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.

Image - DIY syncmaster 940n monitor repair

Image - DIY syncmaster 940n monitor repair

Image - DIY syncmaster 940n monitor repair

Image - DIY syncmaster 940n monitor repair

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).

Image - DIY syncmaster 940n monitor repair

Image - DIY syncmaster 940n monitor repair

Image - DIY syncmaster 940n monitor repair

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