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12.10.10 | How to fix your LCD monitor – changing capacitors
Filed under: Computer — Tags: , , , — Dr. Ivan @ 21:46 — Comments (81)

Have your LCD monitor died recently and you are planning on buying a new one? If so, do you want to know how you can save yourself several hundred bucks and repair the old one instead – with replacement parts barely worth a 1 or 2 dollars? Find out how in the guide below.

Background

First off – a quick story about how it all began.

My monitor had been behaving strangely for a couple of weeks – from time to time pixels would begin to flicker in lines or rectangles along certain parts of the screen. Some time later, it began to turn itself repeatedly on and off when it was woken up from power-saving sleep. Finally it would longer turn on at all. I was somewhat disappointed since it only had been two years since I bought it. Don’t misunderstand me here – it was by no means an expensive LCD. This was your middle-range consumer TN-based panel with a price point around 200$. For this price you probably shouldn’t expect too much quality, however it’s of course a pity to let your hard-earned money go to waste – not to mention putting additional strain on the environment.

In the following concise guide I will walk you through how you can repair probably the most common hardware problem with LCD monitors – power supply’s malfunctioning capacitors . The best part of it is that the cost of replacement parts is almost negligible.

So, before we get started PLEASE NOTE: You *MUST* take elementary precautions when dealing with consumer electronics. Always unplug the equipment before disassembly, ground yourself and never attempt to short-circuit any device. Never heat up, over-voltage or open capacitors.

The Problem At Hand

Modern monitors are advanced pieces of electronic equipment. Many problems may arise during a life time of such device, however by far the most common problems are capacitor-related. Capacitors (or caps for short) are small usually cylinder shaped circuitry parts concerned with storing a limited amount of energy. Their physical properties allow them to be used for smoothing out power supply output, and as such are essential for almost any electronic device nowadays. Unfortunately – being so crucial they are also the parts that are most prone to failure. This can be due to poor production quality of the capacitors themselves, or a flawed monitor design not dissipating enough heat. Japanese capacitors are rumored to be the best, however not even they are completely fail proof.

First off, you must find out if your problem is capacitor-related. This will involve you disassembling your monitor (be sure to unplug it from both power and your computer before you start). It is very handy to take pictures after removing each large part – that way you will be able to easily re-assemble the monitor when you are done by just looking at the pictures in reversed order. Below you can see a picture showing me disassembling my monitor, a Samsung SyncMaster 206BW:

 

disassembly

 

The part you should be specifically looking for is the power supply unit. It is often on a separate board and will have the power cord connector (where you plug in your power cable) sitting on top. Mine looks like this:

 

board_front

 

This board will contain a number of caps in various locations. Inspect each one carefully, especially the top aluminum part marked with a cross (see pictures below). If busted capacitors are indeed the root of the problem, you will usually (but unfortunately not always) see that their upper part of is bulging upwards and may have traces of dried liquid on top. Take utmost caution handling leaking caps, use gloves and wash your hands with large amount of water if you come in contact with the liquid. Here are a couple of pictures showing the blown caps in my monitor:

blown_caps_1
click to enlarge

blown_caps_2
click to enlarge

 

Replacement Parts And Other Equipment

After having found the defunct caps, look at the text on their side. It should state something like “1000 uF 25 V” – take note of this. The first value is the capacitance and the second is maximum voltage the cap is designed for. In my case I had to replace two 1000 uF / 25V caps and a 470 uF / 25V cap. To get hold of spare parts, go to eBay. This is by far the cheapest alternative (unless you absolutely want to get top-of-the-range caps, which is case of self-repairing rather unnecessary). Search for the values you have just written down and order a batch of each cap type you require. This won’t cost you more than perhaps 5 bucks – and even less if you are lucky. Otherwise you can always pay your local electronic part store a visit – they might even sell single capacitors so that you avoid paying for a whole batch and just get what you specifically need.

 

new_and_old

 

Soldering equipment is of course also required. Here is a list of miscellaneous equipment I used along with a picture of the tools:

misc_tools
click to enlarge

  • Caps with correct capacitance and rated for appropriate voltage (as described above)
  • Soldering iron and solder.
  • Copper desoldering wire is preferred but not necessarily required.
  • Screwdriver (for disassembly)
  • Pliers
  • Wirecutter

 

Replacing The Caps

When you have gotten all your equipment ready and received the replacement caps, its time to get to work.

Again locate the busted caps. Note their polarity (it’s usually also printed on the board). Turn the board upside down, locate the two pins belonging to each cap. You can see that each pin is soldered to the board and has a small droplet of solder around it. Place your desoldering wire on top of each of these droplets in turn, and put your pre-heated soldering iron on top of the desoldering wire. Wait until the solder from the joint heats up and gets sucked into the copper wire.

board_back
click to enlarge

desoldering
click to enlarge

The cap pins will then become loose and the capacitor can be taken off the board. You will most probably need someone to assist you with this task by slightly pulling at the cap on the other side. You should use pliers for the latter since components might get really hot during this procedure. When all old capacitors are off, place the new ones in the remaining holes double-checking polarity and capacitance value of each cap. Solder them in place and cut off the excess length of the pins.

board_back_desoldered
click to enlarge

soldering
click to enlarge

wire_cut
click to enlarge

On a side notice, if you do not have desoldering wire, just cut the caps off the board with a wirecutter and then solder the new ones on the short stumps of wire the old caps left behind. This is not ideal, but might work for you nonetheless. Yet again – remember to check that the new caps are placed correctly in terms of polarity.

Voilà! Now just re-assemble you monitor and see if it works. Hopefully you are yet again a happy owner of a fully functional LCD panel – who both saved 200 odd dollars and learned something new:

 

working_2

 

Conclusion

If you have any thoughts to share about this article – or perhaps having trouble with this procedure – feel free to leave a comment!

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81 Comments »

  1. avatar

    Thanks for this. Was just about to pay for a new monitor and came across this site. Replaced 2 capacitors for £1.29 and it works perfectly :)

    Comment by Ste — 02/11/2010 @ 13:53

  2. avatar

    @Ste: I’m very glad it worked for you! :D

    Comment by Dr. Ivan — 02/11/2010 @ 14:25

  3. avatar

    Doc
    I have an Acer LCD and it is now quite blurry. Is this a capacitor problem as you have described?
    thanks,
    Dave

    Comment by Dave — 09/11/2010 @ 16:20

  4. avatar

    Hi, Dave!

    That really depends on what you mean by blurry. If you are talking about colors or the general image quality, faulty capacitors are probably not your problem.

    If this is an old well-used monitor, this can (at least theoretically) be just a sign of old age – especially if this occurred over time. If it was a more sudden change, it might be a software problem. Or, depending on how this blurriness manifests, the backlight is perhaps giving up (in which case you are better off buying a new monitor).

    You can of course still open up your LCD and take a look at the capacitors. That might not prove to be useful, but then you can just put it back together without any further tinkering – and you’ve lost nothing!

    Comment by Dr. Ivan — 09/11/2010 @ 17:45

  5. avatar

    Doc
    Wow – thanks very much for the qick response.
    Yes developed over time, words are blurry – especially as monitor warms up, heavily used monitor… I think it is time for a new one!
    Thanks again.
    Dave

    Comment by Dave — 10/11/2010 @ 13:16

  6. avatar

    My pleasure, Dave :)

    Comment by Dr. Ivan — 11/11/2010 @ 18:33

  7. avatar

    My LCD changes colors to reddish after running for hours. Tried changing cables and stuff but obviously the problem is not there since it only happens after few hours of running.

    Can this be a capacitor issue?

    Thanks

    Comment by Pacifier — 22/02/2011 @ 19:10

  8. avatar

    Hello there, Pacifier!

    I think your problem is most probably related to over-heating – at least that’s what it sounds like to me. To confirm this, when the problem occurs – turn off the screen, wait for 15 minutes than turn it on again. If the problem is (at least to some degree) alleviated, then heat is certainly the culprit.

    Unfortunately, in this case replacing the capacitors will not help. You may however try to make sure that your monitor is located at some distance from the wall and the ventilation grills on its back side are not covered to allow for maximum ventilation at all times. If all else fails you can try to actively cool off the monitor by placing a table fan (or something similar) and direct it at the back of your monitor. This is of course not very practical, but it might help…

    Good luck!

    Comment by Dr. Ivan — 24/02/2011 @ 23:29

  9. avatar

    Thanks Dr. Ivan. The color problem goes away only if I remove the power and keep it off for a day. I don’t think it can overheat for that long?

    Comment by Pacifier — 25/02/2011 @ 14:59

  10. avatar

    Hello again, Pacifier! Sorry for not coming back to you sooner.

    Yes, a monitor should be able to cool down way faster than one whole day. However – you never know, try to take the back cover off and see if perhaps ventilation holes are clogged up with dust.

    Otherwise I am slightly at a loss here – I am not entirely sure what the problem might be. Perhaps it *is* indeed faulty circuitry. In any case it won’t hurt to double check that the capacitors are OK.

    Comment by Dr. Ivan — 05/03/2011 @ 20:03

  11. avatar

    hi, doc
    i have replaced the broken capacitors, but my screen still doesn’t work it just shows nothing when i turn it on, do you have some advise on what it possible be??

    Comment by leon — 21/04/2011 @ 17:17

  12. avatar

    Hi, there, leon!

    Well, first of all: Does the small LED light up when you turn the monitor on? If not, chances are you might have placed some of the capacitors incorrectly. Double-check that all of your new caps have been placed according to specified polarity, voltage rating and capacitance. Also make sure that you have connected all the wires properly when re-assembling your monitor (f.ex. ribbon connections between the power unit and the decoder unit) – it’s very easy to miss!

    If you do not find any errors, but the monitor still fails to show any image – then the problem is most probably elsewhere. In this case, sadly, you might be out of luck. You could potentially try to locate a faulty component using a multimeter (assuming that that is the issue – although it’s not always that easy either). However, this can be a daunting process due to the circuitry complexity often encountered in today’s consumer electronics (and to be honest with you, I’ve never done this myself).

    To clarify even further: Unfortunately it is only this far one can get with DIY when it comes to LCDs these days. Electronics enthusiasts may be able to replace background lighting components, capacitors and perhaps amend some obvious physical damage, but that is pretty much it. For anything more advanced you will almost always have to seek out professional repair (which will most probably run you several hundred bucks – raising the inevitable question about whether it would have been cheaper to buy a new monitor all together).

    Comment by Dr. Ivan — 21/04/2011 @ 17:48

  13. avatar

    doc
    the green light goes on, when turned on!i took the power supply bord in to a computer store and they put in the new capacitors for me so i asume that it was done correctly.

    And i’am sure that i put it back together correctly. I just want to make sure i’ll check again if everything is ok on the power supply bord then i will not be able to fix it myself!!

    Where can i find out what the power outputs on the different pins must be to check if its right??

    Comment by leon — 21/04/2011 @ 18:43

  14. avatar

    OK, I see.

    As far as I understand what you are trying to do is to measure voltage on the power supply output pins, is that right? If I am not totally missing the point here, it implies having the power supply connected to the wall wart while testing. If so, I do have to warn you: this is *IMMENSELY* dangerous due to possibility of electric shock (especially when you suspect the power circuitry in question not to be functioning properly). I would strongly advice against any kind of testing on a plugged-in power board.

    Otherwise, it can be pretty difficult to figure out what voltages should be on what pins – manufacturers usually don’t disclose schematics for the equipment they produce. Your safest bet here would perhaps be to look on the board itself for indicators such as “+3.3V” and “+5V”.

    Comment by Dr. Ivan — 21/04/2011 @ 22:51

  15. avatar

    Hello. You seem like you know what you are talking about and you respond quickly so I am leaving my input on this site. I have been searching around for two days now. I found 3 bulging caps on the power board and replaced those. But, I am still having the same exact problem. Though, honestly I am just happy the monitor powered up after my fix lol.

    When you turn on the monitor it displays a default samsung logo. Its a Samsung 215tw. This logo will have multiple copies of itself. Like 4. And there will be different colored vertical lines. The lines seem to only appear when menu boxes appear. Whats happening is, you know when a tv logo will kinda teleport around the screen?, well the monitor isn’t refreshing fast enough and you end up seeing all instances of the logo at once. well not all.. about 5 at a time. When I connect a source to display picture the lines seem to go away but I still experience very slow refresh times, and the definition is blurry all around. I don’t mean like just text. The overall display just has this blurry feel. I would imagine its similar to being on drugs. No joke. This was my brother’s monitor and as far as I know this happened mostly all at once. Not a gradual thing.

    Do you think the screen is bad? Or possibly the Signal board? There are only two boards. The power and the signal/source boards. The signal board has the caps that kinda sit inside this little square platform. And I don’t know how to test nor replace them. Any ideas? Is this monitor just scrap? I would really like to beable to use it, but I don’t want to just throw money into it. Thanks.

    Comment by Tony — 01/12/2011 @ 08:27

  16. avatar

    Hi Tony!

    Yeah, I don’t think this has anything to do with the power board anymore ;) Sounds like a problem with a fried signal board, or some weird firmware glitch. It could possibly still be due to some blown components on the signal board which could potentially be replaced – but I highly doubt that it will be worth it. Those boards are a nightmare to error search!

    I think you should be considering a new monitor, it will most probably save you many sleepless nights, and perhaps even some money ^^

    Dr.

    Comment by Dr. Ivan — 03/12/2011 @ 12:51

  17. avatar

    Thanks I appreciate your time. =D And, I agree with you. I will use the working caps on that board for use in these two other monitors I picked up from my friend. ^_~

    Comment by Tony — 03/12/2011 @ 19:35

  18. avatar

    hi??

    Comment by cutty — 31/01/2012 @ 17:28

  19. avatar

    Hi, cutty!

    Comment by Dr. Ivan — 01/02/2012 @ 08:49

  20. avatar

    dear sir,i would like to know about my lcd problem.can u send me mail pls.my lcd have problem bcoz of 2 capacitore blowing up.i changed.and re fix my lcd.but still not working.blinking power light.no screen disply.pls help me to solve this problems.waiting for your great reply asap.thank u.with regards,sha. clock24@hotmail.com

    Comment by sha — 24/06/2012 @ 00:39

  21. avatar

    Hi sha! There are three options:

    1) may be there are more caps that need fixing
    2) or, you perhaps have switched the polarity of the caps by mistake
    3) or, simply, the problem does not lie with the caps at all

    In any case I will not be able to help, sorry – double check your setup! When it comes to (3) – monitor repair (besides changing caps) is rather complex, and in my opinion not worth it – neither in relation to money nor time spent.

    Dr.

    Comment by Dr. Ivan — 24/06/2012 @ 01:07

  22. avatar

    First thanks for the info that you share.

    It that knowledge I get my monitor working again.

    about the caps…. this caps have 2 legs… the short one is the negative (MINUS). it’s simple and I dont know more about the electronics.

    Best regards from Bucharest – ROMANIA

    Comment by adrian — 13/07/2012 @ 09:15

  23. avatar

    I’ve been having problems with one out of two identical monitors for years, a ViewSonic VP211b. Whenever starting up or waking up the computer it has been tricky to re-establish the connection. The computer never saw a problem, finding the monitor and sending a signal, as long as the DVI cable was connected. Yet the monitor pretended there was no input. After sending the computer to “detect displays” (Mac) and turning the monitor on at just the right moment it would finally work after many many attempts. Which was why I left the computer running at all times. Once the connection was established there were no problems, even with the monitor going into power save mode.

    This time however I can’t get the “detect displays” trick to work anymore. Also, the OSD message of “no input” is blinking irregularly all of a sudden (but not due to the monitor lamp as it seems).

    Question… Capacitor related? Graphics card is ruled out for sure btw. Thanks in advance.

    Comment by spin — 06/09/2012 @ 21:00

  24. avatar

    Hi spin!

    No that is probably not related to capacitors – with caps you will get artifacts and power problems. If you have tried to change the cable (and checked that all pins are intact etc), I unfortunately can’t help you. Not even sure if it is a hardware or software (firmware)-related problem. Sorry, mate! Hope you’ll be able to fix it though! (drop me a line if you do – would be great to learn;)

    dr.

    Comment by Dr. Ivan — 07/09/2012 @ 11:35

  25. avatar

    Before I could order the caps, a well-meaning member of my society gave our non-working monitor to his good friend who has business of fixing monitors.
    Two weeks later, when i called this professional TV/Monitor guy, he said the screen was bad.
    I asked him to return it to us. Two more weks have gone by…,no monitor .yet.
    How does the screen go bad?
    Thank you
    Joe

    Comment by Joe Bryer — 22/09/2012 @ 02:33

  26. avatar

    Hello Joe,

    I am very sorry to hear that! Perhaps he meant that the screen was beyond repair? Perhaps some other component was at fault, and not the caps? A screen has a number of components that are sensitive to f.ex. heat. If it overheats other circuitry might be fried – and that might not be as easy to repair.

    But that is really the only explanation I’ve got…

    Hope you get your monitor back eventually!
    Dr.

    Comment by Dr. Ivan — 22/09/2012 @ 05:17

  27. avatar

    Hi Joe,

    I have a problem whit samsung lcd monitor, is like your lcd, but my problem is: first time when i turn on the lcd blinks in every second for 30 minutes…after that is need to pres power button for 20-30 times to stay on [is same problem like your? and when lcd blinks make a little noise (little)]

    Thanks and sorry for my bad english, I’m begginer

    Comment by octa2k — 22/09/2012 @ 10:49

  28. avatar

    Dear Dr,

    My LCD monitor has experienced color changes and more liiumination on it. It has large white patch when power on and later disappers. Will this also be a problem of caps.

    Comment by Nir — 27/09/2012 @ 06:55

  29. avatar

    Hi Nir!

    Not quite sure what you mean by “more illumination”, but no – that does not sound capacitor-related. However, if there is some problems with light – perhaps the backlight is going bad? That is a rather frequent problem that occurs with age. Depending on your monitor, you can fix it yourself, although be advised that changing backlight can be *very* laborious in some cases!

    Dr.

    Comment by Dr. Ivan — 27/09/2012 @ 19:30

  30. avatar

    Saw many of the posts and was wondering if you had some ideas about my Dell Ultrasharp 2408WFP. Black is being displayed as very bright Green. Any ideas of what might be the issue? Thanks.

    Comment by Janet — 01/10/2012 @ 22:14

  31. avatar

    Hi Janet!

    Yeah, I’ve had that problem! It is either the cable or the connectors (in case it’s VGA), or its the logic board :) Try to buy a new cable, otherwise I don’t believe there is much you can do…

    Dr.

    Comment by Dr. Ivan — 01/10/2012 @ 22:50

  32. avatar

    my acer lcd moniter is on but after 10 minutes off many times i change the pc but the problem is happen how to solve this problem

    Comment by hadya — 03/10/2012 @ 09:31

  33. avatar

    please help every body about his problem

    Comment by hadya — 03/10/2012 @ 09:32

  34. avatar

    Hi hadya!

    OK, so it works for 10 minutes then turns off? It might be overheating or a problem with the power board. Be sure not to cover your monitor, so that the ventilation holes are not blocked. Personally I wouldn’t touch anything that has with power with a ten foot pole. It can be very *very* dangerous – you can easily electrocute yourself. So I would personally opt for a new monitor :)

    Dr.

    Comment by Dr. Ivan — 03/10/2012 @ 17:30

  35. avatar

    Doc,

    Well, I’m an IT Professional and I’ve done the cable route…. was using DVI-D, changed out to DisplayPort and VGA and same Green Blob. Has to be the logic board. Sad, monitor only 2.5 weeks from warranty. Dell wouldn’t honor. Know where I can get a logic board? Thanks for the response.

    Janet

    Comment by Janet — 03/10/2012 @ 22:07

  36. avatar

    Well, Janet – in that case you probably know much more than I do. Sorry to hear about the warranty! Never heard that logic boards were sold separately – but then again, I don’t know everything.

    Nonetheless, all the best of luck to you!
    Dr.

    Comment by Dr. Ivan — 04/10/2012 @ 19:00

  37. avatar

    Dr.
    I have the same monitor as yours (Samsung SyncMaster 206BW). It is two years old and recently has started this blinking at start up. Screen blinks on and off repeatedly as I try to power up. Multiple attempts finally get the screen going. Sometimes the screen will start blinking when I am online, forcing a shutdown and restart to get video display working again. My question is: If the capacitors are bad, wouldn’t this occur continuously? Why would it (usually) only occur at start up? Are you aware of whether Samsung has posted any information regarding this problem? Much appreciate your reply.

    Comment by Gary — 10/11/2012 @ 00:15

  38. avatar

    Hi, Gary!

    Thank you for visiting my blog!

    I am not entirely sure that your problem is entirely related to the screen. You mention that you need to force “restart” – I assume you mean computer reboot? In case this resolves the problem, perhaps it has also something to do with your video card overheating. Have you checked what temperature it is running at?

    Nonetheless, the behaviour you are describing is very similar to what I experienced. It is of course difficult to comprehend how these problems occur only during startup. I am no engineer, so take the following explanation with a grain of salt. All components behave differently at different temperatures. It might just be that half-broken capacitors need to get up to a certain temperature to work properly, while those that function properly are more tolerant to low temperatures.

    I am not aware of any information on this issued by Samsung. Their tech support department does not return my emails and I am far too busy to call them.

    Cheers!
    Dr.

    Comment by Dr. Ivan — 12/11/2012 @ 19:59

  39. avatar

    Hi Doc!!
    I have samsung syncmaster 2233sw LCD monitor yesterday when I try connecting my laptop to the monitor the screen goes snowy. It is still snowy when I connect to the CPU as well, its not showing anything even if I press the menu button on the monitor. Please help

    Comment by Abraham — 04/12/2012 @ 14:07

  40. avatar

    Hi Abraham!

    Not quite sure what you mean “connect to the CPU”, but to me it sounds like your monitor is not configured to select the correct source (which should be your computer) – which is strange, considering that the monitor should select source automatically. I am wondering, what type of connection are you using? HDMI? DVI? VGA?

    If the monitor shows snow even when you press the menu button (and there is no menu on the screen) – then take the monitor back to retailer, it is most probably defective!

    Dr.

    Comment by Dr. Ivan — 12/12/2012 @ 20:57

  41. avatar

    Hi Dr. Ivan! I hope you can help me out with my dilemma. I have a Samsung LCD Syncmaster B2030 purchased in 2010. It’s been doing great until a few days ago. Whenever I turn it on and start the computer, the screen has lines and it turns yellowish. It affects all the colors on the screen. Now I tried to fix colors on the menu and kept it off overnight but still the problem persists. O hope you can help me out. Thanks for whatever advice you can give me.

    Comment by Meg — 22/12/2012 @ 01:04

  42. avatar

    Hi Meg!

    It is most probably not an issue with cables or ports or software. Have you tried changing the caps? I might be worth a shot… Otherwise I wouldn’t spend too much time tinkering with the innards yourself. There are basically three kinds of problems you can fix on monitors:

    - capacitors
    - backlight (possible to repair, but difficult)
    - faulty cables / connections

    If all of these are not to blame, it is unfortunately easier to cave in and just purchase a new monitor (provided you can’t get your old one repaired on warranty).

    Dr.

    Comment by Dr. Ivan — 22/12/2012 @ 20:29

  43. avatar

    Hi Dr,

    I have a samsung 940 lcd monitor and after a crash voltage stopped working. No led was light up.I checked and found three capacitors to be damaged and replaced them. So after that the led became active but when i connected a vga cable from my pc couldn’t see anything and the led was blinking. After a while I observed that the monitor was showing the screen of the computer but was so so dark. No button from the front panel could do anything. The menu of the lcd was showing exactly as i described before. Any idea to help?

    Kind regards,
    Kyriakos

    Comment by Kyriakos — 18/01/2013 @ 10:05

  44. avatar

    Hi Kyriakos!

    It is probably due to a faulty backlight. You can of course try to replace it (there are a number of tutorials on this online), but it usually is quite a hassle.

    Dr.

    Comment by Dr. Ivan — 18/01/2013 @ 10:25

  45. avatar

    My 3 yrs Dell 19in monitor starts to burn in the upper left corner after a few minutes I turn on the monitor, it creates grayish screen on the part that’s over heats (upper left corner)and it starts to smell likes its burning electronics stuff. I open the monitor and check the inverter boards seems to be ok and put it together again and switch on, at first its ok but a few minutes it starts to burn again on the upper left corner. pls advice me on this. thanks in advance. I also notice partially melted plastic on the upper left corner.

    Comment by rldelacr — 31/01/2013 @ 09:15

  46. avatar

    Hi Dr. Ivan.
    First, sorry for my english, ’cause I’m from Brazil.
    I’m a electronic engeneer and like to much to fix electronic stuffs.
    I found your blog on the net and would like to know if you mat help me.
    I’m trying to fix a LCD philips monitor, model 190c6, and already make these actions:
    - change 6 electrolictic caps, where 3 of them were visually bad;
    - take out from the PCB board the 2 schottky diodes, type sb240. I verified both with the diode function of the digital multitester and the values presented were around 170 ohms at the conducting flow and “open” at the reverse direction. I decide they were good;
    - verified if the MOSFET transistors (AP40T03GH, an N-channel, and AP4415GH, an P-channel) installed on the PCB were in short-circuit with the digital multitest at OHM test: not in short circuit.

    After I changed the 6 caps, I thought all will work find, but it’s not go on this way. The initial symptom still is there: you turn on the monitor and after 1 second the screen goes to black.

    Maybe there are something wrong with the schottky diodes and/or the MOSFET transistors, or even with the backlights (the lamps)…?

    So I was thinking about to put some simulated load in place of the backlights to discover if one or both the lamps are bad, or if there are some malfunction in a particular inverter circuit.

    So, if could help me, I was so grateful.

    Thank you,
    Samuel.

    Comment by SamK — 19/02/2013 @ 02:15

  47. avatar

    hi Dr Ivan i have lg 2234s 22inc lcd monitor my monitor problem screen icons very very big not see all icons mean view picture very big im maked setting but not change again big picture only monitör work time no signal icon normal not big connect pc time screen view big picture what is this problem? vga card? or driver problem? i hope ur have a idea for me how fixed my monitor excuseme my english not good i hope ur understand me Muko Turky

    Comment by muko — 20/02/2013 @ 12:27

  48. avatar

    Hi rldelacr!

    Your monitor is not safe to use. You should never attempt to repair or use electronics that visibly overheat! You should buy a new monitor – or get yours exchanged if you still have a valid warranty on it!

    Dr.

    Comment by Dr. Ivan — 21/02/2013 @ 22:41

  49. avatar

    Hello, Samuel!

    To be honest with you – you probably know electronics much better than I do, at least judging by your description ;) Nonetheless, I have never heard that backlights would make the entire screen go blank – but since you’ve tried almost anything else, it might be worth a try!

    Sorry that I couldn’t help you any further, Samuel – good luck!

    Dr.

    Comment by Dr. Ivan — 21/02/2013 @ 22:47

  50. avatar

    Hi there, muko! I am sorry, I don’t quite understand what you mean – however it does sound more like a software issue.. perhaps drivers? Or it might be that you have to “auto-configure” your monitor through the on-screen menu?

    Dr.

    Comment by Dr. Ivan — 21/02/2013 @ 22:51

  51. avatar

    Hi, Dr. Ivan. My 2 yr Samsung Syncmaster 2223 has been flickering to black, and getting worse. Today half the screen was black. Sometimes it returns when I continuously hit the backspecer. I tested the computer with another monitor and it was fine. I have dissembled the monitor, and inspected the capacitors… None are bulging. Should I still replace them all? There are 4 270/50’s, 2 680/25’s and a 70/16. Or, should I look for something else? Thanks

    Comment by Albert — 22/02/2013 @ 00:16

  52. avatar

    Hi Albert!

    Well, I think you should try to replace them. Look at it this way – you do not have much to lose. As you have disassembled it already, your warranty is voided. The choice is therefore between throwing away the monitor, or spending 5 bucks and running a chance that it will be as good as new. And if not, well… It was worth a shot at least :)

    Dr.

    Comment by Dr. Ivan — 22/02/2013 @ 00:23

  53. avatar

    I am having trouble finding them

    Comment by Albert — 22/02/2013 @ 01:34

  54. avatar

    Greetings, Dr. Ivan.

    I just attempted to repair my Westinghouse LCM 22w2 monitor by replacing the bad capacitors. I thought that I had done a decent job replacing them, but when I tried to turn it on afterwards, the screen won’t turn on at all. I can hear some noise coming from the back when I plug it to power. Have you had similar experience? Is there any suggestions you could give me?

    Doug.

    Comment by Doug — 16/04/2013 @ 07:41

  55. avatar

    Hi Doug!

    Well, that sounds like you have either damaged the board – or placed one or more of the capacitors in the wrong polarity. If damage has been done to the power circuit when you turned it on, it would be dangerous to tamper with the innards of the monitor again, so I would suggest that you either send it for professional repairs (warranty is most like voided though) or buy a new one.

    Dr.

    Comment by Dr. Ivan — 16/04/2013 @ 07:59

  56. avatar

    Hi doc
    I have a Samsung bw226 lcd monitor, now what was happening before was the screen would come on display an image and immediately switch off and has been doing that for a while so ive now replaced the caps on the power board, correct polarity, voltage rating and capacitance rating, soldered properly and after plugging it in im still having the same issue not quite sure what to do from here pls help

    Thanx
    Dee

    Comment by Dee — 21/04/2013 @ 16:41

  57. avatar

    Hi I just found your site from Google.

    A friend gave me his monitor, which is the exact same model as the one I have owned since 2008.

    I turned it on but it has lines through the screen and is quite fuzzy. The pixels are very visible and there are hues of green, purple, pink, and vibrating colors on certain areas of the screen.

    Here is a picture of the bad monitor:

    http://farm9.staticflickr.com/8123/8684168557_3152550f90_k.jpg

    notice the lines through the icons at the bottom and the green at the bottom?

    Here is a picture of the good monitor:

    http://farm9.staticflickr.com/8400/8685287036_04d509857b_k.jpg

    The pictures don’t do justice to the bad monitor. It has lines all through it. Also that bright light in the middle of the screen is just the camera flash. Certain backgrounds also make it much more noticeable.

    Do you think this problem is bad capacitors? I love this monitor so having two WORKING of the same would be great. I don’t have enough money for a new monitor.

    Thanks!

    Comment by goat — 27/04/2013 @ 07:40

  58. avatar

    where did my post and reply go… I had some more pictures.

    Comment by goat — 27/04/2013 @ 20:42

  59. avatar

    Hi Dee!

    Then your problem lies elsewhere. It is rather difficult to do any further diagnostics just from your description, but from the sound of it the problem might lie with the power supply circuitry.

    Dr

    Comment by Dr. Ivan — 28/04/2013 @ 00:18

  60. avatar

    Dear goat,

    All posts are approved manually by me, so they will not appear immediately. The pics you posted look suspiciously like my monitor did before I replaced the capacitors, so it may well be that replacing them will help you too.

    Good luck!
    Dr.

    Comment by Dr. Ivan — 28/04/2013 @ 00:26

  61. avatar

    Sorry about that Dr Ivan I did not know.

    Can you look at these pictures for me and give your opinion if you have time?

    I posted these also at badcaps.net

    http://farm9.staticflickr.com/8401/8687877812_bcb0032f7e_k.jpg
    http://farm9.staticflickr.com/8254/8686761833_6470c32d6a_k.jpg
    http://farm9.staticflickr.com/8255/8686762609_f4ef943699_k.jpg
    http://farm9.staticflickr.com/8115/8686763487_c9c9779450_k.jpg
    http://farm9.staticflickr.com/8253/8687880926_1cb9712674_k.jpg

    Comment by goat — 28/04/2013 @ 04:18

  62. avatar

    Hmmm, from the pictures they look quite normal to me… Without any indication of which ones are bad, you might end up replacing all of them – which is both tedious and can end up rather expensive (since there are *many* differently rated caps, and you seldom can buy only 1 cap). Besides, you are never guaranteed a good result. So not sure I can help you out here unfortunately, I hope someone else can shed some light on the case – at badacaps.net or here!

    Dr.

    Comment by Dr. Ivan — 28/04/2013 @ 07:15

  63. avatar

    Your comment 38 to Gary amused me with its reference to half-broken caps needing to get up to temperature. My Syncmaster 206bw has been playing up for about a year now, getting steadily worse so that it just sits there blinking and blind until it gets outside help. I don’t trust myself to change the caps (yet!) but found I could get the monitor to work by playing a hairdryer over every visible orifice for a couple of minutes. Once my electricity bill starts reaching the cost of a new monitor I’ll try to follow your advice and change the caps.

    Comment by Peter — 28/05/2013 @ 17:00

  64. avatar

    My goodness, a hairdryer?? That is certainly a new one, Peter – I’ll keep that in mind the next time I have a dead monitor on my hands ;)

    Comment by Dr. Ivan — 07/06/2013 @ 20:27

  65. avatar

    Dr. Ivan,
    I am having a problem with a 17″ NEC MultiSync LCD 1980SXI monitor. After approximately 15 minutes, a 5″ wide vertical section of the monitor presents from top to bottom with changing colors(very vivid). It will stay there until the monitor is turned off and cools down. Could this represent a capacitor problem?

    Comment by R.J. — 07/06/2013 @ 23:14

  66. avatar

    Hi, R.J.! Yup, that sounds exactly like the problems I was having!

    Dr.

    Comment by Dr. Ivan — 07/06/2013 @ 23:16

  67. avatar

    dear pls help me i have samsung synyc master 920 nw lcd i changed all capastor and it work for 20 minute now again same problem after 1 minute screen go blanck and where i turn on off monitor its ok but only for 1 minute wht i should do fast reply plss ((((janudar ( at ) yahoo (dot ) com((((

    Comment by jann — 14/06/2013 @ 17:44

  68. avatar

    Hi jann! Then the problem is elsewhere. Perhaps heat?
    Dr.

    Comment by Dr. Ivan — 15/06/2013 @ 23:26

  69. avatar

    Hi:) i have the view sonic monitor. When i switched on, the screen shows only white colors with some lines on that without connecting the cpu. What might be the reason and how to resolve it?

    Comment by Abhi — 01/07/2013 @ 18:16

  70. avatar

    Hi Abhi! What do you mean “without connecting the cpu”? The reason can be pretty much anything, loose contacts, faulty board, drivers…

    Comment by Dr. Ivan — 01/07/2013 @ 21:32

  71. avatar

    Hi, eventhough i connect the cpu, same white screen.. Can’t u find the exact problem? Is is due to capacitors

    Comment by Abhi — 02/07/2013 @ 04:53

  72. avatar

    Hi Doc I have a 22in LCD hp monitor and it sometimes works great, but the times when it doesnt the monitor will become fuzzy and and be split flickering up and down on my screen, it also goes crazy with the colors purple blue and grey it does kinda alright with Black and white

    http://www.flickr.com/photos/99092409@N02/9320563180/ this is the HP 22in LCD

    AND this is the HPtouchsmart 610 quadcore my #1 computer (as far as the screens go)

    http://www.flickr.com/photos/99092409@N02/9320563334/

    Get back to me when and if ya can :) – S194

    Comment by Subterfuge194 — 19/07/2013 @ 10:55

  73. avatar

    Hi S194! Yup, that looks and sounds pretty much exactly like the problem I was having! ;)

    Comment by Dr. Ivan — 19/07/2013 @ 17:53

  74. avatar

    Hi dr-ivan! ;)
    I have a samsung LCD about 3 years old, and would love to have some help diagnosing it :)
    Here’s the deal: the tv restarts randomly (mostly between commercials – if I open the receivers menu, it doesn’t happen at all, and I can wait watching the commercials in a small portion of the screen). Sometimes it will keep cycling on/off with the red led blinking, trying to get on (the back light lits up), sometimes dies completely until someone pulls the power plug and places it again (AND in this case, sometimes you need to wait a couple minutes with the cable unplugged to escape the on/off cycle and start the tv correctly). No funny clicking noises, I believe the relay is a “quiet” type, I only hear the melody, even when it was new.

    A month ago, I opened it and the capacitors were all good (at a first glance). Replaced about 5 of them near a heat sink, should they be bad. TV ran great during commercials for a couple of days, then got the same as before. Opened it again and replaced ALL of the remaining electrolitic capacitors (except the very large fellow). Ran fine for a couple of days, then back on the same pain… I have electronics background, but would appreciate any ideas on what the problem could be, since on the web I only find capacitor-related posts…

    Many thanks for the help :D
    gabriel

    Comment by gabriel — 12/08/2013 @ 01:53

  75. avatar

    Hi Gabriel!

    This sounds perhaps like a recurring problem either due to heat (damaging newly replaced components), or perhaps poor grounding for one reason or the other (and in the latter case I would strongly advise touching it at all, far less disassembling it). In any case you could try to see wether there are any heat spots on the back panel, remove anything that might be covering the ventilation holes, move the TV away from the wall to increase air circulation. Failing that, you could always get a fan pointing at the back panel to try to cool it to see if it helps.

    Hope any of these suggestions help!
    dr.

    Comment by Dr. Ivan — 13/08/2013 @ 22:51

  76. avatar

    Hi Ivan !

    I have a problem with a LCD monitor Samsung SA850.
    At power on , appear on LCD some strange random horizontal lines on the right part of LCD.
    like this http://imageshack.us/photo/my-images/825/tbwb.jpg
    After 30 minutes with power on, lines disappear and monitor work normal.
    Power supply is a 14V/4.5A – is like a laptop power supply.
    In the all ports: DVI, HDMI, VGA – problem is the same.
    I change the cables, video card – same problem.
    Could be the external power supply ?
    Thanks !

    Comment by Steady — 26/08/2013 @ 21:28

  77. avatar

    Hi..
    i have dell 19inch monitor which works fine for past 5 years. two days back the display goes black and when i turn it off n on again it comes to normal, and after 2 sec it goes black. please help me

    Comment by Jilu — 08/10/2013 @ 19:36

  78. avatar

    Hello,my monitor have this problem.First of all when it starts can stay forever open(5-6 andmore days) without save mode.When my monitor is going on save mode the power light goes out and when i press the buton to open it cant.my monitor then stays out of power for 2days. Untill i finally after few attempts press the button and i she the light and monitor is fine after i she the light.i have my pc open like 2 weeks cause if i close it it will be hard to open themonitor again.i have seenmy capacitors and it looks fine to me. What should be the problem.

    Comment by michael — 17/11/2013 @ 19:09

  79. avatar

    hi
    my acer monitor went blank screen on me I changed 5 caps and was dissapopinted when I turned it on still same problem any ideas please

    Comment by eddie — 03/02/2014 @ 14:16

  80. avatar

    I Ivan,

    I have a acer aspire 7720g for the last month the colour on my LCD as been going fuzzy like one of
    those weird sixty’s films. Sometimes it last a few minuets or for hours, turning off the computer helps sometimes for that moment and other times it takes a lot of turning it on and off to get it to work there seams no logic to it since the next day or week when I turn it on its still fuzzy and if left on for a while the screen clears up.How can I fix it.

    Comment by G — 05/03/2014 @ 23:54

  81. avatar

    Followed your instructions completely to repair the same fault on my Syncmaster 206 and they were absolutely spot on! The pics and component list were invaluable. I now have a fully working monitor – thank you!

    Comment by Stephen — 20/03/2014 @ 23:43

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