Backlight lamps for RK monitors characteristics. Reprocessing of the monitor's backlight lamps into light-emitting strips. Scheme of a LED backlight monitor with a built-in dimer
In this material, the author continues the topic, published in the article - he describes the diagnostics of inverters for electroluminescent cold cathode lamps (CCFL lamps). The basic electrical circuits of all inverters, which are discussed in the statistics, are shown in.
Correct diagnosis of the malfunction will significantly reduce the time required for repairs and costs. The main problem that arises when diagnosing the lighting system is to determine what is faulty: the lighting lamp or the inverter. Practice shows that the malfunction of CCFL lamps manifests itself in the following way:
The screen is filled with red ashes;
When you turn on the laptop, the color of the screen turns dark blue, and then becomes normal;
The backlit panel (all images) glows in time with the changing brightness of the plot;
The backlight panel begins to glow and then turns off.
Failure of the lamps during such manifestations is confirmed in approximately half of the cases; in other cases it is necessary to switch to lower methods.
Structurally, the inverter board and lighting lamps are usually located under the front cover of the laptop screen. First of all, what to reconfigure: the power supply problems are not related to malfunctions of the laptop’s motherboard. When connected external devices- monitor, TV, projector, image, then, most likely, the lighting system of the laptop is faulty.
To repair the inverter or the switching system, the minimum required equipment at the work station is a multimeter, an oscilloscope and an independent device with an adjustable constant voltage of 1.5 to 30 In the stroumovim zakhistom (1 A), and also a CCFL lamp.
To prevent the insertion of a faulty lamp when repairing an inverter, use equivalent measures. It is important to connect a valid lamp to the test inverter. If there is no such thing, then a resistor with a nominal value of 100...130 kOhm with a voltage of 2...5 W is connected to the output socket of the inverter (as inverter manufacturers recommend). The resistor is selected according to the required secondary voltage at the output the call of the bell. For equivalent value, you can also use a high-voltage ceramic capacitor with a capacity of 20...200 pF and an operating voltage of no less than 2 kV. The viscosity of the capacitor when monitoring the inverter in operating mode is shorter, however, problems may arise when starting the inverter controller. The inverter can be respected for the presence of a stable sinusoidal voltage at the equivalent of voltage.
Replacing the lamp is of particular importance and ensures the cleanliness of the area. Work is carried out using mittens. In some cases, if external disassembly of the matrix is required, this operation is carried out in “clean” rooms and special clothing.
Malfunctions of the inode supply are associated with damaged contact in the welding (soldering) area of the inverter and the lamp electrode. And here it is possible to update the effectiveness of the switching system. For which it is necessary to remove the insulating tube (humic tip) from a faulty CCFL lamp. It is better to weld or solder using hard solder and a gas soldering iron, which creates high temperature the place is having a blast. The tube, which has been coated with the wire in advance, is carefully pulled on the soldering area and the lamp is ready for use.
Malfunctions and repair of SAMSUNG laptop inverter
To access the inverter and lamp board, remove the decorative cover from the RC panel of the laptop, connect the cable to the inverter that connects it to motherboard, and lamp connection cable.
The screen does not light up
Check the quality of the inverter elements with a second look. In the event of a malfunction of the power elements and, first of all, the transformer, it results in a darkening of the housing, insulation that has been burnt, darkening, and the destruction of the circuit board underneath it.
Check the presence of voltage on the CN1 connector (Fig. 3c): +12 on pins 1-2, inverter voltage on pin 4 and brightness voltage on pin 3.
In normal mode, when video card drivers are required, there is no voltage on pin 4 of CN1. The inverter switches on automatically when power supply is applied. The brightness voltage (contact 3) is no less than 0.5...2 tbsp.
Check the voltage on the emitter of transistor Q4, and whenever possible, check the ignitors F1, TF1, as well as transistors Q7 and Q5.
Check the validity of transistors Q1, Q2. These digital transistors are of the KST1623 type, they are produced in the L4 housing, they can be replaced with an analogue of the BSS67R type. If transistor Q1 goes wrong, you need to replace it. When leaving the operation of transistor Q2, check the serviceability of transistor Q7 and operational booster U1A.
If the fault lock F1 is in good working order, and TF1 (self-recovery lock) is faulty, before replacing it, check the serviceability of transistor Q4 and zener diode D2.
Check the brightness control voltage on pin 3 of CN1. For diagnostics, apply a voltage of approximately 3 volts from the external circuit to pin 3. If the screen lights up, then the reason is that the motherboard of the laptop is faulty. In this type, the screen switch can be connected to the primus by supplying voltage from a resistor (80 kOhm at the upper arm (up to +5 V), and 40 kOhm at the lower arm), connected to the +5 V bus. If the screen does not light up, Indicate the validity of transistor Q8 .
The light switches off 1-2 seconds after being activated operating system
We first check the validity of CCFL lamps. Connect the oscilloscope to pin 1 CN2 (div. Fig. 3c) and equivalent voltage. If at this ("hot") contact of the CN1 connector there is a sinusoidal voltage with an amplitude of 500...700 V and a frequency of 60...70 kHz, then the inverter is normal and the switching on of the switch may be due to a malfunction of the lamp or damaged contact between inverter wire and lamp electrode. It all comes down to disassembling the laptop and removing the lamp. Keep an eye on the shape and the level of voltage on an equivalent stretch of at least 10 lines, replace the faulty lamp. If there is no voltage and this type of problem is present, the malfunction is due to internal problems in the inverter.
Check the lance of the turnip link. When the inverter is turned on at the cold contact of the lamp, the oscilloscope registers a signal (its form does not have any significance) with an amplitude of at least 1.5 V, and on Viv. 6 U1 the voltage becomes unchanged ( constant voltage, which is measured with a multimeter), check the validity of the diode assemblies D4, D5 (they can be replaced with either the same size or two adjacent diodes type BAV99 in SMD packages). If the connections D4, D5 and resistor R14 (1 kOhm) are correct, then the U1 microcircuit is faulty.
Check the precision stabilizer U2 (TL341). If you are in reference, then on Viv. 5 U1 has a constant voltage of 1.5 V. In addition, this inverter protection line is connected to brightness regulation and a voltage protection circuit. To determine which of these lights is faulty, turn them off sequentially (rather than simultaneously) for every hour. First turn on the circuit breaker D3 R3 R4, then the brightness control transistor Q8. If these lamps work stably when these lamps are turned on, then there is a problem with these lamps.
Check the presence of contact at the CN2 connector. Once there is a visible burn to the contact, it is renewed. If the contact does not respond suspiciously, connect the equivalent request. Check the formation of the lancet signal to the protection signal in the direction of D3 C3 C4 D5. Protection can be caused by overheating of transformer T1, malfunction (voltage) of transistors Q5, Q6.
Malfunctions and repair of inverter based on MP1101 controller
The screen does not light up
Check the presence of voltage on pins 4 (VCC), 2 (Enable) of the JP1 connector (Fig. 4 c). When the operating voltage is 12 V, the turn-on voltage of the Enable inverter is no less than 1.5 V. The presence of the Enable voltage indicates a malfunction of the laptop’s motherboard, which is greater than all video cards. The presence of voltage 12 on the JP1 connector when the cable that connects the inverter to the motherboard is connected indicates a malfunction of the motherboard. There is a voltage of 12 V on the socket, and on the Viv. 6 U1 is equal to zero, check the serviceability of the filter capacitors, the lock F1 and the controller U1.
Check the voltage of the inverter on Viv. 4 U1. Every day, check its presence on the contact of the connector connected to the inverter board. If the voltage is during the day, check the laptop circuit. The inverter switch-on voltage may be due to either a malfunction of U1 or a cut or cold solder of the REN1 resistor (on the inverter board based on the MP1011 controller there is no radio element value, so refer to Fig. 4c. ). To eliminate this problem, simply solder the SMD resistor REN1. Check the serviceability of transformer T1 (greater), connector CON2 and wires.
The light switches on for 1-2 seconds and goes out
We must first check the elements of the lance of the gateway link D2 (a, b) CSENSE RSENSE. Diody is verified on the spot or tried. Check the validity of the lamp (wonderful thing). Connect the equivalent value. Connect the oscilloscope to the Lamp+ connector (Fig. 4 st). If the operating system on which the sine-wave voltage is 500...700 V is initially affected, then the main inverter board is serviceable and the lamp needs to be replaced.
The reason for the missing light may be due to the incorrect operation of the gate unit. As soon as the screen on Viv is darkened. 2 for the current hour there is a positive voltage of approximately 0.5 V, otherwise the lamps go out, then replace the MP1011 controller. If the gate voltage is less than 0.1, check all the elements in the gate coil: D2, RSENSE, CSENSE.
When the inverter is turned on, the oscilloscope detects a signal with an amplitude greater than 0.5 V on a “cold” output lamp, and on the Viv. 2 U1 the voltage is no longer constant (constant voltage, which can be measured with a multimeter), check the validity of the same assembly D2, it can be replaced with two diodes of type BAV99. If the reference diodes and resistor RSENSE (140 Ohm) are not broken (cold soldering), then the MP1011 controller is faulty.
The backlight goes off after a few seconds or even
In this case, transformer T1, capacitor CSER (per turn), and lamp connection wires are checked for possible damage to the insulation and damage to metal objects in the housing.
Malfunctions of inverters based on the OZ9938 controller
The screen does not light up
Check the identity of the victim F1 (Fig. 5 c). If it is faulty, then first replace it, check the serviceability of transformer T1 for external signs (darkness, insulation, burnt out, missing board). Then check for breakdown of the transistor stack of field-effect transistors U1. If the OZ9938 controller operates alongside a parametric stabilizer (not shown on the diagram), check the validity of its elements.
If the inverter circuit is correct and at the output of transformer 7 T1 there is a sinusoidal voltage of 550 V with a frequency of 55 kHz, then check the validity of the SG connector.
Check the presence of switching voltage (not less than 1) on pin 6 of the CN2 connector. If the voltage is lower than normal, the voltage is turned off. 10 controllers on the ENA bus. If the voltage on contact 6 increases to 2, check capacitor C18 or replace controller U2. If the voltage on pin 6 is low, the reason is the laptop’s motherboard. You can get out of the situation by applying voltage to 2 outputs of the external circuit breaker.
Check the voltage on the Viv. 4 U2, if it is less than 0.1, then check the controller, laptop board and capacitor C10. Check the voltage on the Viv. 11 U2, which in normal mode should be greater than 3, when the voltage decreases, check C14, and solder resistor R9. If the reference elements are faulty, replace the controller. The light switches on for 1-2 seconds and goes out
This defect may be caused by a malfunction of the lamp or its connection. If the lamp is OK, check the turntable link D1 C22. If there is no signal to turn on the inverter, the voltage at output 6 U2 is greater than 1, then the microcircuit is faulty and must be replaced. What is the voltage on the viv. 6 is less than 0.7, the lamp is working, and the backlight turns on for a few seconds, check the lance to ensure that D2 R5 R3 is re-engineered. What is the voltage on the viv. 6 when the inverter is turned on, the voltage increases and at one point the voltage moves 3 and when the lamps turn on, the reason is the output stage of the inverter. This may result in a lamp malfunction (problems associated with startup failures if startup of the lamp is delayed). In addition, reversal may be related to us in advance through the presence of short-circuited turns of the transformer windings.
What is the voltage on the viv. 6 does not exceed 3, if the lamp turns on, then check the presence of voltage no more than 3 on the Viv. 7 U2. If the voltage is below this level, check capacitor C8 (vitik) or replace controller U2.
The backlight is wetted through a splint of quills after insertion
Check the lantsyugi zakhistu vid navantazhenya D2 C2 C5. Check the validity of transformer T1 (wonderful). Sometimes a malfunction appears after ten hours, during which time the transformer heats up (above 50 ° C), it is necessary to replace it. Check the validity of the transistor unit U1 (can be determined by its operating temperature). As a rule, this problem occurs during the “freezing” of the suspected elements with Freeze gel. Whenever the light switches on unstably, check the correctness of the lamp and the socket of its connection.
Malfunctions of inverters based on the OZ960 controller
The screen does not light up
For inverters of the AMBIT and KUBNKM types (div. Fig. 6 c), you can also observe the indicator on the front panel. For which type, disassemble the laptop and check the presence of +12 V voltage (for KUBNKM inverters, the input connector J1 (CN1) is 20-pin, the live voltage is on the 4 outermost contacts, and for AMBIT inverters the connector is 16-pin, and life voltage be on the 2 outermost contacts). If the driver F1 is faulty, check the transistor assemblies U1, U3. Verify the presence of life stress on life. 5 controllers OZ960 (U2). This voltage, in addition to standard inverter circuits (Fig. 6 st.), goes to contact 1 of J1 through the stabilizer on transistor Q1 (marked on the board). In AMBIT inverters, controller U2 is located at pin 4 of J1. The live voltage at the outlet itself can be daily due to a malfunction of the laptop's power supply or through a short circuit to ground on the Viv. 5 U2. For diagnostics, connect the SVDC line to connector J1 and if the voltage on the bus appears, then the inverter is faulty.
Check the presence of voltage on the ENA controller on Viv. 3 U2, but not less than 2 V. In the KUBNKM inverter, the controller’s turn-on voltage goes to transistor Q1 (from which the supply voltage is taken) and through a 10 kOhm resistor. Other modifications of inverters based on the OZ960 controller may also have their own characteristics and advantages compared to standard circuits, but the method for detecting malfunctions is the same.
If the LEDs on the laptop keyboard panel are glowing, there is no illumination of the screen, and the voltage is overloaded, then check the correctness of the assembly of field-effect transistors U1, U3, as well as the stabilizer in D1, D2 (4.7 V).
When the laptop is turned on, use an oscilloscope to monitor the presence of direct pulses on the screen. 11-12 and 19-20 U2. If there are no pulses and the assembly of U1, U3 is correct, then check the presence of a voltage of 2.5 on the Viv. 7 U2. If it is missing or underestimated, check the C13 and replace the controller. Check the presence of a sinusoidal signal on the IV. 18 U2 with a frequency of 50.60 kHz. If the frequency significantly increases from the nominal one or the signal is completely absent, check elements C5, R4.
The frequency of switching may be related to the frequency of (lower) voltage on the TV. 14 controllers. If the voltage on the output is less than 1, supply voltage 3 from the external source. If the screen lights up, the problem is related to the voltage supply to the brightness control of the laptop board. In this case, you can apply voltage to the brightness control input from pin 1 of J1 through a resistive connector, but in this case you need to turn it off so that the brightness will not be regulated
The backlight flickers 1-2 seconds after the laptop is plugged in
Check the reference lamp of the backlight (an amazing method for checking the lamp). They are connected by an oscilloscope to the “hot” (upper one behind the diagram in Fig. 6 c) transformer T1. When you turn on the laptop, this output shows a voltage with a sinusoidal frequency of 55...60 kHz, and you immediately stop checking the validity of transformer T1. Then check the serviceability of the transistor folds U1, U2 on the turn: measure with an ohmmeter the support between the turn and the drain and if you show the end values at between 100 kOhm, then replace the fold. Check the validity of capacitor C4 for turn (ESR).
Check the presence of tension in the ligament on the IV. 8 of the controller, it may overestimate 1.25 V. If the voltage is lower than this value, check one assembly of CR1, and also solder the resistor R8. If there is no result, replace controller U2.
The backlight goes off after a few seconds or even
And here they check the overvoltage protection circuit. Connect them to the main circuit (it is enough to solder one folded CR2). When the laptop is turned on, check the presence of voltage on the screen. 2 controllers (may be no more than 1 V). If this voltage exceeds the values of the rhubarb, check the limit value of 2.5 on the Viv. 7. If there is no voltage or the voltage is too low, replace the controller. What is the voltage on the viv. 2 is normal, and when the circuits are connected, the voltage rises above 2 or changes over time, check the serviceability of the transformer, capacitors C7, C11, diode assembly CR2. You can replace the transformer with another type of inverter (this circuit is insensitive to the type of transformer), the only thing that needs to be adjusted is the return voltage coming from the cold end of the lamp (selecting resistor R8).
In an AMBIT type inverter, which uses an OZ979 microcircuit to power the keyboard's LEDs, you can try updating the screen illumination behind the clock circuit. Turn on the lamps and on the back side of the RKI matrix, fasten (stick) lines of LEDs to the top and bottom of the screen in a row of 3 pieces. in 5 lines, the first LED is connected to 3 OZ979, and the remaining one is connected to the housing. This method is suitable for small screens of 10-12 inches.
You can speed up the inverter circuit based on OZ960, after replacing the transformer with capacitor C4, install a double diode in the SMD case and a resistor to suppress it with a nominal value of 50 Ohms. The supports are more accurately selected when the LEDs are installed to ensure normal illumination and proper operation; for normal illumination of a 15-inch display, 16 bright LEDs are sufficient And, for example, FYLS-1206W is white in color. LEDs can be glued to a fluoroplastic strip and connected with thin conductors. In this case, the input voltage on the first LED should not exceed 80 at a flow of 25-50 mA. Set the output through the LEDs to the same value as the interconnect resistor.
Various circuits based on OZ960 are classified as standard, including the naming and modification of circuits electronic components.
Sometimes there is a risk of decreased brightness and insufficient regulation. This is achieved through the lower flow of the gas-discharge lamp through the advancement of the transition support in the place of the contact on the board of the high-voltage winding of the transformer T1 and the ballast capacitor C4. The problem is limited to the soldering of the capacitor fins.
Literature
1. Volodimir Petrov. Repair and maintenance of inverters, lighting lamps, power supply lamps, laptop panels. Repair & Service, 2010, No. 3, p. 37-40.
In this article we will look at how you can self-repair the monitor.
The current RK monitor consists of two boards: a scaler and a life block
Scaler- This board controls the operation of the monitor. Yogo brain. Here the monitor converts the digital signal from the color on the display, and also places it on its own razni adjusting. It houses the processor, flash memory, where the monitor firmware is written, and EEPROM memory, where precise settings are saved.
Living block. This will ensure the life of the monitor. You can also use an inverter for monitors with LCD switches. Monitors with LED backlights do not have an inverter.
The living block for the monitor looks something like this:
And so is substantive humility. In living units for monitors with LCD switches, the high-voltage part can be increased. It's an inverter. About its presence there are signs like “High Voltage” and terminals for connecting lamps. Be careful that the voltage supplied to the lamps is over 1000 Volts! Above all, do not scratch and, moreover, do not lick this part when the monitor is turned on.
Blown capacitors
These, of course, are electrolytic capacitors in the filter unit.
This is one of the most common failures of RC monitors. Resoldering capacitors is easy and simple. Sometimes the boards have non-standard capacitor ratings, for example, 680 or 820 uF x 25 volts. If you have come across capacitors of such a rating that are swollen, and they do not appear at your radio store, do not rush to go around all the radio stores in your area in search of exactly the same rating. It’s just a shame if “it’s not too bad.” That's what some electronics guy will tell you. Kindly set 1000 uF x 25 volts and everything will work fine. You can say more.
Due to the fact that the life unit produces heat during operation, which is incorrectly indicated on the service life of capacitors, be sure to install capacitors marked “105C” on the housing. Also, after re-soldering the capacitors, do not hesitate to check the protector of the secondary lancets, the role of which is often played by a simple SMD resistor with a zero support, size 0805, which is located on the reverse side of the board on the side of the transfer.
Output from the zener diode fret
And one more nuance, at the output of the life block, before the life itself is connected to the scaler, often install an SMD zener diode
In the event that the voltage on the new one exceeds the nominal one, there is a short circuit and thereby turns off our monitor through the lanyards. You can replace it with something that matches the voltage rating. You can vikorista with vysnovki
After everything has been installed and repaired, we check the voltage on the power supply that goes to the scaler. There is all the pressure of signing. Let's reconsider that the stinks are avoided with the multimeter readings.
Problems with the high-voltage part of the life unit (inverter)
If it is possible, then first of all, look for diagrams of the structure that is being repaired. Let's take a look at the high-voltage part of one of the monitors
As you know, the power supply to the burnout monitor's life block means that the power supply between the monitor's power cord wires (input power) at some point becomes very low (short circuit). Here it is close to 50 ohms and less, which, according to Ohm’s law, called for the advancement of the struma in the lancus. Seeing the great power of the stream we have and the burning of the prisoner’s wiring.
Since it is in the metal-glass case, we can insert any kind of holder in the fastening and dial in the 200 Ohm Ohmmeter mode between the pins of the plug. Since we rely on zero and up to 50 ohms, then we look for a broken radio element that can ring to zero or to ground.
Crocs will be like this:
We insert the locker, switch the multimeter to 200 ohms and connect it to the power cord plug. Let's reconfigure that the base is even smaller. We are in no hurry to capture the prisoner.
So, let’s see from the diagram how our radio components can shorten. In the photo you can see the details that need to be checked with colored frames. short circuit at the high voltage part
All these procedures for re-insurance of the support are carried out in order to repair the over-insurance parts one by one. This is repeated and measured again through the support fork. As soon as we remove the high support at the input of the plug, having replaced or removed the defective radio element, you can safely plug the plug into the socket and move on.
There is no monitor backlight
What is the difference between monitors with LCD backlights and monitors with LED backlights? For LCD monitors, we use CCFL lamps for illumination. In Russian, this abbreviation sounds like “cold cathode fluorescent lamp.”
Such lamps are located at the bottom of the display and illuminate the images.
LED monitors are equipped with light-emitting diodes to illuminate either the sides of the display or behind it.
Now all manufacturers of monitors and TVs have switched to LED backlighting, as it saves energy at half the rate and is much more durable than LCD backlighting.
Since there is no backlight, on the right there can be either CCFL lamps or LED strips. If they don’t burn, the images will be so dark that nothing will be visible on the screen. Only a respectful glance at the darkened monitor under the lighting can show that the image is still there. If the image is blank, then first look at the monitor switching on under a stream of light. If the image is at least a little visible, then go ahead and change the lamps, or on the right in the inverter.
Monitor backlight disappears
Our monitor freezes, runs for 5-10 seconds and goes off. This means that one of the CCFL lamps in the display backlight has become unusable. In front of this, part of the screen can also blink a little. The inverter in this case is subject to protection, which manifests itself in automatic connection Monitor backlight.
In order to be able to check the lamps and turn off the defective ones, you need to buy a high-voltage capacitor at a radio store. 27 picofarads x 3 kilovolts for 17-inch diagonal monitors, 47 pf for a 19-inch monitor and 68 pf for a 22-inch monitor.
This capacitor must be soldered to the contacts of the connector to which the backlight lamp is connected. The lamp itself, obviously, needs to be turned on. By connecting the capacitor through the skin connector, we assume that our inverter stops protecting.The monitor asks if it wants to be a little dark.
Of course, you rarely want to be so timid. The trick itself is to enable the protection on the PWM microcircuit))). For this we google “remove inverter protection xxxxxxx” Instead of “xxxxxxx” we put the brand of our PWM microcircuit. I suppose I connected the circuit breaker on the monitor with the TL494 PWM microcircuit behind the circuit below, soldering a 10 Kilo Ohm resistor. Monique finishes her work. There is no complaining).
The most common cause of problems with RK monitors is that the matrix comes out of line with the backlight lamps. Just like for phones and small displays on tablets, LED strips are installed; in matrices with a large diagonal, CCFL lamps are installed for these purposes. Essentially, this is the same daylight fluorescent lamp, but with a cold cathode.
It is unacceptable for them to get along without special visible reasons, and turning one lamp out from the fret will trigger the block to shut down and turn on the live monitor.
Light up the lamp that burned out the CCFL in the lighting module.
Getting rid of the old CCFL
The most obvious way to solve the problem is to replace the lamp, otherwise repairs may involve some pitfalls. For example, such a lamp is needed to replace it. Dzherela with other life parameters does not want to accept an inverter, and finding a new analog for the model released 5-6 years ago is problematic.
We have already added the idea of converting the monitor to LED backlighting.
To switch to LED, you will need to use an inverter for CCFL lamps. We will no longer have any hope, as the fragments at its output form a high-voltage, high-frequency signal that is fatal to the LED.
Simply connect the cable to the inverter connector from the main board. On Maybutn we need a rose “dim” for brightening Light-colored lines.
To replace the monitor's lamps with a single line of LEDs, you will need to disable the life driver.
Replacement is carried out in two stages. The first is the installation of CCFL lamps and the power inverter, the second is the installation of the LED strip, the power driver and their connections. As a LED driver, you can use 220V and 12V models so that they fit the dimensions.
As an equivalent of CCFL, the most suitable lines are those with 120 diodes per meter. It was not possible to know such a line of the same width as 90 diodes per meter.
The stitching will be a neutral white color, otherwise the color match is guaranteed. When choosing a light-colored line for your monitor, please pay special attention. Read the report about the color of lamps.
When replacing the lamp, it is not easy to get rid of too much brightness, because high-voltage LEDs have thermal imaging values that will not appear on the matrix itself.
How to replace the monitor's LED light
Dismantling the body will become the most difficult and delicate task for us.
Any careless disruption could result from shaving the train or damaging the matrix. It is not easy to disassemble the housing when the power supply is turned on; a kilovolt voltage is generated at the inverter output. Break it into the fire block or the matrix is guaranteed to burn all the blocks.
Besides, replacing the backlight of a LED monitor with your own hands is easy.
The electronic filling consists of three blocks:
- Living block;
- image display block;
- lamp inverter unit.
Ensure that the inverter unit is closed with a dry casing.
The LED strip installed instead of the monitor backlight lamps must match the width of the lamp flutes as much as possible, otherwise the backlight will be uneven.
If you have selected a 12V LED driver, make sure that the power supply unit outputs such voltage. You can first find out the point on the board where the voltage is 12V, if you connect the driver to it, you can then click on the “sap” voltage and unstable robot electronics.
Scheme of a dimmed LED driver
As you already guessed, to replace CCFL with LED in the monitor you will have to install the LED strip driver.
You can use the simplest PWM controller to dim the brightness of the light yourself using the N555 microcircuit.
Scheme of a LED backlight monitor with a built-in dimer
The signal generator that dims is collected on the NE555 pulse generator, the peculiarity of the microcircuit is the ability to change the frequency and pulse spacing. The exchange resistor in this circuit contributes to the voltage.
The advantages of such brightness control circuits are low thermal output and a wide range of signals, and limited mechanical regulation. This circuit is needed because there is a program dimer on the lamp inverter board. This LED lighting circuit is universal and suitable for screens of any kind.
Scheme for external dimming
This is a copy of the output stage of the front circuit. If the signal from the dimmed output is insufficient for the correct operation of the field-effect transistor, an additional low-power transistor switch can be installed in front of the gate, which will play the role of a voltage switch.
And this scheme allows for the brightness of the stitches through the standard channel. Please note that the dimming depth for ccfl lamps is less than that of LEDs, so in this scheme the brightness range will be less than in the first option.
On many Toshiba, JVS, BenQ devices, PWM is software, if the inverter receives a signal for increasing or changing the voltage, and the dimming signal is generated by the controller of the inverter itself. For Samsung and LG, all models have a “dim” output, which is suitable for controlling the brightness of the monitor backlight.
Replacing ccfl with LED on the monitor allows you to significantly reduce the cost of installing a new lamp. Please note that at minimum prices, lamps cost 3-5 dollars, and a half-meter of LED strip at a time from the driver will cost you less than a dollar.
I would also like to ask you to contact the “PMS” contact, which goes from the head board to the life block or, by extension, from the life block to the head board. Can't you figure out his role?
I don’t need to bother, because I also want to get into it. I am mounting a monitor on a swivel bracket and want to power it from a standard TFX housing unit in a housing in which it will be assembled new computer for dads (with not even new components, with DDR3L memory and Intel processor 3rd generation :). Today I conducted an experiment by supplying 5V, 12V and minus from the flop socket to the disk drive from the computer's life block. The monitor normally requested and then turned on and beeped at the power button (I note that the PMS sends a signal to the life block about the shutdown of the inverter or the inverter and the head board at the same time). We simply hang the monitor above the bedside table and place it there, so it is much easier to power up this type of life block, and moreover, by introducing a two-phase switch into the life block, which simultaneously switches on zero and phase (then the computer 'Your no longer needs to imitate sockets). And if you run a 220V cord directly to the monitor, then there are more wires, plus more hassle with switching on / plugging in, and the CCD of the living unit will not be much lower (the total energy accumulated during the life of the computer living unit will decrease ~5-10 V t) . Life unit with "GOLD" certificate, Sea Sonic Electronics SSP-300TGS Active PFC 300W. Therefore, I need to know how to trigger the “PMS” signal, since it won’t be critical if it is present on the monitor’s live block?
I also conducted an experiment with “PMS” today. This contact is supplied with 2794 volts and only when the monitor is running. If the monitor goes to sleep or the button on the front panel blinks, then “PMS” immediately drops to zero. And so it turned out that the first cat sees 5 volts 1.5 amperes, and the other sees 12 volts 1.2 amperes (for powering the headplate) and 12 volts 3 amperes (for powering the inverter). So, whenever the monitor is turned on or off, 12 volts disappear from both lines, and 5 volts are supplied for the entire hour while the monitor is plugged into the outlet and the main power supply supplies 220 volts to the power supply unit (perhaps 5 volts goes to the head board and suddenly the stench is needed to display the monitor in the wash mode.
So it’s better for all the “PMS” to still come from the head pay to the living block and it is necessary to launch a high-pressure cat, but you still want to know the expert’s opinion, so I judge only in practice and from logical assumptions.
And if it is possible, then I have three more lies before you.
1) You can’t see the 12 volts coming from the life block to the head board, it’s okay that 12 volts will be supplied continuously during the hour of sleep or when the monitor is turned off through the button on the head panel. As I have already written above, 5 volts are supplied to the power supply unit continuously, and the 12 volt axis is supplied only during the operation of the monitor. I just want to make sure that 12 volts does not damage the main board during the hour of sleep and when the monitor is on.
2) Always eating system unit, I want to implement LED switching with brightness control behind an additional changeable support in order to eliminate the PWM of the diodes at low brightness (interference). I understand that the rooms will heat up more, resulting in CCD (slight increase in energy absorption), but the health of the eyes is more important. I myself don’t know how to properly unpack the changeable resistor that needs to be placed in the lance due to the tightness. According to the printer, the accumulated energy of the stitch is 9.6 watts per meter. The stitches are cut at a distance of 5 cm, and my matrix requires two cuttings of 45 cm, for a total of 90 cm. And according to the manufacturer’s claim (which I don’t even trust) it works at 12 volts 800 milliamperes per meter , minus 10 % = 720 milliamps. It would be better to use a full supply of power, preferably 2-3 amperes. I would also like to install an additionally variable support in the lance, so that at maximum brightness (where the changeable support feeds the food directly), the output would not be 12 volts, but 10.5 - 11 volts, no more. It is necessary that the LEDs do not overheat at maximum brightness, and also increase the term of their service, so that the next time I disassemble the monitor and matrix box, I am still satisfied.
If it’s not easy, then write the number or model (I don’t know which is correct) of the replacement support (needs a handle, like a tensioner) acoustic systems, in addition, in the back of the monitor there is a place where you can display the name) and by how many ohms (namely ohms) and watts take a “simple” operation, which is sufficiently reduced in voltage from 12-volt to 10- 11 volts.
3) It is also necessary to know the location in the main board where you can get 12 volts for the power supply, so that the power supply disappears when the monitor is turned off from the switch button and to sleep mode. I myself can use a tester to find out 12 volts, which disappear when the monitor is turned on and asleep, but I’m afraid that the stench will pass through any resistor or transistor, which can burn out due to the additional supply of 0.7-.08 amperes.
For many years now I have been choosing the most compact computer using standard components (a standard living unit, a standard motherboard, processor, VP memory, notebook visibility DVD driveє). Having installed the "RESET" button on the peak, which rejects the indicators, replacing the poor black indicator of the computer with a warm orange one, installing the DVD drive (so that there is no noise unnecessarily when the computer is turned on) and powering up the speakers, and also attaching to the peak there is a booster and a tension regulator. It was impossible to ensure the arrival of the anti-filter filters on the housing and the housing unit and the 6-pin connector to remove the speakers from the housing and indicate their operation. I plan to screw the speakers to the bottom of the monitor body, and display their indicators on the bottom of the speaker body (at both times the lower plexiglass will light up). Already quiet, that I had lost a little hemorrhoids before the completion of this Frankenstein, and then they called me and said that the monitor had stopped working. The delay was very strong: (
Therefore, I want to do everything as reliably as possible, so that it works for a long time and does not cause any more trouble, at least 10 o_o.
P.S.
Thank you for the poor food, I’m just afraid I’ll burn the monitor’s main board through unknown means. Doctors, that this model has not been released for more than 10 years (and as I have already written, there are no alternatives to it, from the current only two models on IPS matrices, it’s been a long time since you’ve been paying for VA, especially for PVA), and it’s practically impossible to buy the same used one from a good company (in Moscow and St. Petersburg they rarely appear for sale). If you buy it remotely, you will be able to see the darkness or stains of the matrix, as well as the bits or pixels that burned. I Kolya, by swimming through the AVITO OTH 2190UXP, seller of PITERA, PITERA, ShO Matritsa in Ideal, and if the Monitor was a mentor, whistled at the nyo lamp, they didn’t get into the nyoye, I did not manage to the nyoye) , I took off two dead pixels(Thankfully, although the pixels are not in the center of the screen and on the VA matrix they are not so noticeable, their fathers do not mark them).
Apparently, today's RK monitors work "on the transmission" of light - as the image on the matrix is illuminated from behind, the light passing through the matrix and light filters forms the image. As the backlight tends to shine in the brightest part of the white light, the matrix, by its light transmittance, is more representative of the dark eyepieces.
Traditionally, fluorescent lamps with a cold cathode or CCFL – Cold Cathode Fluorescent Lamp were used for this purpose. These lamps are made of glass tubes with a diameter of 2-3 mm, the inner surface of which is coated with a phosphor. The tubes are filled with mercury vapor. When gas passes through an electric discharge, vibration occurs, which causes the phosphor to light. For the operation of such a lamp, a high Voltage change- Close to 1500 V with a frequency of approximately 40-50 kHz.
The greatest number of malfunctions of rare-crystal panels can be traced to the output of the switch or inverter - a device that converts the constant voltage (12-18 V, depending on the monitor’s operation) into spring for robotic lamp. This appears in a sharply reduced brightness of the screen, from one of the edges, or when the backlight is turned on - in which case the image on the screen is less visible.
In case of such problems, corporate services “rejoice” in replacing the entire panel, especially in some laptop panels. It can be expensive, but if you have a monitor, it’s easier to buy a new one. Nowadays, there are not only branded services in the world, but also a number of “smart people” who have mastered the operation of replacing backlight lamps and inverters.
Replacing the backlight lamp is a simple operation, and is carried out structurally in many monitors. Although I haven’t read Igor Pichugin on RadioKotya, I’ll make a short introduction to it.
The lamps are mounted on either side of the display near the “pencil case”. To remove the pencil case, you need to dismantle the RK panel in order to remove the metal casing and panel. A thin (about 0.5-1 mm) control board is mounted behind the panel, connected to the matrix itself with a series of cables. To remove the rare-crystalline screen, you need to carefully glue it (do not cut it every time! It is impossible to repair damaged data lines on cable cables) I'll dry up the spit.
To demonstrate the “classic” backlight technology, I used a LG Flatron L1970H RC monitor.
Disassembling the monitor will begin with dismantling the stand. It is necessary to remove the plastic casing from the back that covers the mounting of the light and the cables from the connectors on the stand.
Having taken the stand, remove the RC module from the housing. The front frame is attached with clips and is easily attached to the rear part of the body.
The RK module is covered with a metal casing. Through the opening you can see the inverter transformers with dirty inscriptions.
We tighten the screws to secure the casing.
Now you can clearly examine the ceramic electronics board of the monitor and the connections in front of the inverter block.
The electronics board is connected with a braided harness from the PK-matrix decoder, covered with thin self-adhesive adhesive.
The decoder is connected to the matrix using small thin cables. If you happen to remove the panel, it is impossible to renew the data lines above the very carefully, at which point the matrix will have to be thrown out.
The inverter mounted behind the monitor can often be replaced with a similar one. It is enough to know the voltage and capacity of the lamps. In addition, the inverter in monitors is great and easy to repair.
The lamps are connected to the inverter using standard connectors.
On this monitor, the pencil cases with lamps can be removed without disassembling the panel. You just need to tighten the screw.
…and stick out the pencil case.
The lamps are mounted in two pencil cases. The sign of an “old” lamp is black rings near the cathodes. Lamps that have burned out have a much broader and darker smell.
I needed the lamps badly. They brought in a Fujitsu-Siemens Amilo M7800 laptop with a diagnosis of “even darker than the image on the screen.” U corporate service They asked for unrealistic pennies for the repairs - they decided to change the matrix. I just read the article on “cat” and was about to try replacing the lamp.
To access the PK panel, we first need to remove its frame. Be sure to be attached to clamps, but in some laptop models they may be secured under rubber screw plugs.
At the bottom of the laptop's PC screen, between the hinges, there is an inverter in a dry casing.
It’s hard to verify whether the lamp is really faulty or whether the inverter is “broken.” For this purpose, it is enough to connect a suitable lamp to the inverter.
Laptop inverters are miniaturized and, if they malfunction, require replacement entirely. Replacement with a similar one of a different model is acceptable, since there is a smell both at radio flea markets and at Dealextreme.
When replacing the inverter, it is important to determine how the switching on/off switching and brightness of the light are affected. Determine for which in the loop that goes to the inverter, the DIM signals are transmitted (the brightness control changes between 1 V - the lowest brightness and 3 V - the highest) and ENABLE (0 V - the highest brightness) knena, 3 V - switching on). Call them correct connection This is not necessary for a new inverter, but allows you to save some energy-saving functions.
To replace the lamp we will need to remove the PK panel. You need to tighten the screws that are used to secure the lid of the laptop.
There are straight metals installed on the sides of the panels that need to be removed for further disassembly.
In some cases, the panel of your laptop may have the lamps removed without disassembling the panel as a whole. All you have to do is remove one side of the metal frame and open the plastic case.
It would be better if it was further away, obviously - we go to the radio market, buy the lamp we need and put it on the laptop. The reality turned out to be rather complicated. On Mitino there were no high-voltage lamps, either short (15 mm shorter) or longer (15 mm longer). At the kiosk of the Istok-2 company (a whole stall with radio lamps and all sorts of lighting equipment, located in the far entrance at the end of the basement at the top, glowing like a new Yalinka) we were pleased to vikorist the line from over bright LEDs.
The width of such a line is approximately 3 mm. Groups of 3 pieces are installed on it, the skin depth is about 15 mm. Obviously, you can cut the line of the required amount with pleasant accuracy.
At the same time, with the development of technology for producing high-pressure white light-emitting diodes, light-emitting diodes began to be installed in rare crystal monitors and televisions. In fact, someone can get to the “leading edge” of technology by installing such a switch instead of a burnt-out “lamp”. Having succumbed to the “dzherel” trend, I bought a 300 mm long line for 250 rubles (about the same age as a lamp).
The light line miraculously fit in the middle of the standard pencil case.
To check the LED backlight, it is enough to connect the line inserted into the matrix to the power supply. When turned on, the screen must glow a milky white color.
The folding is carried out in reverse order (c).
In place of the inverter that was thrown out due to lack of need, you can take the circuit onto a circuit board like this:
The resistor values are selected according to the parameters of the DIM and ENABLE signals and the supply voltage.
Finally, I want to say a few words about those for whom light lighting is a guide.
First of all, the luminous range of LEDs does not exactly correspond to the range of lamps. Therefore, on monitors intended for work with graphics, such a replacement may be harmful.
Otherwise, there are “reasonable” inverters, coated with digital signals (call via the I2C bus, and there are also exotic ones). Depending on the availability of the inverter, the PK panel may not stick in.
Thirdly, the head portion of the LED backlight, mounted “on the knee”, is due to the unevenness of the light near the lamp.
It is clear from the photo that the illumination of the lower part of the screen is not evenly balanced, and the lower right corner is dark; unfortunately, the line appears a little short.
In any case, replacing a CCFL lamp with a LED is an accessible and inexpensive way to upgrade RC monitors. Obvious shortcomings cannot be called critical, but in the case of lamps of non-standard sizes, as I can see, this is entirely justified.
Record of publications by Shuri Lyuberetsky. You can deprive your comments there by using your vikorist name from LiveJournal (login via OpenID).