Diy syncmaster 940n monitor repair

In detail: do-it-yourself repair of the syncmaster 940n monitor from a real master for the site my.housecope.com.

Today I will tell you how to repair an inverter with your own hands.

If your monitor has a defect that it turns off after two to three seconds after being turned on, and at the same time the image appears at the time of turning on.

A trance defect can be determined by a device for short-circuited loops, by resistance.

Usually one of the trances breaks. This is, in principle, a disease of monitors.

The simplest option, in the absence of a trance, is to install a new inverter, of which there are many on sale.

A detailed examination revealed a defect in one of the inverter trances. It is easy to check this: you need to try the working candle one by one, first at the exit of the first trance, then the second, and so on alternately. In a non-working trance, the candle will naturally not light up at the moment of switching on.

Without going into details, we solder the transformer of the TMS91429CT inverter so that the protection does not work.

After dismantling the trance, it will look like this:

Then we take a ready-made inverter, for the same number of candles (4 candles), which are freely sold on radio markets, radio stores, etc., such as: model SF - 04S402, dimensions: 135-45 mm. Or something similar, the main thing is to fit the inverter in size.

Next, we supply it with power and control, place it with Velcro in a convenient place. It may be necessary to increase the length of the wires from the lamps to the output of the inverter.

Here are some examples of inverter placement.

And here are examples of ready-made inverters.

It will not be difficult for a person to disassemble.

They brought 2 samsung monitors for repair - 940n and 740n. Most often, these devices have problems with the power supply, but, interestingly, there are several modifications of these same blocks for the forties. Our guys got one modification for both seventeen and nineteen inch models. Accordingly, we will describe the repair of this modification here.

Video (click to play).

The first thing to do is to look at the display from different angles (preferably with the D-SUB cable disconnected, which VGA goes to the video card). If it is noticeable that the inscription “cable not connected“Then this is our patient. The backlight does not work for the patient, and everything else is normal.

Of course, in order to fix this beast, it needs to be disassembled. This is done quite simply - remove the leg and half the body. I half the body using this blue piece that looks like a pick (photo below). You can buy it in most radio markets and one such thing costs about 15 rubles. It is not suitable for any technique, but for both monics, one such was enough for me.

After all the latches are unhooked, put the monitor with the display down and remove the plastic cover. The next step is to remove the casing that protects the wires going to the backlight lamps and unhook the loop 2, circled in blue. The cover can also be removed easily with a small, thin, flat screwdriver. After removing the casing, we detach the wires supplying the backlight (pictured below).

So, I decided to disassemble the monitor. It didn't work right away, because how to understand how he understands is very difficult if you do not know the principle of disassembly. Okay, friends suggested. And I took it apart. How this is done is described here.

Having disassembled the monitor, I removed the built-in power supply board.
Here it is on the panel on which the monitor boards are attached (left board):

After I removed this board, I examined it closely. Almost immediately I noticed that one of the capacitors was slightly swollen:

It can be seen that from above, where there should be a flat round incised surface, it is slightly convex.

So, I evaporated this capacitor and replaced it with another one. Unfortunately, I didn’t have one with the same capacity (1000 uF), so I had to use it with a larger capacity (2000 uF). Here it is, already soldered to the board:

Next, I put the board in place, connected the previously disconnected wires to it, assembled the monitor and connected it to the computer. Included. It works!

So, thank God, the monitor is working! And 3 thousand.rubles remained with me, and did not migrate into the pocket of someone else's uncle. God grant that it will continue to work properly. What I really hope for!

The Samsung SyncMaster 940n monitor received for repair with a malfunction does not turn on, as the owner said that he served faithfully for 13 years, although the production date on the label is May 2007. The monitor itself is well preserved and this was its first renovation. How high quality monitors were made 10 years ago.

Well, I will not delay for a long time and start repairs, in fact, here he is our patient.

When plugged into an outlet, there was no image on the screen and the blue LED on the power button was constantly blinking, which can be assumed that the power supply is faulty. But let's not guess prematurely and from the beginning we will disassemble the monitor.

The monitor can be disassembled very easily, it is enough to unscrew three screws, remove the leg and click on the latch perimeter.

To separate the back cover from the muzzle, I use a medical scalpel, it is very convenient for them to do this. So that the scalpel did not press so hard on my hand, I put heat shrink on it.

We insert the scalpel into the gap between the back cover and the frame of the muzzle and unlatch the latches.

After removing the back cover, disconnect all wires and cables.

Then we remove the casing and turn it over. We unscrew the three screws and remove the insulator.

After removing the power supply board and the inverter, here they are combined, three pregnant capacitors were found, which was suspected at the very beginning.

We solder the unusable capacitors.
For the sake of interest, we check them on ESR Micro. We see that the resistance is 0.63 ohms and the capacitance is 241 microfarads, which means that the capacitor has almost completely lost its capacity, which was originally 1000 microfarads.

We take out a new capacitor and also check it with a device.
Fine! The capacitance in the aisles of the norm is 980 microfarads and esr is 0 ohm, which means that the capacitor is good.

We seal the new capacitors into place.

Capacitors installed 2 pieces 1000 microfarads 25 volts and one 470 for 50 volts.
It remains to assemble the case and put the monitor on a technical run and then give it to the owner.

By the way, this monitor has a slightly defective matrix about which the client immediately warned me. So I won't buy a new monitor.

Thank you for your attention, good luck everyone!

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1 Precautionary measures

1-1-2 Maintaining the LCD Monitor

1-1-3 Fire and electric shock

1-1-4 Product Safety Instructions

1-2 Repairs - Precautions

1-2-1 General Service Precautions

1-3 ESD Protection

1-4 Precautions for Installation

2 Ttechnical specifications

2-2 Specifications for LS15HAA / LS15HAB

2-3 Specifications for LS17HAA / LS17HAB / LS17HAT

2-4 Specifications for LS19HAB / LS19HAT Models

3 Aligning and adjusting the image

3-1 Equipment Required

3-2 Automatic Color Adjustment

3-3 DDC EDID Standard Input Data

3-4 OSD Menu Adjustment When Replacing Panel

3-5 OSD Menu Adjustment When Replacing Backlight

3-6 Service Function Spec.

3-6-1 OSD service function display method

3-6-2; 3-6-3; 3-6-4; How to operate the OSD service function

4 Troubleshooting

4-1 No power (LS15HAA / LS15HAB)

4-2 No power r (LS17HAA / LS17HAB / LS17HAT / LS19HAA / LS19HAT)

4-3 No video signal (analog)

4-4 No video signal (digital)

5 Monitor Disassembly and Parts List

6 List of electronic components

7 Block Diagram

7-3; 7-4 Switching Power Supply (Inverter) Board

8 Wiring diagram

9 Schematic diagram

9-1 Circuit Diagram (15 '' Monitor)

9-2 Circuit diagram (17, 19 inches)

10 Installation and operating instructions

10-5 Attaching fasteners

11 Disassembly and assembly

12 Printed circuit board

13 Description of the circuit

13-1-3; 13-1-4 Inverter power circuit

13-1-5 Inverter protection circuit

13-3; 13-4 Inverter schematic diagram

14 Reference

14-3 Timing table

14-4 Preset Timing Modes

Monitors Samsung SyncMaster 940NA number of the most typical problems in the operation of monitors that sooner or later most computer users have to face are: no signal, problems with image transmission, its complete absence with a power indicator, image color distortion, backlight dimming after a couple of minutes of operation and the appearance this kind of lettering.As a rule, problems with the monitor arise due to incorrect connection, incorrect settings or malfunctions of the video card. The Samsung SyncMaster 940N monitor, a fairly common model, will serve as an example for eliminating such a problem as the lack of a signal and the correct operation of the power indicator. Image - DIY syncmaster 940n monitor repair

In general, this model is distinguished by ease of disassembly, as well as the free access of all the parts necessary for replacement, given that there is no external damage and only internal faults remain, so it is worth trying to carry out the repair yourself.

Before proceeding with the disassembly of the monitor, it is important that after disconnecting from the mains, some time has passed, preferably several hours, and in the meantime, prepare a Phillips screwdriver and prepare enough space for work, for example, a table and cover with a soft cloth.

For disassembly, the monitor is put down with the screen and, in turn, the fixing screws of the legs are unscrewed with a screwdriver, these are three pieces, and the cover is on four screws. There is no need to touch the rubber plugs.

Next, you need to be extremely careful to detach the back panel. Plastic is very fragile and can crack, so that this does not happen, it is worth using a thin and sharp object in the work. A scalpel is fine for this role. By disengaging each of the latches in turn, the lid will gradually open. It is important not to rush and work carefully so that you do not have to fix cracks.

After removing the cover, it is necessary to remove the second protective part of all internal electronics - the chrome plug. There is no particular difficulty here and it will be quite enough to slightly shift it to the side.

The next step is to disconnect all cables and a ribbon cable with side locks. These elements will only get in the way, and then the lid opens easily.

Now, in order to get to the monitor board, it remains to remove the plate and its three fastening bolts. Unscrew the bolts and remove the plate. All the electronic "stuffing" of the monitor is before your eyes and you can find the cause of the malfunction.

In this case, the cause of the breakdown of the Samsung SyncMaster 940N monitor was swollen capacitors, which can be seen with the naked eye, they need to be replaced, which can be ensured with soldering tools and proper skill, and the monitor will be ready for use, all that remains is to carefully assemble it without damaging the cable. If you are not sure of your abilities or it is not possible to perform a replacement, contact the repair specialists for help.

A Samsung 940N LCD monitor has been repaired with a declared malfunction - the image disappears a couple of seconds after turning on.

We try to turn it on - indeed, after turning it on, the image appears for a few seconds, then the screen goes out, that is, there is no image backlight, the image itself is present. We will disassemble.

We snap off all the latches along the monitor body with a pick and remove the back cover. We inspect the inverter board for swollen capacitors - there are no swollen capacitors. We try to throw in external lamps (we change all four).

The lamps are on and not extinguished. Everything is clear - the matter is in the lamps (that the matter in the lamps was clear a little earlier, when the image, which appeared for a few seconds, was dominated by red light, since the lamps are used in two colors - blue and red, it was immediately clear that it was burning weakly (or not lit at all) blue lamp). We will change the lamps.

The matrix name of this monitor is HSD190ME13.

We remove the piece of iron with the power supply-inverter board and with the interface board - the scaler board.

We unscrew the 3 screws from the top and carefully bend the matrix board towards the side. We snap off all the latches along the matrix body and take out the matrix itself from the iron frame.

Changing the lamp assemblies. The lamps in this monitor are installed CCFL 39cm * 9mm. Putting everything together in reverse order. We include.

We see a colorful splash screen with information that it is necessary to connect the signal cable to the computer. We connect - a beautiful image in which there is no longer a predominance of red. We put on a four-hour run with periodic off-on. Everything is working.

All photos are taken with Samsung GT-C3222 phone.

Samsung 940n monitor disassembly

Here is a step-by-step instruction on how to disassemble a samsung 940n monitor, a fairly popular model of LCD monitors, especially in the corporate segment. These monitors come to our service center with a "chronic" problem of this series - swollen capacitors (the power indicator blinks, but the signal is not displayed). Considering the ease of disassembly and the availability of the necessary spare parts, you can repair the Samsung 940n monitor without involving specialists from the service center. By the way, other monitors of this series (540n, 740n) are disassembled in the same way.

Attention. This instruction is not the ultimate truth. The author of the article does not bear absolutely any responsibility for the integrity of your technique. Start repairing only if you are confident in your abilities and have the appropriate education! And remember that you can always contact Triaservice specialists. We carry out high-quality repair of monitors samsung, lg, philips, asus, dell in Kharkov and the Kharkov region.

Samsung 940n monitor disassembly steps:

Unplug the monitor and place it face down.

Using a Phillips screwdriver, detach the leg, which is secured with three screws (you do not need to touch the rubber plugs). Attention.
It is necessary to detach the back panel very carefully, as the fasteners can crack (which, in principle, is not so scary). To open the 940n's lid, we need a scalpel or any other thin, sharp object.

Using a scalpel, we gradually open the lid, detaching the latches. Plastic may crack.

After removing the cover, go to the chrome plug. It is enough just to move it.

Then it is necessary to disconnect all interfering cables (including the cable, on the sides of which there are latches) 7. After that, the cover easily tilts

Access to the inverter board is blocked by a plate, which is fastened with three screws. We delete them.

We carefully inspect the capacitors for swelling. It is also worth checking the fuse.

Using soldering accessories, we replace them (2 * 1000mF 25V, 2 * 1000mF 16V, 1 * 470mF 25V, 1 * 47mF 50V).

We assemble the monitor in the reverse order, following this instruction. Pay particular attention to the train, as it can jam and interfere with closure.

We get a ready-to-use monitor.

If your samsung 940n does not work, it most likely needs to be sent to a service center or to the trash heap. Triaservice repairs lcd monitors samsung, lg, philips, asus and dell in Kharkov. We solve problems of any complexity, including replacing matrices. By contacting us you will save money, time and nerve cells. To contact the manager, go to the contacts section.

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Samsung 940N was brought with a standard diagnosis - extinguished, dark screen... There are three inflated containers in the power supply 1000 microfarads x 25 volts - c301, c111, c112... After replacement, nothing changes.

The inverter is assembled on a PWM controller BIT3195G and two assemblies of field-effect transistors.
We measure two field assemblies AP4502 on the back of the board. They are penetrated quite rarely, but it happens.
They represent an assembly of two opposite-sex field workers and are replaced by a more common assembly from the IRF series. I usually put IRF 7389 or IRF 7319... In this case, I blew my native 4502 from a similar monitor with a broken matrix.

Sometimes it is limited to replacing the fuse in the inverter power circuit. In this case, it is F301.
It will not hurt to replace the capacitor in the primary circuit of the power supply unit 47 microfarads x 50 volts c107 and in the secondary circuit 10 microfarads x 50 volts C123.Also, just in case, I change 33 microfarads x 25 volts in the area of the c345 inverter.

It rarely happens that inverter transformers fail. In this case, they survived.

SAMSUNG 940N (R). Do-it-yourself inverter repair when the required spare part is not available.

When the hand is full, there are no problems, now at least trances have appeared on sale, but to be honest, there have not been any refunds yet after reinstalling the inverters, the method is pretty quick and affordable for money.

Thank you, useful information! =) P.S. Author, learn the language!

@ phantomm134 repair (replacement of trance) or something else in the power circuit in an old monitor - no more than 4000 rubles. new monitor with NORMAL PICTURE QUALITY - 10-16t.r. there is a difference?

@ phantomm134 "with LED backlight." brrr. cheap and with LED light. this is a gvn and not a monitor.

Firstly: it is almost impossible to determine a short-circuited turn (turns) by a continuity for resistance, because their resistance is too small for an intuitive assessment, this can be done only by checking whether the inductance of the transformer winding changes if one of the windings is short-circuited. Secondly: the ballast for the lamp is a resonant system, the elements of the cut (including the inductance of the secondary winding) are calculated based on the capacity of the lamp, therefore not every tr-r may be suitable for a specific model 🙂

I had a problem this was the smell of burning, as if something burned out and the lower part of the monitor darkened and the upper light did not change. Monique Samsung sins master 2243 I would like to know the main REASON FOR THE BREAKAGE and the approximate COST of the repair they took me 2000 thousand rubles at the price of Monica at 5500 rubles

Hurray, you can continue to stare at the zombies and jerk off to this collective farm!

News and reviews of modern gadgets

The most common malfunction of monitors is the lack of backlighting. How to repair a Samsung SyncMaster 740 N LCD monitor with your own hands

Let's see how today disassemble and repair LCD monitor Samsung SyncMaster 740 N... A common symptom of a malfunction of this monitor's power supply is that the image blinks, the monitor cannot be turned on, the monitor turns itself off or turns on after a while. Also common lack of backlight on the monitor - this is when the image is visible only if you shine a lamp or flashlight on the matrix. More rare power supply problems are horizontal stripes in the image, noise, floating or bouncing images.

In general, to get to the power board, you need remove the back cover and monitor standso as not to get in the way. Next, you need to remove the front frame of the case, which is fastened with latches. The approximate location of the frame latches is shown in the photo.

Now you need to be careful disconnect the connectorthat goes to the buttons at the bottom of the monitor frame. Then pull out the matrix, disconnect the matrix cable and connectors of the backlight lamps.

We repair monitor samsung SyncMaster 940N.first experience in disassembly and diagnostics. **************************************

The back cover of the monitor is held by latches located around the perimeter of the monitor case. To open the latches, insert a strong thin object, such as an unnecessary plastic card or a metal ruler, into the gap between the screen frame and the back cover, and then sequentially and slowly unscrew all the latches holding the cover. Under the back cover, such a spectacle appears before us. In the next photo, the cover that covers the power connectors of the backlight lamps is also removed.

It should be noted that the metal casing visible in the photo above, to which most of the structural elements are attached, is fixed in the desired position with the help of the back cover and is not fixed to anything else. Before further disassembling the monitor, carefully document the wiring of all internal connectors. True, a real chance to confuse the connectors exists only for the power connectors for the backlight lamps.

Just in case, we fix the position of the remaining connectors.

Now, from the actual screen, you can remove the casing with the printed circuit boards fixed in it.

Then we remove the power supply board.

As expected, three failed electrolytic capacitors are visible on the board.

Finally, we disconnect the power supply board and remove the protective film that covers the board from the side of the printed conductors, this film is held on 3 plastic clips.

In addition to the obviously failed capacitors, a number of sources reviewed recommend replacing the C107 capacitor for preventive purposes.

This radio part has been replaced with a 47 μF x 250 V capacitor.

Just as the reviewed sources indicated, the fuse F301 breaks down along with the capacitors. In the photo, this is a green radio component, which is visible next to the swollen electrolytic capacitors.

We remove suspicious and clearly damaged radio components from the board. The main culprits are that the author of these lines was left without a computer on May 9, 2017.

In place of the failed radio components, we install similar capacitors.Instead of a 3 A fuse, a 3.15 A fuse with solder leads is installed.

After assembly, the monitor's performance was fully restored, after three weeks of intensive use, no deviations were noticed in the work. The author of the material is Denev.

Sometimes it is limited to replacing the fuse in the inverter power circuit. In this case, it is F301.
It will not hurt to replace the capacitor in the primary circuit of the power supply unit 47 microfarads x 50 volts c107 and in the secondary circuit 10 microfarads x 50 volts C123. Also, just in case, I change 33 microfarads x 25 volts in the area of the c345 inverter.

It rarely happens that inverter transformers fail. In this case, they survived.

I got the Samsung 940N monitor on the occasion. When turned on, an image appeared for a second, then the screen went out. During verification, a faulty backlight transformer was found (breakage of one secondary winding). There was no new transformer, and its replacement in workshops was slightly less than the cost of the monitor. It was decided to try to restore it at home.
The transformer was removed from the monitor board and inspected. Its design could not be disassembled. Since the converter for the backlight lamps was single-ended (there is most likely a gap in the core of the transformer), it was decided to carefully break it in order to try to restore it in the future (gaps during gluing should not greatly impair its operation).

With a screwdriver, its side jumpers were carefully broken off from the W-shaped core. Then, to free access to the winding, the plastic frame of the transformer.
The old winding was cut off and a new one was wound in its place, 8 sections of 80-100 turns in one section with a thin wire (it was 0.1), preferably even thinner is needed.

After winding the winding, the transformer core was glued with super glue. The photo shows the glued seam. The frame of the transformer was also glued together. It turned out without the upper protective part (the pieces were too small).

Below in the figure is a view of the transformer from the reverse side, a new winding on the left side, the terminals have not been soldered yet. After soldering the leads and dialing the transformer, the resistance of the new winding turned out to be much lower than the remaining one. Well, this is understandable, the new winding was wound with a wire thicker than the original one.

Next, the transformer was installed in the monitor power supply board (new winding on the underside of the board). The monitor was assembled and performance tested.
After turning on the monitor, all the backlight lamps lit up, the power supply did not go into protection. Test run of the monitor showed quite satisfactory operation of the repaired transformer.

It is also possible to restore the performance of the monitor without rewinding the transformer - by transferring the monitor to work only from 2 backlight lamps (one on top and one on the bottom), which can be powered from the remaining working secondary winding of the high-voltage transformer. To do this, it will be necessary to remove the SMD diode "CA2": D10 or D11 from the monitor's power supply board (depending on which transformer winding is faulty) and rearrange the backlight lamp connectors accordingly. The faulty winding will need to be mechanically, carefully removed (cut with a knife). After that, accordingly, the brightness of the monitor will decrease slightly, but the monitor will remain quite working.

I also changed the paleviks, and everything worked, thanks for the hint)))) One was broken)))

Hi, tell me please, there is a Samsung 943N monitor, I opened and changed the swollen 10v * 330mkf capacitor along the 5.1 volt line, then turned on Monique and lit up for a couple of seconds, the rest of all the capacitors are good, all the power on the terminals going to the lane corresponds, started A power supply unit without a lane by giving a signal to ON / OFF, also started up for a couple of seconds, the CCFL transformer is visually in good condition of the burners is not visible, the resistance of the secondary windings is 1st1052th, 2nd 1057th is this normal ?? What should I check in my case?

Alexei! you're a big lad! everything you have is just super! Please explain what the controller is behind the PWM and how it is powered. I have a Samsung 740n

Aerobatics! Bravo! It's nice to look at the work of a true master of his craft.

It is told and shown sensibly, with an arrangement. Well done! Thank you. As I attended the lesson. So beginners can learn without visiting the institute.)

Weird. My 940N has a completely different circuit, completely different from this one. This is my 740N

The soldered field should ring between 1 and 5, and between 1 and 6 legs.

Hello, I have the same monitor as yours. The Q201 of my board was burnt. PLease give me code of Q201, i want to replace this IC but i dont know the code. Please help, thank you.

The reason for the breakdown is not clear, how long will these assemblies last?

Well, I have almost the same monik, and this power board is an exact copy, I also made it, the textolite also swelled in one place.

knowingly working lamps when connected to an inverter
paws swear and go out
pwi2004sp board
what could be the problem?

measured the resistance resistance on the secondary windings, shows 1.14 kOhm on the wallpaper

soldered with an iron, it's not news that 90% of them work with hands

Please tell me which oscilloscope you are using. What is the minimum frequency to take an oscilloscope to repair monitor power supplies?

Prompt, there is a 13 Volt pin on the output connector. What is the power on this channel? The board says 0.0A. There is a desire to power a 12 volt scaler from it. Will it pull, is there about 1.2-2A?