In detail: do-it-yourself repair of a 50 w LED floodlight from a real master for the site my.housecope.com.
Although LED technology (including floodlights) is highly reliable, it also sometimes fails. Repair of LED floodlights allows you to eliminate most of the faults when you need to restore the device to work. Repair work is relevant not only when the device does not shine brightly enough, but also if it completely stops working.
LED floodlight (LED) contains the following components:
LEDs (provide a glow);
drivers (control the operation of the device);
frame;
light diffuser (allows you to increase the efficiency of the luminaire);
lenses (control the shape, color and some other characteristics of the light flux).
The floodlight functions thanks to the coordinated actions of several of its components, including optics, power supply, drivers and heat sinks. In the inner part of the case, there are light diodes, as well as small-sized electronic components. The power supply supplies voltage to the LEDs, where the current is transformed into a luminous flux. Thanks to these actions, the glow of the device is ensured.
The figure below shows a typical wiring diagram for an electron gun driver.
As for the principle of the driver's operation, it does not differ on different floodlights. Power from the mains is supplied to the driver input, bypassing the fuse F1. Further, there is filtration using LC-elements and rectification due to a diode bridge. Smoothing is carried out by an electrolytic capacitor (C13). A constant voltage (280 V) is generated across the capacitor terminals.
Video (click to play).
From the electrolytic capacitor, the voltage is directed through current-limiting resistors to the zener diode (D12) and pin No. 6 of the described microcircuit. The zener diode is responsible for the 9-volt power supply of the microcircuit, which is the main factor that ensures the functioning of the driver. From the capacitor C13, the current flows through the transformer winding (T1.1) through the terminal part of the field-effect transistor (Q1).
Note! The amount of current flowing through the light diodes depends on the parameters of the resistance of the resistors on the microcircuit.
The most common signs of a malfunctioning spotlight are:
the lamp does not light up although the power is on;
light diode flickers;
the glow is too dim, since the lamp burns weakly - not at full power;
the shade of the light flux has become unnatural.
Other signs may also be present, including physical damage to the structure of the case, deformation of the diode, and burned out electrical wiring.
Possible reasons for the incorrect operation of the spotlight:
unstable electrical network (voltage drops beyond the operating current);
short circuit of a phase to the device case or to neutral;
incorrect connection;
overvoltage;
use of overcurrents.
With these violations, the failure of the board on which the drivers, voltage and current converters are installed, supplying power to the matrix crystals, is possible. In a searchlight matrix, damage from 3 to 5 crystals is allowed. If the number of faulty crystals is greater, the floodlight will not be able to work with a sufficient degree of functionality and the matrix will need to be replaced.
First of all, it is necessary to establish the cause of the malfunction of the LED floodlight. As an example, let's talk about testing the performance of a rectangular Volpe floodlight with a matrix including 9 diodes.The total power of the luminaire is 10 W. The luminous flux is 750 lm.
The check is carried out in the following order:
Examine the wiring for physical integrity. Check the absence of breaks, burnt insulation, cable bends. The goal is to ensure that there are no breaks in the conductor.
The body of the device, as well as the LED matrix, are checked for mechanical damage (deformation, chips, cracks).
The next task is to check the input voltage by opening the back panel of the case. The input voltage must be 220V AC. If there is no voltage, the cause of the breakdown is not in the luminaire, but in the electrical circuit. Measurements are carried out with a standard multimeter. The output voltage is 12 VDC.
If there is no output voltage, the fault is looked for on the converter board. They inspect the contacts for oxidation, look for cracks in the tin coating in the areas of soldering or burnt-out elements.
If the above verification methods do not give a result, the matrix is tested for performance.
Eliminating wire breaks does not require special skills from a home craftsman. It is much more difficult to find and fix a breakdown on a printed circuit board, driver, voltage converter or matrix. You cannot do without special knowledge. You will also need the ability to work with diagnostic devices and a soldering iron.
The following parts may be subject to repair or replacement:
limiting capacitor;
power unit;
driver;
matrix.
This component is the cause of a malfunction when the spotlight lamp does not burn evenly, constantly flickering. This problem is usually associated with the fact that manufacturers, trying to save money, install a current limiter that does not match the driver's characteristics.
A common reason for the malfunctioning of a floodlight is a breakdown of the power supply. In such a situation, you can purchase a new power supply unit or pick up this part from another device (for example, from a printer). If you decide to buy a new unit, it is recommended to take it with you to the store, since its technical characteristics are indicated on the case. To get the block, you first need to disassemble the spotlight.
Low-power models often lack a power supply. In such cases, an LED-type driver is used instead of the unit. Since the diode is not able to receive power directly from the network (an alternating current is needed, different from the network one), then the driver is involved. The device operates based on operating temperature and time by varying the output current to the LED.
To replace the driver, disassemble the floodlight to set the technical parameters of the driver, and then contact the store. Just as with the power supply, you can select the appropriate driver from another device.
The most common cause of floodlight malfunctioning is overheating of the sensor, which leads to blown fuses. The searchlight is disassembled, after which the damaged matrix is taken out. To do this, unscrew four screws and unsolder the conductive parts. Next, a layer of thermal paste is applied to the LED and the conductive parts are soldered back. The operation is completed by screwing the matrix into place.
In some cases, the wiring in the die goes through the holes in the substrate. It acts as a matrix heatsink. In the transition areas, the wires must be covered with an insulating layer (first of all, we are talking about the plus wire). This will avoid a short circuit to the device case.
Advice! Before replacing the matrix, clean the substrate and the area where it will be installed. It is recommended to treat these places with a heat-conducting compound.
The shape of the matrix cannot be violated. It is recommended to use only "native" screws in order not to damage the structure. Also, do not forget about the polarity: red wires - plus, black or blue - minus, green-yellow wire is directed to the case.
If at least 2-3 burned-out diodes are found, you should not wait for the matrix to completely burn out. In any case, the device is no longer able to function normally, as a result of which the drivers and the voltage converter will soon fail.
Note! If the matrix does not work with the filled compound element, it cannot be restored.
If, when checking the board, obvious signs of burnt-out elements are found, the device will need to be repaired. The figure below shows the converter circuit for the spotlight.
Before replacing inoperative parts, the LEDs should ring. First, one of the legs of the board is unsoldered, since ringing the soldered elements will not give the correct result. If necessary, burned-out parts are replaced with new ones.
As an example, consider the repair of the SDO01-10 floodlight. The power of the device is 10 W. Visual inspection shows peeling of the protective coating on one of the floodlights. There are also dark spots on the light emitting surface of the matrix.
Repair of a matrix with a damaged LED emitter is possible, but such a part is not cheap. The cost reaches 40-50% of the price of the whole floodlight. In addition, the acquisition of a new matrix presents another difficulty - LEDs often lack markings. As a result, it is not easy to find out the type of emitter.
To simplify the task, we install the driver of the floodlight from the burned-out matrix to the luminaire with a working matrix. On the old driver, the protective resistor has burned out (its nominal value is 1 Ohm), which indicates a breakdown of the diode in the diode bridge at the transition from the key resistor to the control resistor. However, replacing the driver did not restore the functionality of the spotlight.
After further verification, a break in the optical feedback pair was detected. Replacing the pair gave a result - the lamp worked.
The subject of consideration is a model of a powerful searchlight SDO01-30. Devices of this type are used to illuminate large rooms (for example, for industrial purposes).
First, we remove the rear panel from the spotlight and carry out a visual check of the state of the radio components on the printed circuit board. We pay attention to elements that have a suspicious appearance (carbon deposits, deformations, etc.).
Next, we inspect the printed circuit board (by pulling it out of the spotlight) from the semiconductor side. Inspection showed the presence of a pair of blown resistors: R8 (2 ohms) and R22 (1 ohm). Low resistance resistors most often burn out due to the high current passing through them in the event of breakdown of semiconductors or capacitors.
Next to the resistors is the field-effect transistor SFV4N65F. The ringing has identified its malfunction. Since the searchlight circuit was not available, we find out the values of the resistors that burned out by disassembling a working lamp of the same model.
We solder the failed resistors, as well as the transistor. We replace them with new parts.
Some helpful tips for repairing LED floodlights:
When replacing a matrix, be sure to pay attention to the polarity.
It is imperative to remove cured heat transfer paste underneath the die.
Degrease the surface with alcohol.
When soldering, there is no need to overheat the surface. Soldering time - up to 2 seconds. If the matrix is overheated, the crystals will be destroyed or their new characteristics will not allow the projector to function normally.
To repair a high-power floodlight, the knowledge used in the repair of low-power fixtures is enough. There are no special differences between devices of different capacities.
If the matrix with a large number of diodes is not filled with a compound solution, it will be necessary to replace the inoperative diode. A microsoldering iron is required to complete the operation. You need to work carefully so as not to overheat the crystals.
If it is impossible to see the denominations on the burned-out resistances, you cannot do without instructions for the searchlight.It must contain the relevant data.
Anyone can fix a spotlight. However, repair work requires at least basic knowledge of electrical engineering, as well as skills in handling a soldering iron and multimeter. You also need to be able to read diagrams in order to understand the design of a spotlight.
Despite the fact that LED technology is very reliable, it cannot be perfect and sometimes fails. Especially if you decided to save a lot and bought one of the cheapest floodlights. So what to do if your LED spotlight flickers and blinks, or even worse - stopped working altogether, and your warranty for the purchased product ended, or did not start at all. It is possible that you purchased a non-certified product in a reliable store with a good reputation, and at your own risk and risk ordered the most budgetary LED floodlight directly from China, through Aliexpress, for example? And here in front of you lies and blinks or does not shine at all, a far from cheap lighting device, and you do not know what to do? Don't give up. In this article we will tell you how to repair the device yourself.
In order to repair the LED processor with your own hands, you must confidently hold a multimeter (in the picture below) and a soldering iron in your hands. This is necessary in order to be able to determine the cause of the breakdown, and, in fact, eventually eliminate it, bringing the device back to life.
So, first of all, you need to determine the cause of the malfunction of your device. If the spotlight turns on, but when it is on does not burn evenly, but flickers and blinks, the current-limiting capacitor C1 is probably out of order. Many Chinese manufacturers sin by using a current-limiting capacitor that is not suitable for the driver in terms of parameters, trying to achieve maximum brightness from a not very powerful floodlight. A current limiting capacitor of 400 volts rated operating voltage is fine.
Another common cause may be the failure of the power supply. There are two ways out of the situation - contact an electronics store, where they will help you choose a suitable power supply unit (its characteristics are indicated on it, therefore, it is advisable to disassemble the spotlight and take the unit with you), or select a power supply unit (it can come from a scanner or printer).
The second option is possible, of course, only if you suddenly have unnecessary and non-working office equipment lying around, which can serve as a power supply donor. Check the power supplies so that they are similar in parameters. An exact match is not required, but the parameters should not diverge much. As mentioned earlier, if you have the skills to use tools and an understanding of electronics, you can easily change the power supply yourself.
If a low-power floodlight needs repair, it is likely that it may not have its own power supply, and the LED driver performs the function of changing the currents in it. Since the LED cannot be powered directly from the mains, requiring an alternating current that differs from what the mains can offer it, a driver is used in the floodlight device that takes into account the spread of the LED characteristics depending on the operating temperature and time, correcting the current supplied to the LED at the output ... It is this driver that can fail.
To replace it, it will be necessary to disassemble the LED floodlight and find out the driver marking in order to buy or order a replacement. If you are a confident user of a power tool, you can find the failed driver element and unsolder it and replace it. If you are repairing a DIY LED floodlight, most likely it will be easy enough for you to find the problem in the driver or find a similar driver and replace it. It will definitely be cheaper than buying or assembling a new floodlight from scratch.
Another option for the failure of the design of your LED floodlight, in addition to a malfunction of the driver, power supply or other small elements involved in the current conversion process, may be the burnout of the LED matrix itself. In case of failure of the LED itself, it is necessary to find and purchase a diode of similar characteristics. After disassembling the spotlight, you will need to carefully uninstall the burned-out matrix by unscrewing the four fastening screws and unsoldering the conductive elements. Then you will need to evenly and carefully apply a layer of thermal paste to the new diode, solder the current-carrying elements and carefully screw the matrix. It should be noted that the shape of the matrix must remain intact, that is, it is advisable to use the same screws that were used initially. They should not have tapered heads, as when using them, if you tighten them with a little more force, they can damage the die, and all your work will be for nothing.
To repair an LED spotlight yourself, you must at least have a good command of working with a soldering iron, testers and a multimeter, as well as understand the circuits or be able to read them in order to find the cause of the malfunction, evaporate the faulty element and replace it.
If a driver or a power supply unit is out of order in your spotlight, you can pick up a replacement and bring the lighting fixture back to life. Just as with the driver, replacement can be done with an LED matrix - just buy an analogue with similar characteristics. If for some reason after your manipulations the device did not work, it probably makes sense to purchase a new one. But if you are confident in your abilities, you can always assemble an LED floodlight with your own hands - it will be easier to repair it in the future, or replace some elements, constantly extending the life of the device.
