
A break occurs when the connecting wire burns out due to a significant excess of the rated current. 
But there is another reason. Due to manufacturing defects or overheating, the crystal structure is destroyed and breakdown occurs. 
The most unpleasant situation is when the contact between the crystal and the connecting wire does not completely burn out, but is broken (temporarily disappears). In this case, the spotlight shines normally for 1-2 days, and then suddenly starts blinking like a strobe light.
After some time, it starts working normally again. In this case, identifying a breakdown can be very problematic.
What will happen to the spotlight if only one LED breaks down? Here is a diagram of a 50-watt matrix connected to a 1.5A current source 
In normal mode, all current is distributed evenly between all lines. Flows through each LED rated current at 300mA.
In the event of a breakdown, only one LED actually shorts out.
Due to the reduced resistance, most of the current flows into the line with the broken element. 
This instantly leads to burnout of the connecting wires. After which, the entire line is turned off.
Now a current higher than the nominal current begins to flow through the remaining LEDs - 375 mA. This will certainly cause overheating and another breakdown. 
This means that another line will turn off. 
And behind her is another one. 
And another one. Until they all burn out. 
But unlike this simulation, in reality, the last line does not burn out.
This is because the power supply has overvoltage protection.
The driver increases the voltage to produce a rated current of 1.5A. But due to abnormal LED resistance, the voltage rises above the permissible level. 
The protection is triggered and the driver is disabled. Soon the voltage drops and it turns on again. This is where rhythmic blinking occurs.
To be fair, it must be said that these matrices belong to the first generation. Today there are already modified models with modernized drivers.
On them, when one line burns out, the current in the others does not change. True, their price is many times more expensive.
Cause of LED breakdown
But what causes the very first LED to burn out? Factory defect or other reasons?
Why don’t manufacturers make one large crystal at all, but use many small ones? After all, the failure of one sooner or later leads to a malfunction of the entire matrix.
Imagine that every hundredth emitter will be defective. We will get a very large percentage of suitable ones from the total number. At first glance, not bad. 
But if 50 emitters are used in one LED, then the probability that there will not be a single defective one among them is only 60%. 
This means that 2 out of 5 finished devices will be defective. Wouldn't it be better to make one big crystal? 
But it's not that simple.
Increasing the size of the crystal by 2 times will lead to an increase in its volume by 8 times!
In this case, the surface area through which cooling occurs will increase only 4 times.
1 of 2
All this will cause thermodynamic stress and lead to inevitable overheating.
Overheating is the main enemy of not only LEDs, but also other semiconductors.
Overheating causes degradation of the crystal. And it is precisely from this that LED spotlights most often fail and begin to flicker.
For it to work out its stated service life, the temperature of the LED crystal should not exceed 85 degrees. It will be less than 50C, consider that you have bought an “eternal” lamp.
Spotlight housing
Overheating occurs due to the extremely poor quality of the housings, which act as heat sinks. They are made not from pure aluminum, but from silumin. Thin metal is simply not capable of dissipating heat effectively. 
You can even conduct a visual experiment. Take and heat the center of the spotlight radiator with a burner.
When heated, significant deformation will occur, which will disappear after cooling. However, even being cold, the surface will already be far from perfectly flat. 
This curvature is usually formed due to repeated thermal deformation after prolonged periods of operation of the spotlight. Due to the curvature and reduced area for cooling, overheating and thermal breakdown of the semiconductor occurs.
And because of this temperature change, it can break the wiring coming from the LED crystal. It is not burnout that occurs, but rather their breakage. 
This can be easily checked by pressing on the matrix at various points. In this case, individual lines or every single LED will light up.
All this happens due to the fact that the heat sink area in the spotlight body has an uneven surface and the matrix does not completely adhere to it. As a result, uneven cooling and deformation during heating are observed.
How to repair
How can one simply repair and correct such a design defect so that the floodlight works for its stated 50,000 hours?
To prevent the LED matrix from overheating, you just need to install a thick aluminum plate under it. 
This plate can be glued to silicone, which will be stable when heated to 200 degrees and will not leak or melt. Or use heat-conducting glue that can withstand heating up to 300C or more.
Do not use thermoplastic adhesive based on ethylene vinyl acetate. It will flow for you even at 60C! 
Such an upgrade will ensure good heat transfer and will reliably prevent deformation.
In this case, it is better to place the plate across the outer ribs on the body. This will use more of them and improve cooling.
LED floodlights are in great demand among consumers for illuminating shop windows, store facades, courtyards in private homes and other objects. They are durable, have good light intensity and consume much less energy compared to conventional incandescent lamps.
But any equipment has a certain service life and is not guaranteed against breakdowns, therefore it requires repair. It is always cheaper to fix problems yourself than to contact specialists in workshops. Let's look at a simple repair of some faults on LED floodlights, but before describing the repair process, you need to study what types of floodlight designs there are and the principle of their operation.
LED spotlight operation
The voltage from the power source is supplied to the electronic board, the converted current is supplied to the LED element, which emits streams of light. The designs of spotlights may be different, but they all have common elements:
- Power supply;
- Electronic current and voltage conversion board;
- Operating mode control drivers;
- Heat sink;
- Optical elements, lenses, mirrors built into the body;
- Terminals for connecting wires and fixtures for fastening the housing.
Floodlights have LEDs of different sizes and power, but the principle of operation and symptoms of malfunction are common.
Basic spotlight malfunctions
Most often, the malfunction of spotlights is manifested by the following symptoms:
- Complete absence of glow when turning on the power;
- LED flickering;
- Dim glow, not at full power;
- Changing the shade of emitted light;
There are obvious signs of deformation of the housing, destruction of the LED structure, after mechanical shocks or breakage, burnt out wiring, which are visible visually.
Main causes of malfunctions
Manufacturers make LED matrices and conversion boards that are reliable and, if used correctly, guarantee a minimum trouble-free period of up to 5 years. Most often, malfunctions occur for the following reasons:
- Unstable characteristics of the electrical network, voltage and current surges exceeding the operating mode values;
- Short circuit of a phase to the spotlight body or neutral wire;
- Incorrect connection;
As a result of these violations, the electronic board on which the floodlight control drivers, voltage and current converters that power the crystal structure of the matrix with LEDs are programmed may fail.
The LED matrix in spotlights can consist of several dozen elements. If the structure of 3-5 crystals in the matrix is destroyed, the spotlight can function, but with a larger number of faulty elements, irreversible processes disrupt the operating mode and all the crystals burn out. In this case, a complete replacement of the matrix is required.
Diagnosing a fault on an LED floodlight
Let's consider identifying a fault on a floodlight, which is in greatest demand among consumers, rectangular in shape with a matrix of 9 diodes, with a power of 10 W. One of the models in this series is the Volpe 10W floodlight with a luminous flux of 750 Lumens.
Regardless of the brand of spotlight, diagnostics begins with a visual inspection:
- The integrity of the wiring from the power source is checked, the absence of breaks, burnt insulation and kinks in the cable, where there may be a break in the current-carrying conductor hidden under the insulating layer;
- The body of the spotlight and the LED matrix are inspected for absence of deformation, cracks and chips;
- If there is no glow at all, first of all you need to unscrew back cover housing and check the voltage at the input and output of the converter electronic board. There should be 220V AC at the input; if there is no voltage, then the reason is not in the spotlight, but in its power supply circuit; measurements can be carried out with a conventional multimeter. The output terminals are 12V DC.
- If there is no voltage at the output, the fault should be looked for on the voltage converter board. Inspect the board for oxidized contacts, tin cracks in solder areas and burnt parts;
- If there are no signs of malfunction in all of the listed points, the last element remains, this is the LED matrix.
Repair and replacement of faulty elements of LED spotlights
Faults such as broken wires can be resolved quickly and do not require special qualifications. Most complex repairs is to identify a faulty element on the printed circuit board of the driver, voltage converter and replace the LED matrix. Therefore, to make repairs yourself, you must have certain knowledge and practical skills in electrical engineering, be able to read diagrams, use measuring instruments and a soldering iron. If you don’t have such experience, it’s better to turn to specialists.
The most in a simple way is the replacement of faulty elements with similar ones; they can be purchased in electrical goods or removed from spotlights on which other parts are faulty. Assemble one working one from two or three faulty ones. A matrix with LED crystals filled with compound material cannot be repaired.
Tip No. 1 If 2-3 diodes out of 9 have burned out in the matrix, then you don’t have to wait for it to burn out completely; this can have a detrimental effect on the drivers and voltage converter. Change the matrix at the first sign of malfunction.
Replacing the spotlight matrix
- Unscrew the front cover of the case, which presses the glass;
- Unscrew the screws and remove the reflector;
- Unsolder and unscrew the faulty matrix;
- We solder the new matrix and assemble the spotlight in the reverse order.
Sometimes the wires from printed circuit board pass to the matrix through the holes of the metal substrate, which plays the role of a radiator for the matrix. At the transition points, they must be insulated, especially the positive wire, so that there is no short circuit to the housing.
Tip No. 2 When replacing the matrix, wipe its substrate and the surface on which it is screwed. Lubricate these places with heat-conducting paste, only then screw the matrix to the body.
When replacing the matrix, be sure to observe the polarities, the red wire is positive, blue or black is negative, yellow-green is on the body.
LED spotlight repair. Shown is a very low-cost option for do-it-yourself repairs
LED floodlight by installing an LED COB chip. The LED COB chip has a built-in 220 Volt power driver. COB technology(Chip On Board) is widely used in the production of LEDs by placing many LED crystals on the chip body board, which allows you to obtain diffused light from a group of powerful light-emitting SMD elements. Modern miniaturization makes it possible to place on the same board and SMD elements of the driver for converting the 220 V mains voltage into a constant supply voltage for the LED assembly. This solution significantly reduces the cost of the final product. In my case, the repair received a symbolic price, and its simplicity allows me not to think twice about finding the causes of the malfunction. For details of the floodlight repair scheme with installation of an LED COB chip, see below with photo and video illustrations.
DIY LED spotlight repair
The original LED spotlight worked for almost four years and after a month of unstable operation it finally went out. Diagnostics by external inspection did not reveal a specific breakdown. No damage was found to the driver parts.
However, the body of the spotlight was made well and the issue of repair was raised. In the process of selecting parts, an offer was found for the sale of an LED COB chip with a built-in power driver from a 220 Volt network. The spotlight was supposed to be installed in a specific location that required only local lighting. An LED COB chip with a power of only 5 Watts was selected. The chip with driver was ordered from the online store using the link http://ali.pub/42hhpy . You can also purchase chips of greater power there.
The spotlight is installed at a given location and controlled by a volumetric motion sensor. The cost of repairs with the installation of a 5 W LED COB chip is simply ridiculous in terms of details. See the result of the projector repair work in the video.
For normal operation The chip, like all LEDs, requires a gentle temperature regime. The temperature of the chip was monitored during long-term operation of the spotlight at room temperature. The chip only heated up to 30º C.
LED COB chip with a built-in driver powered from a 220 Volt network is a good alternative to replacing a driver or LED when repairing LED spotlights.
Let us remind you that the service life of LEDs is the longest among lighting sources. Premature failure of LED floodlights is associated with several factors, some of which are quite predictable.
The first and most common
The purchased spotlight had a minimum price. In this case, its inoperability is directly related to the quality of the components used. In such spotlights, the cheapest and most inappropriate power supplies are installed; it is not uncommon for the power supply to not even have a degree of protection and not be located in a closed housing (meaning the power supply housing).
The contacts in the spotlight's power circuit from the mains to the power supply and from the power supply to the LED have a poor connection, which also leads to a short circuit and failure.
The degree of protection does not correspond to the declared one. In cheap options, instead of a silicone seal, a cheap rubber analogue is installed, which simply collapses due to time and differences in ambient temperature.
The second case, which also occurs
The LED spotlight has a manufacturing defect. Yes, this also happens and no one is immune from it. Most often the reason is in the power supply. If during the first month of operation the lamp fails, then it is most likely that it is the power supply. In practice, if a spotlight has worked for more than 1 month, then it must work out the entire declared service life.
But in any case, you can rest assured that if the spotlight fails due to a manufacturing defect, then most likely it can be replaced under warranty, which is still nice.
The third case also happens
Most often it is found in enterprises. This is a failure due to strong and long voltage drops. Although the LED spotlight is designed to withstand voltage surges, but only for short-term ones. In the case of factories and enterprises, sometimes the voltage drops catastrophically at times and at the same moment rises. At such moments, the power supply simply cannot cope and because of this the LED simply burns out.
Here the warranty will not help, since this is not a manufacturing defect, but a violation of the operation of the lamp.
Should I repair the LED floodlight?
Today, it is worth admitting that this idea makes absolutely no sense. The cost of components in retail sales often reaches the price of a more or less high-quality LED spotlight. And the most unpleasant thing is that no one will give you a guarantee that if you buy, for example, a power supply instead of a non-working one, it will match the LED with which the faulty power supply worked.
Therefore, if the LED spotlight does not work and there is no warranty for it for any reason, you should safely go and buy a new, high-quality LED spotlight. We wrote about how to choose the right LED spotlight.
The Navigator NFL-P-30-4K-BL-SNR-LED LED floodlight came in for repair with the following diagnosis. Only part of the LED spotlight works, and the part that glowed resembled the operation of a strobe light more than a spotlight. There was no circuit diagram for this device; once again I had to make sure that the smaller the circuit, the more amazing the imagination of the engineer who created it. But if we do not consider the inverter, then the rest of the design caused serious bewilderment; the quality is much higher compared to the inverter. Although the LEDs themselves (presumably 5730-1) are soldered at random, in addition to soldering to the contact, the LED body is also soldered, with its cooling pad, to a thin substrate 2-2.5 mm thick, made of aluminum (maybe ceramic).
Rice. 1 Dismantled LED, 1 - contact pads, 2 - radiator pad (the contact under the radiator pad came off along with the LED)
The substrate itself is mechanically pressed against a powerful blackened radiator, the very appearance of which evokes respect. Lead wires in a silicone sheath, which is rarely used in household appliances, also evoke positive emotions.
Rice. 2 Cooling radiator, LED substrate.
And a little fly in the ointment - a powerful radiator does not allow you to painlessly remove faulty LEDs; in the absence of a soldering station, a hair dryer and two soldering irons do not help much; along with the LED, the radiator platform under the LED housing also rose. Inconvenient dismantling coupled with the lack of a block design makes the 50254 V-0.5 LED block unrepairable in domestic conditions (we remind you that overheating the LED crystal above 110C-130C leads to death for the latter), and not every workshop will undertake the dismantling and installation of LEDs, taking into account the cost of the parts plus the work - it's cheaper to buy a new one.
Although the GT-50254 V.06 inverter was a pleasure, a kind of puzzle, it ultimately could not be repaired. During lunch it was unrealistic, and there was no desire to waste time assembling a new inverter. The PWM controller is factory marked AFB3HF, but we couldn’t find one. Almost no analogue came to mind. If we assume that the LEDs are 5730-1, then the output voltage of the inverter is 19V, so with 40 W of power consumption we get 2A at the output, which means the voltage feedback for a current of 0.3V, it was not possible to remember such PWM controllers from memory, and given the fact that voltage feedback is generally on alternating voltage (!!!), all attempts to find an analogue were abandoned. ULVO somewhere in standard range, at the very least, from an external 13.5V power supply, the PWM controller starts up and works stably.
Rice. 3 Scheme LED lamp Navigator NFL-P-30-4K-BL-SNR-LED
Fig.4 Inverter view No. 1
Rice. 5 Inverter view No. 2
UPD 09/12/2014.
From our reader Yuri.
LED floodlight Navigator NFL-50-4K-WH-IP56-LED.
Two faults
- The spotlight will not turn on. The dual Schottky diode in the secondary rectifier in the TO-220 package has failed (these are found in computer power supplies). After replacing the diode, the spotlight turned on.
- The spotlight flickers. Malfunction of the 100 ohm resistor (R5 100 ohms by analogy with the circuit in Fig. 3) in the power supply circuit of the transformer winding (feedback winding), 12V power supply, it also powers the PWM microcircuit.
From our reader Yuriynik.
- When one LED in the line fails. Jumper the faulty LEDs in each six, one in a group. In serviceable sixes, also jumper one at a time (to match the load).
- Electronic ballast relaxes(flickers. zival). Shunt resistor R7 (Fig. 6) with a capacity of 1000 pF
- The LED matrix mode can be changed. To do this, we connect a resistor from 5 to 100 Ohms in series to the positive terminal of the electronic ballast
Rice. 6. Repair of an LED lamp according to the advice of a Yuriynik reader
