Friday, December 16, 2011

Tips and tricks on repairing LCD monitors

If you are a student like I am, sometimes it just too expensive to buy new hardware. And why should you? There are many companies, faculties that throw away used non-working equipment. Here I will show you how you can repair used LCD monitors practicly for free. 

In the past year or so I managed to repair about 50 LCD monitors out of 60, that I sourced around my town. From my experience I can tell you, that you can have a working LCD monitor in under 20 minutes practicly for free with no profesional tools required.

LCD monitors are not that complicated as some of you think. They are made from 4 parts: LCD module, main board, switched regulated power supply (SMPS) and button board. 

From my experience, the main faults are:
- 85% faulty capacitors
- 10% faulty inverters
- 5%   other issues (faulty buttons, main board, LCD module, CCFL, FETs)

Fixing this problems is very easy and very cheap. You can get capacitors and buttons in your local electronics store. Inverters are sometimes a problem to get, but ebay will probably have the one you are looking for and its price is around 5$. 

There are many different brands of LCD. The most common are Samsung, LG, HP and Dell. And they are all more or less the same. You should also know the fact that many LCD modules are compatible. For example, I replaced an LCD module from HP to Samsung and it was a perfect fit. This is because the modules are basicly same dimensions and same LVDS connector for all types. Sadly it is not the same for mainboards and SMPS. But hey, SMPS can be fixed and main boards and LCD modules are very rarely defective.
 
LCD issues can probably tell you which part is faulty. So lets go to the symptons:

1. LCD lights up for less then 5 seconds, then it goes blank (check if you can see picture):
       - it could be dead capacitors on the inverter low voltage line (high probability)
       - it could be a faulty inverter (low probability)
       - it could be a faulty cold cathod flourescent tube inside LCD module - CCFL (very rare)
2. LCD power LED blinks but monitor does not light up:
       - it could be dead capacitors on the 5V logic line to the main board (high probability)
       - it could be faulty main board (very rare)
       - it could be a dead LCD module (very rare)
3. LCD turns on, the picture is fuzzy:
       - it could be faulty capacitors on SMPS (high probability)
       - it could be defective main board  (low probability)
       - it could be defective LCD module (very rare)
       - flex cables in the LCD module have a weak connection (very rare)
       - LVDS cable is defective (very rare)
4. LCD turns on, backlight turns on, but gray or white screen appears:
       - LCD module is defective (high probability)
       - poor connection of LVDS cable (very rare)
5. LCD emmits strange buzz sounds:
       - dead capacitors or inverters (high probability)
       - faulty CCFL (low probability)
6. LCD works ok, but sometimes it seems like that buttons are pressed for no reason (OSD menu appears):
       - faulty buttons (high probability)
       - faulty main board (very rare)
7. LCD appears to be completly dead (no LED signal light)
       - it could be faulty capacitors on the 5V logic line (high probability)
       - it could be the fuse on SMPS (rare and probably for a reason)
       - it could be faulty main board (very rare)

These simptoms can tell you very much of your fault. Now lets beggin with our dissasembly... I had a 17" Samsung monitor, with an issue number 1. 

LCDs are encased in plastic housing which is hold together with few screws and a click sistem. This is probably the tricky part of disassembly. When you remove the housing, carefully remove the LCD module. But before you proceed, unplug the CCFL cables from the SMPS board that hide behind a metal shield.


Metal shield

Unplug these cables

When you are finished with CCFL cables, unscrew the LCD module and carefully unplug LVDS cable from the module. Now you have a full view of the main board and SMPS.


Electronics

BE CAREFULL! The big capacitor on the mains voltage line on SMPS could still be charged. So make sure you discharge it before proceeding.

Now that you are done with that, unscrew the SMPS and look for faults. In most cases a dead capacitor is visible. But if there is no visual sign of a fault, replace all capacitors on the SMPS. This will fix all your problems in most cases. I also recomend that you replace all capacitors on voltage lines on SMPS even if they appear to be good.

SMPS

Faulty capacitor here is visible



Next use your multimeter and measure the resistence of high voltage side of the inverter. In my case the high voltage side of the inverter shows about  620 Ohms on both of the inverters. Because values on the both inverters are the same, I can assume inverters are OK. But if the value varries between the two inverters, the one with lower value is faulty. So you will have to replace it. You will most likely find inverters on ebay. 

FETs can sometimes be faulty too, but it is very rare. If you can see cosmetic fault of overheating, try replacing them too.

SMPS botton

High voltage side of the inverters


Button board


When you are done, put everithing back together, except for the plastic housing. Now you can plug your LCD to the mains and see if you get a NO SIGNAL screen for more than 10 seconds on your LCD. 


LCD appears to work :)


Now that everything seems to be OK, put the plastic housing back on, plug your LCD to a computer an leave it running for an hour. If no problems will accour. Then the LCD is fixed :)

Now you have a new LCD monitor for 0.15$, the cost of a capacitor

If capacitors are the case, the success rate is allmost 100%. If you diagnosed other faults, like main board fault, LCD module fault or CCFL fault, the cost of the repair is too high and you will have to search for another LCD monitor. Don't forget to store your working parts from a busted LCD monitor, becase they might come in handy if you try to fix some other LCD monitors.

Here you can see some other pictures of faults:

Faulty capacitors
Inverter from an 19" Samsung, faulty high voltage side CD
Faulty main board - no visible sign of a fault. Tried to change voltage regulators but no luck...
If you end up with different working parts of different LCD monitors and all the same size, lets say 19". With a little knowledge and some spare time, you can put together a working LCD monitor. But you will have to make your own housing, becase the SMPS and the main board will probably not fit in the original housing. That's how I made a 19" LCD monitor in my workroom, made from a 19" Samsung LCD module and button board from Samsung, SMPS from Dell and main board from HP monitor. But this will require some more electronics skills, because SMPS and main board power connector is in most cases different.
 
I hope this post helped some of your problems out there. If you have any additional questions, fell free to contact me by e-mail.

114 comments:

  1. If I could make a point. Every time I run into any electronic device that has some bad electrolyte capacitors I make it a point to replace all electrolytic caps. I've run into problems where replacing the bad caps just delayed the death of the other caps. My belief is that all the caps were installed at the same time at the factory, all the caps are just as old as each other, and probably have the same defect because they were bought from the same vendor at the same time from the same lot.

    ReplyDelete
  2. I agree on replacing all the capacitors, but it is also a rather large chance that only that capacitor was a weak link in a chain. My LCD monitor is still working when I replaced only one capacitor that was blown. And it keeps working for about a year or so. But I agree, if the LCD is in your own possetion you can open it and change capacitors when they die again... but if you are fixing it for someone else I always replace all the capacitors on the voltage line...

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  3. The capacitors die due to the proximity to heat sources, if you will try to follow the caps that die most frequently you will see that the ones close to heat sinks are the first ones. Besides replacing them there are 2 keynotes about the replacement (based on my experience). First is use 105 degree C capacitors and second use low ESR capacitors, sometimes described as power supply capacitors. It may cost a few cents extra, but it's worth .

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  4. Heat is not the main problem... It is the frequency of the power supply. They undergo alot of strees because of that and heat is also one of many factors. But I agree to go with more expensive and quality capacitors with low ESR and high temperature ratings. But buy them from a trusted distributer of electronic components, because here in Slovenia I came across with stores that offered quality capacitors.. Ang guess what I got? Plain medium quality capacitors (and were expensive too...) I suggest Farnell.. They are expensive, but at least you know what you will get...

    ReplyDelete
  5. Thanks a lot for this article. I have been collecting "dead" LCD monitors for a while and will have a go fixing them soon.
    Do you know how to fix a bright green vertical stripe on LCD? It appears only after a few hours of being turned on.

    ReplyDelete
  6. Sounds to me like a faulty LCD module... It could be loose contacts on flex cables between TFT panel and driver board (try stuffing some paper between TFT panel and metal frame of the LCD - you will press contacts to ensure beter connection) but this is very risky.. you can damage the LCD module for good... And it could also be a faulty driver ... but this is very rare..

    Anyhow... I advise you to change the whole LCD module... they are pretty much the same and the LVDS conector is a standard for all modules...

    ReplyDelete
    Replies
    1. NEVER stuff paper or any items inside any electrical items. This is dangerous and a fire hazard. Try gaining a new flex cable or new components

      Delete
  7. This seems to work perfectly for me. Just to note that not all caps fail as obviously as this, so replacing any cap thats not perfectly flat is a good idea. Also, if its a circuit board or inverter issue, you can get a kit with a controller board, inverter and such for about 30 USD - you will need to throw in a 12V external power source though.

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  8. Yes they don't, sometimes they look like they are brand new but they can still be faulty... That is why I agree with others... If there is no visible fault on the board, try replacing all the capacitors. And it is also true, that it is better to replace them all anyway..

    But I came across many times that capacitors on the 5V logic line were all perfect, and the ones on 12V line were all busted or another way around... That is why I don't replace all capacitors on the board, but replace all capacitors on that voltage line (there are between 1 to 3 of them for one voltage line) But I do that only if the fault is visible, otherwise I replace them all on the the 5V line and a 12-19V line for inverters. The next is probably the main reason for malfunction.

    ReplyDelete
  9. Thanks for the great tutorial. The probability approach is very pedagogical.
    Here is an issue I didn't se mentioned in your list:
    The monitor I plug to my laptop take 4 minutes to warm up and display. It doesn't do it with other laptops. Any idea on a check-list ? Thanks.

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  10. This one is interesting but I think that the problem is in your laptop and not the LCD monitor. Because if LCD would be the case, it should also need to "warm up" with other laptops. Check you refresh rate settings and resolution settings on your laptop.

    ReplyDelete
  11. What's about the case when LCD doesn't lights up at all and power LED remains unlightened?

    ReplyDelete
  12. It could be the fuse on the SMPS. If it is blown there was a resaon for it... So check the whole SMPS for possible faults... Then again.. it could be the capacitors on the 5V logic line... they were in two of my LCD monitors that I have fixed...

    ReplyDelete
  13. Many many thanks ! I had a dead 19" ACER LCD monitor and I was too lazy to open it ... then I read you guide.

    About one hour to disassemble the frame without breaking the plastic ... then 10 seconds to spot the two broken caps.

    A jump to the local store to buy 2 new caps (higher voltage, just to keep safe) and my old buddy works like a charm.

    Symptoms: completely dead, no led, no backlight, nothing.
    Cure: 1+1 1000uF 16V (now 25V) dead caps

    ReplyDelete
  14. Glad my tuturial helped you out. Yes sometimes caps can be in short circuit - thats why no led will glow and the LCD monitor appears to be completly dead...

    Stay tuned.. there will be many more projects to come... sneak peak - remote controling your computer

    ReplyDelete
  15. Thanks. Great tutorial. My LG Monitor appeared to be dead. All capacitors looked good. I checked voltages on main board input and values were really odd. 21V on line marked as 12V and 4V on line marked as 5V. After changing all capacitors, voltages are OK and monitor runs like new.

    ReplyDelete
  16. my 37 inch is black ut osd works looks like 8 bit colours do u think its the av bozrd or inverrter

    ReplyDelete
  17. OSD sometimes are 8-bit so I don't think the problem is in AV board. Can you describe more simptoms of the failure?

    ReplyDelete
  18. I have a 28" I-INC Monitor. The power light goes on when I press the power button, but there is no image. After about 3-5 minutes, the image appears on the screen within a split second (no gradual brightening). Then the monitor seems to work, but I have periodic flashes on individual horizontal lines, seemingly at random heights on the screen.

    I have looked at the various boards, but have not seen any capacitors that are bulging.

    Any thoughts as to what this may be?

    ReplyDelete
    Replies
    1. I tested some other aspects of the monitor. When watching video with considerable motion (i.e. movie), if lines get more and more garbled. Then, the entire screen goes blank for a couple seconds, and then comes back, and then goes blank, and then comes back, etc. etc.

      Delete
  19. Try replacing capacitors anyway... They could be faulty even if they appear OK. Next I would check the inverters if they are ok. Random flashes on horizontal line? Is that like 1 line or more? Different colors or just brightness? I would say that is the problem with voltage that is not stabilised. Also check the 3.3, 1.8 voltage regulators. Let me know how it went.

    ReplyDelete
    Replies
    1. Yes, I realize they could be faulty still, but I don't want to replace every capacitor on each board if that's not the problem.

      Horizontal Lines randomly throughout the vertical range ... it is like they temporarily go black.

      The voltage regulators are great.

      Delete
  20. These are some strange symptoms. Could you take a snapshot of you SMPS board? For starters I would recommend that you replace capacitors on the 5V line. Leave the ones for inverters alone... I think there should be somewhere between 2-3 capacitors for 5V line. It is not hard to find them and are probably marked on the SMPSs PCB.

    If you will replace those, and the problem will still be there. Then I'm afraid there is something wrong with the main board or the LCD panel.

    When you say the LCD goes blank.. .Does it restart or just blank? Can you see the backlight when it goes blank? And do these problems occour when you don't watch a movie? Do the colors look normal when LCD appears to function?

    ReplyDelete
  21. Sorry ... life got really busy. I will get back to this, but it may be a couple weeks. (FINAL EXAMS, Yuk!)

    ReplyDelete
  22. hello there,i have a same prolem,my monitor just flicks to black and my desktop image,i notice that when i push and keep pressing the button it stays on,but when i donw push it it goes black,does this mean that i have to change the button from that mini board or is something wrong whit it??

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  23. Looks to me like faulty capacitors on inverter line.

    ReplyDelete
  24. Really nice site I do say myself.
    I've been trying for a few days trying to find JUST a TFT LCD screen "Part# LTM170EX-L21" & not a whole monitor for my Samsung Syncmaster 730B 17.0" monitor.
    I almost decided to just get a nonworking cheap monitor & use it out of it.
    Its very aggevating!!

    ReplyDelete
    Replies
    1. You can try any 17" LCD module. It will probably fit will all connectors (LVDS and CCFL lamps), just the housing can be an issue.

      And thank you for a positive feedback :)

      Delete
  25. I have two Samsung LCDs, one where the baklight goes off imeddiately, and the other where it goes off after about 15 mins. For the one that goes off immediately, I bought a new power supply board which did not fix the issue. For the other, I have replaced all the capacitors.

    The odd thing is that if I plug the tubes from one board into the other board, they both display the same fault regardless of which board they are connected to. (switching off immediately and switching off after 15 mins). Does this mean the CCFLs are faulty? What would you suggest I do?

    ReplyDelete
    Replies
    1. Yes. This is probably the reason. CCFLs are faulty. If you have any other LCD modules (any size) try connecting it to your electronics and see if they light up.

      If you are willing to take a risk, try to disassemble your LCD modules and check the CCFLs. They appear very dark on the ends if they are burned out. In the best case scenario. Only one of top or bottom will be burned out. You can take one out of your second LCD module and install it in the first. Then you will have 1 working LCD monitor and one for spare parts.

      Delete
  26. The result is impressive after all the solutions you’ve come with. By the way, allow me to drop a few suggestions regarding the proper maintenance of LCD monitors. Cleaning them at least once in a while with the use of alcohol (isopropyl only) or water is acceptable these days. Avoid chemical based solutions like ethyl alcohol and acetone. =)

    ReplyDelete
  27. Hi Neoxy, great site, very good help.

    I call for your help. I have a monitor, Point of View 22", wich now does not works. It seems to be in situation 1: It works for 1-2 seconds and then blanks. Whenever I torn it on, the same happens, I can see my desktop, but only 1-2 seconds, then itself gets blank.

    I opened it and watched for a burnt capacitor or disconnected wire or anything suspicious, but have not found it. Everything seems to be correct (no faulty capacitors nor burnt elements).

    So, before I start un-soldering elements or buying new things, I recall your help as an expert. What/where do you think can be the problem? I attach the photos of it via my dropbox:
    http://www.dropbox.com/gallery/14855888/1/PoV-KTV22WA?h=b33268

    There are 3 different boards: VGA, PowerSource and HighVoltage. All capacitors from them look good. The panels works (at least for one or two seconds). What the problem is then? Do you need a more concrete photo?

    Thanks in advance.

    ReplyDelete
    Replies
    1. Hi again,

      Any idea where to start?

      Delete
    2. Hy

      Sorry for a late response, I'm on summer vacation :)

      First of all, when the LCD goes black, can you still see a very dim picture on it? If you do, there is something wrong whit the backlight part of your monitor...

      Follow my steps and measure the resistence of high voltage side of the inverters, if they vary too much this is probably the case.

      If the inverters are presumed OK, try replacing capacitors anyway (they can be faulty even if they appear OK).

      If this is not the case, your CCFL lights are burned out. This is very difficult to repair (replace), and a chance that you will get them is also very small. If this is the case, you need a new TFT panel with backlight...

      Best regards

      Delete
  28. I've just fixed monitor I've got for free and there was two problems. Blown capacitors on the 13V line and blown 3A fuse on power line to the invertors (probably blown when the capacitors broke).

    ReplyDelete
    Replies
    1. That's nice to hear. I hope it will work for a long time.

      If it dies again check the rectifier (or rectifier diodes) and flyback transformer driver, also check the capacitor behind the rectifier. (These were mostly main reasons why the fuse blows)

      Best regards

      Delete
  29. Cleaning the LCD monitor is relatively a simple process, which will only take a few minutes. Your suggestion is effective, Cory! Also, as much as possible, avoid ammonia-based or acidic window cleaners because it will make the screen discolored and dull.

    ReplyDelete
  30. Yes cleaning your LCD monitor is great with alcohol (I use a mixture of pure alcohol and window cleaner - non ammonia based). But it doesn't matter how much you clean it... this wont expand your LCD's life! The only thing that can expand your LCD's life is to keep your envirement clean (no dust, no moisture). Anything else depends on other factors... (quality the most)

    ReplyDelete
  31. I've been researching how to fix my LCD monitor & know the desoldering/resoldering of the caps (which I assume is the problem) is gonna be no big deal. What I can't find is a decent explanation of how to split the case. Almost every repair tutorial I've come across starts with the case already split or just a quick "remove the base & any apparent screws, carefully separate the case, then....". I have a 22" eMachines E211H. The base if off, the screws are out - what's the best "tool" to use to undo the clips & where's the best place to start (top, bottom, side, corner, etc)? Thanks for any tips you can provide.

    ReplyDelete
  32. I allways start at the bottom with a flat screwdriver, then I proceed with a peace of hard plastic. Every monitor is a bit different and you get a feeling for it after you open some.

    ReplyDelete
    Replies
    1. i also have a serious problem in my LCD unit.
      nabeel

      Delete
  33. Hi Neoxy,
    I need ur help in repairing my LCD unit of Yamaha PSR S550b keyboard.it has vertical lines on right side of display, when power is turned ON. These lines disappear after some minutes. And sometimes the whole diplay flickers and after waiting for couple of minutes, display gets normal. Can u plz tell me where is the problem, I have the service manual and I also have skills of electronics.
    thanx.
    nabeel

    ReplyDelete
    Replies
    1. This looks like the flat ribbon cables that go to the LCD module have a weak connection. This kind of repair is very hard and sometimes even trying to fix it could get it worse.

      You can read about this here:
      http://www.febalcdrepair.com/?title=tcp_tab_bonding&menuid=13

      I repaired one monitor with this symptom and what I did was, that I stuffed a rubber piece between a LCD module frame and panel so that this rubber peace was pressing the flat cable connections down, thus making a good connection. But to tell you the truth this was very hard to do and was also not reliable.

      Delete
  34. Hi Neoxy.
    So far, nobody described the problem I have: depending on the room temperature, my 6 years old monitor either takes 5-10 minutes to light up (the power LED blinking on-off rapidly) or needs heating with a hair drier. After that the blinking stops and it works normally. This problem started about a year ago and is not getting any worse.

    ReplyDelete
    Replies
    1. This looks like faulty capacitors. Replace all of them on voltage lines. It should work.

      Delete
  35. Hello, I am from India, Thanks a lot for this wonderful post. It saved my day, and I opened up my monitor, I see that I have a browned up FET inside the power Board . Can anyone Please tell me what is the number for the FETs used in ILPI-068 POWER BOARD one that is used in OMNITECH VW19 / OM19WD or Philips 190EW9 M99 LE19C3?

    ReplyDelete
  36. hai neoxy
    i have one lcd that screen work vertical half what the problem? pls help me

    ReplyDelete
    Replies
    1. I am afraid there is nothing you can do about it. This is a TFT panel fault (probably one of the flex cables connection that go from TFT driver to TFT panel is bad)you will have to replace the whole module.

      You can take the LCD module appart and try applying some preasure to flex cables and see if other part of screen appears. If you find this weak spot try stuffing some rubber between the housing so there is going to be preasure on it the whole time. But this is very tricky and often does not help. Then again problem could be internal (between the two glass sheets of TFT panel) then there is absoulutely nothing you can do about it. It could also be a fault in the driver but I have never encountered such a problem.. It was always the weak spot for such faults.

      Delete
    2. thanks a lot for the immediate response. thanks again and again

      Delete
  37. great article!! I have a 32" Samsung lcd tv that turns on for 2 seconds and then picture off with sound. I think one or more caps are bad and am going to try and replace. I have never done this before but it seems pretty easy. When I take off the back cover of the TV, I see 'Danger High Voltage' signs everywhere. Should I be worried about these if the TV is not plugged in? It has been sitting unplugged for about a week now. I am curious to know if I start unplugging the cables if I will get shocked? Any advice would be appreciated.

    thanks

    ReplyDelete
    Replies
    1. Hy. Sry for the late response. If you let your TV be unplugged for at least an hour everything should be OK.

      Delete
  38. help pls.. my vertu 16" led monitor keeps blinking a red light...no display...i check boards no burnd capacitors..

    ReplyDelete
    Replies
    1. hmm try changing them anyway, next check if the inverters and voltage levels are ok. Is maybe just power ON button faulty? Check that too...

      Delete
  39. Hi, I have a syncmaster 920nw monitor and it seems totally dead. I suspect it's the caps on the 5V logic line. The problem is, I can't locate them on the board. Are they the ones on the main board or the power board? Are they the ones that are rated for 5V or 16V?
    Here is the link with the schematics for the monitor: http://www.eserviceinfo.com/download.php?fileid=62714

    Any help appreciated!

    ReplyDelete
  40. They are the ones on the power board, and are rated at 16V, but I suggest that you replace all of them on the power board. On the 5v logic line and inverter supply.. (rated 25V)

    ReplyDelete
  41. So the only 16V rated caps are on the main board. The majority of catalytic caps on the power board are 25V. The exception is the biggest one that is rated at 450V. I suppose I should change the 25V first and then see what happens?

    ReplyDelete
  42. i have Dell 198WFP monitor situation looks like 1. LCD lights up for less then 5 seconds, then it goes blank. In my case monitor Power Light lit up properly and display come for 2 seconds and then blank nothing, Power Light lit proper BLUE.

    ReplyDelete
  43. I have a monitor about 4 years old, it turning black while working, but the indicator light still on. follow some advices I find tow 8 pin chip (from inverter to capacitor area) got brown spot around them and a few capacitor showing bad (top pop up), these chip name : BD6N2B, I could not find them even substitute from NTE (chip vender).
    I replace all bad capacitors but the monitor still dead only the power light on. Will you give me some guide about this problem and how to get those chips. Thank you a lots

    ReplyDelete
  44. Thanks for provide a great tips about LCD.
    Thanks Best LCD screens in london

    ReplyDelete
  45. Thank you for these tips for the LCD repair.It is very helpful :)

    ReplyDelete
  46. Thank you so much for this great tutorial! I had a great 19" monitor going bad(HP vs19e), the screen just went black one day. So I found your tutorial about the capacitors going bad and I opened it up and saw they had busted caps. So a few days later and an order from mouser I had the monitor back up and running :D

    ReplyDelete
  47. Hello there, I have different trouble on my Vertu 19", normal power on it is ok, but in few second turn off the light. I measure the voltages out in secondary power is 13.3 volts, when turn on again the power the voltage is 12.1 volts then off light again. I replace the 4 caps 1000 microfarad/16v and 1000 microfarad/25v but nothing's happen. what is the other solution for this trouble... thank for this site/link.

    ReplyDelete
    Replies
    1. Are you sure there is only 1 capacitor rated 25V? Should be at least 3. If you find them replace them too. Otherwise check the inverter resistance on high voltage side like I described. It could also be a dead CCFL tube.

      Delete
  48. Ah! thank you i solved my problem CCFL tube near to busted, I replace it then never off light now. this link is very helpful...

    ReplyDelete
  49. Hi there I have samsung syncmaster 633nw.
    Whenever I turn on my pc, the monitor turns on but no display, the screen changes colors from pure black to white, red, green gray. I cant even access the osd menu whenever i press the menu button. the led light is steady fyi.

    Can you tell what might died inside my monitor?

    Many thanks in advance

    ReplyDelete
  50. Hi, I'm the one who asked about the Samsung Syncmaster 633nw. I just want to add that sometimes the monitor works yet sometimes it doesn't. Hope to hear from you. Thanks.

    ReplyDelete
    Replies
    1. Hmm this is a tricky one. Did you try your monitor with another computer? Maybe the graphic card has issues? Or there is a weak connection in VGA cable. Try these two options first.. and if the problem still exists there could be a fault in LCD mainboard or LCD panel... then there is nothing you can do to fix it..

      Delete
    2. Hi

      Just a quick update. I opened up the monitor, and cleaned the insides. I removed the LVDS cable and replaced it back. I'ved check if there is a blown capacitors and found none. Put it back.

      AND to my amazement, It worked!
      It has been working now for the past 3 weeks!

      Thank you for this blog for giving me the courage to open up my monitor. :)

      Delete
  51. very nice tutorial i am learning here, my problem is on NEC nw900 upon powering on white screen appears no picture or logo then it will off but the power led is orange and steady not blinking, I tried to open and check for bloated capacitors but nothing found, can you help me identify the problem and a possible solutions, thanks and power.

    joey from the Philipines

    ReplyDelete
    Replies
    1. White screen is probably a dead LCD panel or poor connection to it. Steady orange led means the monitor is in idle state (powered down, no signal). Try connecting monitor to a computer, if you see a steady green led, then mainboard of lcd is OK.. if you still have white picture, try replacing LCD panel.

      Delete
    2. i tried connecting it to cpu and you are right sir standby mode came, a 5volts supply flows in the T-con board once powered on and it drops to zero volts once the white screen disappears, ill try soon your recommendation of installing new lcd panel to finalize my findings.
      Lastly, may I know are the causes of faulty Lcd panel in order to avoid from recurring from my other monitors sir? thanks.

      joey from the Philippines

      Delete
  52. This comment has been removed by a blog administrator.

    ReplyDelete
  53. I am always looking for this type of blog. It provides a very useful services manual and pictures...After reading this blog, I becomes more capable to handle LCD monitors.....LCD Service.....

    ReplyDelete
  54. Thank you for this article. I just happened to get a free HP 17" monitor yesterday along with a couple of junk PC's that I was getting for scrap metal. I plugged up the monitor and the screen went blank after a few seconds. Reading your article, I felt it was worth a try and replaced 3 caps that looked to be bulging a bit. The monitor is now working for the last 15 minutes. I'm sure this has fixed it. Thank you!

    ReplyDelete
  55. I would be interested in seeing if you know why my westinghouse lcd died while watching it and when I remove one of the ribbons on the back the tv comes on but half the tv is dim

    ReplyDelete
    Replies
    1. Could be anything... should see for myself... sorry

      Delete
  56. My TV only outputs sound and no picture i sent it back to the retailer i brought it from and they said it was water damage and sent a picture of the effect board, LG spares said this board was the PCB Assembly Sub, the retailer is telling me the LG LCD TFT Module needs replacing? Could the PCB Assembly Sub just be replaced?

    ReplyDelete
    Replies
    1. If you are talking about the PCB on TFT panel... this cannot be replaced.. I also doubt this is the case. But then again I would have to see it for myself to give you more info.

      Delete
  57. Hi Neoxy,

    I've got a 24" Samsung BX2440 which while i was using it one morning just 'died' and wouldn't turn on again, no lights, no image. Nothing :(

    I've inspected all the capacitors for visible bulging/leakage but can't see anything wrong with them. I also checked for any fuses but couldn't see any (there are wires which i think might be fuses but they all look fine anyway). I'm not sure what to try next as my electronics knowledge isn't great. Is there a way to find the schematics of the boards or the expected values of different points i can test?

    Thanks!

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    Replies
    1. There are no schematics, but you can take pictures of the power board and send it to me via email and I will point out where the problems could be.

      Delete
  58. hi, Great Site!!
    I've fixed a couple lcd's thanks to you, but now I have a wierd problem.

    samsung synchmaster, 2007. The top 1/4 to 1/3 of the screen is lighter and brighter than the lower part. And now for the triple whammy: when I wave the pointer across the lower part of the screen, you see normal pointer travel. when I wave it across the top part, the pointer leaves a trail!! Also, when I move a window down on the screen, the top part leaves behind a ghost for a second or so!

    This happens on different computers, so it's not the computer's fault.

    Really interested in what you think!

    Thanks,
    Aaron

    ReplyDelete
    Replies
    1. Could be poor connection of flat cable from LCD panel board to glass TFT panel, or the LCD panel driver is faulty. Try plugging your monitor up to another LCD panel... doesn't matter if it's the same or not... they all have LVDS cable connector. If the image will be ok.. then the panel is a gonner... you can not repair this.

      You can also check if the CCFL light tube on the darker side is faulty ... If it is... this could also be the case because of interference from high voltage source.

      Delete
  59. Great article...thank you so much for sharing your knowledge...very helpful..keep it up!

    ReplyDelete
  60. Nice blog created by blog director it’s very informative and template is according to blog theme. I would like to come on this blog again and again.lcd screens

    ReplyDelete
  61. Hi, Thnx for the article.

    I have a strange issue. All new LCD monitors dies after 1 month or less with my computer. Evn My Bravia TV. All are getting power board failures. I cant undestand why. Earth wire is working as well perfectly.

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  62. Hey there, I would email but I do not see one.
    I have a problem with my monitor where the bottom 1/3 is all glitchy lines that flicker and bounce around. I have checked all caps and do not see an issue for Ive replaced those on previous monitors. I have checked connections for ribbons and cables and that did not solve the problem. I also tap on it and wiggle the cables and nothing happens either so no loose connections is evident. Any ideas for me??
    Thanks

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  63. Thanks, Neoxy, for the great post. I too am not afraid of tinkering, just being a bit of uncertain in this case.
    If you can spare a minute, can you tell me a quick and affordable fix, if there is such, for weakened brightness and/or contrast levels?

    Thanks,
    Huba

    ReplyDelete
  64. hi i need help, i change all the capacitor my lcd monitor except the the big one, but after 3-5hr use its turn back again to its problem turning on and of, i replace the capacitor almost 3 time and it after use it will back again, can any one help me with this..the original capacitor i remove there in no sign of faulty, but i did not test it in multimeter.
    capacitor:
    1000uF 16v - 2pc
    1000uF 10v - 1pc
    330uF 35v - 2pc
    47uF 50v - 2pc

    BenQ G900HD 19" LCD Monitor

    ReplyDelete
  65. Hi, I have a 5 year old samsung 2253nw. It works just fine, but lately has developed that unbearable high frequency whine on lower brightness levels, dissapearing at 85-90%. Of course I can't use the monitor much at that brightness, it kills my eyes.

    I opened it up and found no bad capacitors, not a single one had bulged on top. But anyway I went ahead and changed some of them, thinking that they may have started to dry out after such a long time, and under that kind of heat (some heat marks around some components...). It seemed to help a bit.

    There are two groups of 820 uF 25v capacitors I didn't replace because I can't seem to get that value, is it fine if I replace them with 1000uF?


    What else could it be? Some kind of coil gone bad? I don't want to trash such a nice LCD just because it's gotten unbearably noisy.

    Thank you very much.

    ReplyDelete
    Replies
    1. Well, after giving the PCB a good look, these 820 uF seemed to be doing filtering, so I changed them to my 1000uF replacements. Monitor is working fine, maybe a little less whining now with all the capacitors changed.

      I also glued every single capacitor to the PCB or to something else with some silicone, that took care of some of the whine, but it's still there. It's funny, if I play around with the monitor, hit it lightly, press on it -you get what I mean- I can get it to shut up even at, for example, 50% brightness or lower!!

      So I guess there's something in there that is in need of some pressure. I'll try to do the same experiment with the monitor opened up and running and try to pin down whatever that is and glue it down.


      Thanks, anyway! Lots of good information here.

      Delete
    2. Uf. This buuz could be the inevrter or transformer fault. It could also be the problem in CCFL lights. I encountered some of these problems before, but i could never get them to shut up like you said :)

      Delete
  66. Hi there,

    Thanks for your great help. Now I have my LCD screen working after replacing 4 dead caps.

    I tried the same for another LCD TV screen that has the same issue. It worked. but the current issue (it works fine for the 10 mins then screen goes blank and back-light got off) I measured the voltage coming out the12V pins, It get increasing till 14.5.. at this point the issue happens. What do you think the problem? What could be damaged rather than caps? I aslo measured the output voltage of the 12V transistor... It was the same 14.5V

    Could you advice? thank you so much! :)

    ReplyDelete
  67. This comment has been removed by the author.

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  68. Hi, thanks for your tips....in my case the Lcd Monitor work fine but with a pinkish color, the white is pinkish. I changed the cable VGA, another PC, I checked visualy components of mainboard, SMPS, and i cant see what happening. When unplugged the VGA cable, the OSD menu color is normal. could you help me? Regards,

    ReplyDelete
    Replies
    1. I came across this problems a few times. And the only two reasons i know is a faulty CCFL tube that glows white/pinkish and a poor connection on LVDS cable from mainboard to lcd panel.

      Open a large picture on full screen that is white and see if the color is even across the whole screen. If it is the problem is in LCD panel or connection to it. Maybe the voltage levels (5V and 3.3V) that supply the panel could be poor too.

      If you see just large sections that appear pinkish and other sections appear to be "normal" then the problem is in CCFL light.

      Delete
  69. This comment has been removed by the author.

    ReplyDelete
  70. Hello. I appreciate you're replying to everyone who has problems with the LCD. In my LG, the speaker minijack broke into the rear entrance of the screen. I got it out with a drill Dremmel (very small tip). Before drilling it, I dismounted the screen to see if I could get it out with a pin.

    Well, the fact is that when mounted, the screen goes blank. Would I recommend you buy the LCD Module and change it directly? I have checked the cables and superficially seems none broken.
    Thanks a lot.

    ReplyDelete
    Replies
    1. Maybe you damaged the board when drilling? If you can send some pictures to my mail I can gladly help out. But until then I can't help you because I really don't know what happened and what is the connection with speaker minijack.

      Delete
  71. A High Bright LCD Displays is the abbreviation for Liquid Crystal Display monitor. The quality of the images produced in an LCD monitor is high and it has high brightness and contrast levels as well.

    ReplyDelete
    Replies
    1. Got two dead monitors, one's a 22" Acer 2216W and shows a faintly white screen, no video signal even when plugged in to various cards/computers-- as though it's still off but the backlight's on at 5% or something, it was off/standby/off/standby/etc, bad caps, replaced the power board with the same model one, and it stays on now but that screen issue is a new problem.

      The other one is a Viewsonic VX2235WM and on either VGA or DVI input, turns on, then goes into standby about 15s later, screen stays black, and the menu/etc buttons don't seem to work, just the power button.

      My question is, since they're both 22" montiors with the same resolution (1680x1050), is it possible to take parts from one monitor and combine it with the other, to make a working one? would the acer panel be compatible with the viewsonic power/lvds cable/etc for instance?

      Delete
    2. Yes panels are compatible if resolution is the same.

      Delete
    3. hi,
      i hava LG 42 inch TV model LG 42LN5120 . the screen broken and full unit was replaced by company.
      i opened up faulty unit and removed broken lcd module,light filters and found led light source which is ok.

      can i use this led panel as light source in a room or open area?

      it is better use then to throw it in dustbin!

      how much voltage should be applied at led connectors?

      Delete
  72. Hi Sir, i have a problem on my acer's lcd screen right now. Right after turning it on , this appears on my screen.
    http://shiningblogger23.blogspot.com/2014/03/my-laptops-lcd-right-now.html

    Vertical colored lines are being displayed. What do you think is the possible problem and how can i solve it . Hope you can help me. Thank you very much.

    ReplyDelete
  73. very informative.

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  74. CCFL commonly faulty these days. Replacement was often horrid but tubes are now not readily available. Last resort frig the ‘timer delay’ over-voltage protection on the controller chip (OZ9938 etc) - bridge the capacitor. It will eventually fritz, likely the Royer transformers will burn out, smell a bit, wreck the inverter board and blow fuses but nothing to lose. (No It won’t go up in flames.)

    ReplyDelete
  75. Great article ...Thanks for your great information, the contents are quiet interesting. I will be waiting for your next post.if you want more information visit Monitor Repair Toronto get more details. Click Here

    ReplyDelete
  76. There is no doubt that the high brightness display does offer notable advantages. The first benefit is the output can be up to three times as much light as a standard digital display.
    High Bright LCD Displays window
    Thanks for sharing...!!!

    ReplyDelete
  77. hi, i have a samsung lcd 17in. i already replaced the capacitors and fuse (fusible resistor). after replacing components i've turned on the power with out connecting to my computer and it works displaying no sync signal. but when i connect to my working computer the fuse keeps on blowing...

    ReplyDelete