DIY LED spotlight driver repair

Repair of LED floodlights. Shown is a very budget do-it-yourself repair option

LED floodlight by installing LED COB chip. The LED COB chip has a built-in driver for power supply from a 220 Volt network. COB (Chip On Board) technology is widely used in the production of LEDs by placing a plurality of LED crystals on the chip board, which allows to obtain diffused light from a group of powerful light-emitting SMD elements. Modern miniaturization makes it possible to place on the same board the SMD elements of the driver for the converter of the 220 V mains voltage to the constant supply voltage of 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 you not to think about looking for the causes of the malfunction. For details of the repair scheme for a spotlight with the installation of a LED COB chip, see below with photo and video illustrations.

The original LED floodlight, having worked for almost four years, and after a month of unstable work finally went out. Diagnostics by external examination did not reveal a specific breakdown. No damage was found on driver parts.

Inspection of the driver board of the LED floodlight

Inspection of LED driver parts

However, the body of the searchlight was made soundly and the issue of repair was raised. In the process of selecting parts, an offer was found for the sale of a LED COB chip with a built-in driver for power supply from a 220 Volt network. The searchlight was supposed to be installed in a specific place, which required only local lighting. The LED COB chip was chosen with a power of only 5 watts. The chip with the driver was ordered in the online store using the link https://ali.pub/1t91gm... There you can also buy chips of higher power.

5 Watt LED COB chip

Since the 5 Watt chip, in view of its miniature size, does not have mounting holes, a heat-conducting glue is needed to install it, you can buy it at the following link https://ali.pub/1wkjbg... Repair with the installation of a LED COB chip is not difficult, but requires care and attention.

We disassemble the spotlight. Remove the cover of the LED driver compartment and disassemble the driver case.

LED floodlight driver compartment

Removing the glass frame of the LED floodlight

Removing the reflector of the LED floodlight

Defect of fixing the LED

Removing the driver and LED

Connecting the power wires

LED COB Chip Installation Location

Bonding LED COB Chip

Refinement of the reflector of the LED floodlight

Soldering the power wires of the LED COB chip

Installing the reflector on the LED COB chip

The floodlight is installed in a predetermined place and is controlled by a volumetric motion sensor. The cost of repairing a 5W LED COB chip in detail is ridiculous. See the result of the repair work on the spotlight on the video.

For normal operation of the chip, as for all LEDs, a gentle temperature regime is required. The chip temperature was monitored during long-term operation of the floodlight at room temperature. The chip only warmed up to 30 ° C.

LED COB chip with built-in 220V power supply driver is a good alternative to replacing the driver or LED when repairing LED floodlights.

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.

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 resistance parameters 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 luminous 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 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:

1. 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.
2. The body of the device, as well as the LED matrix, are checked for mechanical damage (deformation, chips, cracks).
3. 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.

1. 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.
2. 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:

1. When replacing a matrix, be sure to pay attention to the polarity.
2. It is imperative to remove cured heat transfer paste underneath the die.
3. Degrease the surface with alcohol.
4. 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.