Monitor Samsung 920n No Backlight

Repair monitor SAMSUNG SyncMaster 940N. No backlight. —————————————————————————————————————————————————–

151 Replies to “Repair SAMSUNG SyncMaster 940N Monitor. No backlight. ”

uh what a shaitan machine

Question: What approximately frequency are pulses applied to the gates of field-effect transistors?

Depends on the frequency of the PWM controller.

Dmitry Paderov 40-60khz

D’yakan FROST, how did you seriously narrow the frequency limits of PWM controllers. But what about converters operating at frequencies even higher than MHz?

Well, they are only found in the uterus. lowering. In a monk, honestly, I have not met such. There, usually, everything is according to the standard, in something similar to tl494.

Good day!! A question of the following order: there is a laptop HP CQ61 motherboard DA00P8MBD0 starts normally, but there is no, there is no screen backlight, C209, C188 and a couple more are heated from the back, I can not determine the designation. What can be and in which direction to dig? Thanks in advance for your reply. Sincerely your subscriber V.I.

Valery Ivanovich check with a tester the capacitors that are warming for the short circuit

Typical malfunction of this monitor model. Also recently changed both assemblies. They burn out apparently from overheating. The board itself serves as a radiator. By the way, from the factory under these assemblies glue. Apparently a type of heat sink to the board is made.

Pay Pts conducts heat badly. Glue is needed for fixing, so that the microcircuit does not fall off until it is soldered. in production.

vanobogom Well, for the first time they die from increased ripples, when the litas at 13v dry. Not always true, but cases are not rare. And here from what repeatedly. that still a riddle.

Alexey, it would be great if, at the moment when you show the oscilloscope, you would still show the place where you put the probe. Thanks!

This is still normal soldering, in a hurry to see the stern monitor after all. It happens worse, the textolite on these boards is lousy, and with small exaggerations the temperature does not withstand and quickly swells and blackens, and here, judging by the spot, they heated with a hairdryer when dismantling field workers. Still, they die due to overheating (personal observations), their exertion is easily recognized by a fused or burned plastic screen. In the following revisions, this was provided for, and places were developed for the radiator, the fastenings of which, on the reverse side, directly fit and capture the conclusions of the field workers.

Sorry, but what could be of symptomatology if the tablet starts blinking, that is, it restarts cyclically. After it completely ceases to show signs of life, both no reaction to the key, or when power is supplied from the charger?

Broken or falling off emmc, for example.

Lothantriary Today he began to show signs of life, when the mains power is connected. it flickers. This can not be a consequence of a complete discharge of the battery?

I propose to disassemble and audit.

Lothantriary Thank you for responding to a call for help. Performance has been successfully restored. It turns out the culprit of this dull triumph was charging. I bought a new one and wooing the tablet started without whims. Thank you again very much.

Like always! thanks for yours!

Alexei, I’m already watching your channel instead of TV shows. Much more fun, and even useful. I have a dream for you to open the rubric on learning from the basics. It’s very clear for you to explain clearly and readily. I am waiting for each series, as once Dr. House was waiting for the Episodes # 128578;

Well done, everything is intelligible and clear! And about the previous service, of course I’m in shock especially as the author says the service is supposedly serious. Like it! We are waiting for the next.!

Of the many channels that I have subscribed to on the subject of “diagnostics and repair”, Alexey’s channel for submitting material is by far the best.
It is especially nice that there is no narrowly focused topic. everything that is powered by electricity is being repaired # 128578;

Today they brought a monitor from the service. half the bolts are gone. I did not understand the reason for the non-inclusion (the power indicator did not light), but after complete disassembly and connection on the measurement table, the indicator turned on. Does not respond to strikes (no nepropaev). Collected. everything works. Oxides in wire contacts?

Everything is bought on Ali

Alexander Pichushkin and Denis One- I totally agree with you! Well done author, and keep it up.

That’s the whole problem that the device does not seem to be short on capacitors

recently repaired a laptop after a service center, they refused to repair there, said it was not repairable, and named the reasons that were not confirmed! trust after that prof. service centers

Thank you for your work. Real technical porn. # 128578;

Thanks Alexey! Very detailed and understandable, good luck with everything!

There is an EO-6M oscilloscope, there are no “cells” on the screen, can they be restored? Thanks in advance.

Dear, help with the same Monique. After turning on, after 3 seconds it goes to short circuit. And it turns off. Condors were swollen the local master did, up to a normal ss 200 km.

In Copper, what does it mean in KZ. voltage disappear chtoli or does the backlight still turn off?

I heard a high-frequency squeak and everything turns off.

In Copper, measure the voltage at the connector before and after switching on to start

Such a monitor costs 1.5-2t.r., fuck such a shit to repair?

It’s not about the money; the process itself is interesting!

qefyr 1.5-2t.r. This is used, which in 99% within a year or two will also fly from a similar sore. it’s senile. So does it make sense to change the flea?

Of course, I myself am still that master felt-tip pen, and I’m not soldering a fountain, but when I saw the transistors soldered by miracle masters I simply said. FUCK! No more words!

Just awesome. In detail, intelligibly, without unnecessary chatter.

The question has not been resolved, what was the cause of the breakdown? Why did the field workers die? The riddle however.

Sorry for the offtopic.))
Help out with a hint.))
In the Acer AL1916W As monitor, you need to replace two AOP605 microcircuits in the inventory. Mukrukhs with different serials (?). I found a replacement for one field assembly (BD6P27). IRF7389, albeit in a smd case, but I can get out But about the second BD6P16. I can’t find anything anywhere (I can’t even find about its insides, not to mention analogs).
But if this is one mikruha with a different series, can I use the same analogue as the first?
Tell me, please, it’s a pity to throw out, it is not profitable to carry out repairs, but I often use two, or even three monitors.))

Evgeny Kozlov that is, do you have 2 chips with the same names and different serial numbers (batch numbers)?

HamRadio Tag, absolutely right! )))

Evgeny Kozlov do not pay attention to the serial. this is only an encryption of the release date and other official unnecessary information

God, what a quality of the SC, I even solder a dog better,))
Now it’s clear why it is unsuitable for repair, hehe

Help please! My Samsung monitor went out of order. The image is bright, it slows down. Once it took about 5 seconds for the normal image to turn back to lit up, there were still streaks Thank you.

And you can tell by the same monitor. Does not respond to the power button, the power indicator does not light up. How can I start the test? I have only a workshop and a soldering iron.

Something in the contact is silence, do not consider it work. I measured the voltage at 605 after the diode bridge there is 350 volts.

did you create a topic in a group? I did not see messages

Is there a circuit? create a topic in a group and send a photo where measured

No, I did not create a topic, I wrote in the comments about the monitor. Yes, there is a scheme.

And for what reason that watering burned, please tell me.

The people are the best specialist who I have ever come across. He is the guru of his own business. He helped repair the monitor at a distance by asking one question and getting only one answer. If you decide to repair your electronics in Taganrog, this master is the best. Right, if necessary, I’m ready to give “Tooth” in confirmation of what was said. Alexei Respect.

Tell me please. My monitor turns on, and after 3 seconds goes into standby mode. After turning the monitor on and off, the same situation occurs. What could be the problem?

Denis Valenko checked the capacitors for a start?

Even replaced with new ones. Anyway. Of course, the high-voltage did not change. But in appearance it is whole

Denis Valenko then disassemble the matrix and see if the wires on one of the lamps are burned out or the lamps at the ends are blackened

The monitor turns on and the image is normal (not dark). Thank you, I will watch now

In the 920 NW monitor, after replacing the swollen capacitor 1000 by 25 (I respected the polarity), when I tried to connect the monitor to the power, the thermistor or varistor burned out (unsure, it burst and the inscription floor is invisible, but I suspect it is SCK-054, disk, green right next to the connector for nutrition) tell me what it may be related to?

Zhenya Mokha as an option kz in the hot part of the power supply. also check the backlight inverter transistors

HamRadio Tag, it’s interesting that before replacing the capacitor, the monitor turned on for 3 seconds even if the thermistor was intact, I can’t understand how the new capacitor could affect the thermistor

Monitor Samsung 920n No Backlight


Gentlemen, there is a “younger brother”. 740N, which has become unstable to turn on. i.e. it turns on, the image appears, the picture is there, but after a while 1-2-3-5 seconds off, and so on for several minutes. Recently, it can last up to 10 minutes or more.
There are suspicions of capacitors in the power supply circuit (825mF25V). Tell me, should I replace it immediately, or can I still wait? If these Conders are completely bent, will they not bring something else with them?

sweetbox0778 c
immediately better to repair

HamRadio Tag Thank you.

HamRadio Tag I made my monitor. When I opened it, it turned out that the modification of the power supply board and the inverter was slightly different, and the rating of the “pregnant” capacitors was different. 470 MkF25V. all three were swollen, the capacitance dropped to 16-47 MkF, the internal resistance began to be 8-15 Ohm. Replaced by 100025V Jamicon WL In addition, we had to replace the nearby capacitor 100010V, replaced by the same one at par, Jamicon WL. The monitor seems to be working, but now for some reason it seems to me that the brightness doesn’t really want to be adjusted. even with the brightness turned off “to zero”, the picture seems very bright. Maybe I quibble of course.

Hello, I am a pensioner and a little bit involved in the repair of equipment. And I’m learning from you. And once you took the manual on the schemes in the Service Manual. Please tell me where and how to get the schemes for repairing TV sets of the 1990s. LG, Samsung, Goldstar, etc. THANKS. BORIS

tell me the monitor does not turn on. and when I pull out the cable the screen just burns and when I stick the cable back. everything works

Gandons are stupid, he soldered everything correctly. Heat removal from drains (drains) is so much better


All actions are tactful, consistent and clear! 5

AP4525GEH cannot be replaced by IRF7389 ??

Gavr Smit if the drains on the board are connected then you can

And the fact that there according to the date of the shield is something like a Zener diode between the base and the source, something like a Zener diode is not that terrible?

Tell me about this problem: the monitor turns off a few seconds after turning on from the button. Could there be a problem in the backlight? And how can they be checked without having to replace them?

Re-burnout of assemblies after replacement. Tell the lover where to dig?

Igor Niki ripple inverter, inverter

Hamradio tag
electrolytes at 25v were replaced, the rest seemingly normal. The second breakdown passed within half an hour, until he left for inspection and was distracted. High-voltage transformers. on the secondary order of 1280

Igor Niki
the assemblies are heated, the protective plate is already burnt out. over, before assembly, on a test run, after several minutes of assembly, they were not hot

HA HA HA Dude. what are you treating us with that you repair yourself? Your Fixik runs on a multimeter )))) Who doesn’t believe, look at 17 minutes 10 seconds That’s who fixes everything for him.

Andron! just in the 17th minute, he found everything and ran for a new board

Hello, uv. Alexei!
I had to visit Taganrog, at the Priboy factory, about 45 years ago
Recently I found an LCD monitor “in the trash”, I decided to repair it.
I read a couple of service manuals on the Internet, went to a few
forums, watched a fews. The bests are yours, how
the most systematic and clearly stated, and here are a few comments:
1. I do not advise famously brushing off dust with a brush because of the possible
damage to digital circuits by static electricity, and
IMS failures can occur over time. Dust is better to blow
vacuum cleaner or hairdryer with cold air. Then with a wet brush
wipe off any remaining dust. Do not neglect the grounding bracelet,
cotton clothes and a low-voltage soldering iron.
2. You use RED-COPPER to “suck” the molten solder
braid. In the 80s at the Kaliningrad Institute for Advanced Studies
marine specialists lecturer in microelectronics, candidate of VM
Rosen B. S. considered this method the best rationalization proposal.
in the fleet, effectively removing completely solder even with double-sided
installation during the extraction of the most complex ICs. Braid used with cores
cable type KMPVE, wetted in a solution of rosin in alcohol. It’s better
often woven braid of the thinnest wires.
3. When fuse F301 is burned, it can be wound and
solder the 3 amp fuse from the glass fuse.
4. The operability of the inverter at the output is easily checked by bringing any
neon light bulb to high voltage capacitors or windings
transformers, even with disconnected or faulty lamps
backlight. while neonka briefly lights up when turned on
button circuits.
I wish you success in your work!
On your, the monitor matrix is ​​very dirty.
It is worth pointing out that its cleaning is a special thing, on the Internet is enough
information on this subject.

transistors of the backlight injector burned out, tell me the reason please.

Valentin Vitalyevich Illumination lamps fail over time, they are not eternal. Dying lamps require more and more current to work, and at some point a thermal breakdown of the transistor occurs, or simply a breakdown of the secondary winding of the transformer occurs, and also only one field pole from the assembly most often leaves the power source.

I changed these assemblies twice, they constantly crashed after 2-3 monitor turns on, they were very hot (but I could hold my finger) until I replaced all the conductors in the inverter power circuit, after which when I turned on the assemblies they stopped warming altogether, since then, about 5-8 xs years of normal flight, did not touch the lamp.

Hello. My Samsung 225 BW monitor does not turn on. And does not respond to the inclusion button i.e. The button lights up, I press it does not go out. Tell me what is the problem? thanks in advance

Uncle you are literate! Really cool! But how do you know all this?

Hmm, with the depreciation of the ruble, rewinding such a yg is again in trend. I forgot to check the lamp currents. And then they will bring it again in 2-3 weeks.

It’s nice to see and listen to a professional. Thanks a lot to the author of the, I hope one of the philanthropists watches this and gives a good digital oscilloscope.

Please tell me, on the monica syncmaster 740N, the green vertical strip is one pixel wide. What is the reason? When the box itself was disassembled, Monica pressed along the edges, sometimes the strip disappeared, but in the end she remained so

How do you clean flux boards?

Andrey Agapiy
At the factory, they are washed with an alcohol-gasoline mixture or simply with alcohol.

thanks a lot. very intelligible

Hello! The LCD monitor has 4 lamps, 2 circuits in which 2 lamps are connected in series. What capacitor or resistor can replace 1 burned out lamp? That the monitor worked on 3 lamps. Help? Thank you in advance.

Thank you, the soldering of three capacitors and a fuse helped (instead of 3A I put 5A. there was no other at hand), capacitors at 1000 microfarads 25 V, although 85 ° C, but isolated from the radiator with a cloth.

Thank you for the!
I’m in the training stage, do not judge strictly))
Tell me please !
The diagnosis. when the monitor is connected without a cable to the network. works, when the cable is connected, an image appears and disappears after a second!
During disassembly, one swollen capacitor was found, it was replaced with a new one of the same values ​​- but it is rather smaller, maybe it’s a fake !?
After turning on, everything repeats!
Monitor SAMSUNG SyncMaster T220P
Can change all capacitors. although they look healthy in appearance !?

Hello, help on the monitor inverter board in the circuit of the high-voltage transformer there are smd resistors, they were warming up and burned out, I would like to know why they are needed there at all

hi. help if you can, such a problem the screen on the TV went out, but if you look closely, the picture is visible. as if the brightness and contrast are at zero. the remote control responds. thanks in advance.

rum mamedov Either the lamp burned out, or the inverter backlight.

I reviewed a lot of Samsung monitor repairs. Everywhere they talk about Conders and inverters. But I did not find a that talks about replacing the backlight itself. I had one Samsung 920N monitor. He just turns on the power button, it lights up, the backlight turns on and goes out. In it, I changed only swollen capacitors and it worked. Another Samsung 740n monitor, when turned on, the backlight also started and went out later, but the monitor could start from the 10th or 3rd time. If we get lucky. As a result, it stopped running at all. At autopsy, I found swollen capacitors, replaced, the effect is zero. I rummaged through the entire board, made voltage measurements, everything corresponded to the norms. But still, when turned on, Monique went to the defense. The indicator lamp is on and there is no backlight. If you look closely, you could see the image without backlighting. So the monitor itself is working. It remains only the last, to disassemble the matrix of the monitor and check the backlight. After disassembling the matrix, I found the cause of my problems. One of the backlight lamps burst. There are 4 of them. If one of the 4 lamps fails, the protection is triggered. And the inverter cannot start the backlight. I bought 4 lamps in the store. In Kazakhstan, they cost 500 tenge apiece, which is 100 rubles Russian. It was not assembled, I had to take it in bulk. But to change them you need a lot of patience. This is a complete hemorrhoid. Good when they are sold complete with chips together. That was my problem. Changed the lamp and it worked.

Today the same repaired, changed these three Conder and fuse, and voila. everything works)))

By the way, how many monitors were picking, textolite in the models of recent years, Acer, LV, Vyusonik, of disgusting quality, it is worth heating more than 250 grams of C, and for 5 seconds it starts to swell. It seems that they use getinax.

they also have such shnyaga in the center of getinaks on the outer layers fiberglass layers usually such in BP. textolite looks like.

Ser beer
Come on! I’m in SHOCK! In horror, I imagine those process in which such boards are produced)) Here is a fucking Chinese genius)))

Thank you for the and tip! I’m going to open the SC! If the equipment is with swollen capacitors, then I change it, and if not, then it cannot be repaired.

Hello master, tell me please, I can’t find the “” Thermistor SCK 084 ″ “in the city. Is it possible to put another part instead, if it is possible which one.

As for soldering in the SC, this is a question for the owner of the SC !? Well, they don’t want to pay for the work of the masters at the proper level! And as for the co-workers, so many co-workers work for themselves, and they do it more professionally than some “masters” It’s easier for him to recruit students and “students” and not pay extra to them. Rather than take one master, who alone will have to pay two or more times more than all these amateurs. (