How-To Repair a Desktop LCD with Bad Capacitors
January 17, 2008 By Jeremy Brock
Desktop LCD monitors fail for a variety of reasons, the most common being bad electrolytic capacitors. If you are willing to invest the time you can fix your LCD for a few dollars in parts. For this demonstration I’m using an IBM ThinkVision 6636-AB1 however the same techniques apply to most desktop LCD Monitors.
Disclaimer:
A+ Perfect Computers, LLC, is not responsible for any damages to your device, person, or property. Computer, Laptop, or LCD disassembly and part installation is at your own risk. This Guide offers only suggestions for taking apart your device. The components inside your device are highly sensitive. Always ground yourself by using an ESD wrist strap or by touching a metal object while handling sensitive electronics.
- Symptoms:
- No Picture on Screen
- LCD displays picture briefly then turns off
- Tools:
- Soldering Iron
- Desoldering Station or Solder Sucker
- Phillips Head Screw Driver
- Spudger (Available Here and Here)
This LCD would turn on for a second then shut off. These symptoms are usually caused by a bad CCFL light or inverter board. After opening the LCD I did a visual inspection of the PCB looking for any dark areas, damaged IC’s or bad filter capacitors. The top of filter capacitors should be flat, bulging or leaking is an easy way to detect a failing capacitor. If available an ESR meter can be used to validate the capacitor is failing.
In this instance there are three bulging capacitors. Finding replacement LCD components can be tricky however replacement capacitors can be purchased at most electronic part stores. In this case we use mouser.com
To order capacitors enter the Capacitance and Voltage rating into the Capacitor Product Filter on Mouser. Look for the capacitor with the smallest diameter and length, prioritizing a smaller diameter over length if necessary.
Click on an image for a larger picture
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Remove the mount (not shown) and housing screws. The housing screws are usually located on corners of the LCD however they may be hidden under a rubber insert or sticker. |
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LCD's use plastic clips or snaps to hold the housing together. Use a spudger to gently pry the housing apart. Avoid using a metal screw driver as it will damage the plastic. |
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Remove the protective cover. Depending on the design you may need to slide the protective cover off once the screws are removed. |
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On this model the inverter board and power supply are on the same board 1. LCD CCFL Backlight Connectors |
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The top of an electrolytic capacitor should be flat. You can visually inspect capacitors by looking for a bulging top or dry brown crusty substance leaking from the capacitor. |
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Electrolytic capacitors have a solid line or dash going down one side for negative polarity. Installing an Electrolytic capacitor backwards can damage it so make note of the polarity relative to the board then desolder it |
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Make note of the capacity and voltage, in this case the 1000uf 16V and 470uf 16V (not shown) capacitors were bad. |
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Next solder the new capacitors in place making sure the polarity is correct. After soldering reassemble and test the monitor |
I have tow problem "children" here in my shop. the 2 items mentioned in the subject.
Sharp 30" LCD TV. I haven't changed them yet but I think this capacitor issue my be the problem with this unit. This model is one if the early Sharp LCD TV's. It's in 2 separate units, one unit is called the AVC System while the other is the Main (Display) unit. One day the "system" was turned on. the power lights would come on (turn Green) then after a few seconds the system would shut off and the power light would just turn RED of flash red. I think your "Find" about the electrolytic caps may be right on. After dis-assembly of the Main (display) unit, i inspected the caps on a couple of the boards and found a few with the tops bulged out like you described in the LCD monitors. Ill go through and change them and let you know if that solves the problem.
The Viewsonic VG930M has a different problem. I dis-assembled it and inspected all of the caps and found no obvious bad units. The problem is that when the video signal gos away, the back light does not turn off. The block Diagram in the service manual shows a block labeled ON/OFF and going into another block labeled Backlight Control Inverter. The Schematics in the manual that I have are terrible and none of them show the "ON/OFF" component let alone the Backlight inverter. I suspect that the ON/OFF unit is just (Basically) a transistor some where on one of the boards. I believe it's possibly one on the main board labeled either Q3 or Q6. I can find Q3, but NOT Q6. Any help with this Viewsonic would be greatly appreciated.
Thanks,
John
Thanks to you and this article, I fixed my mothers LCD monitor with some spare capacitors from my basement junk corner.
Thanks to you bro...
i got mine fix. thanks for the great help!!! this tutorial is very helpful!!! 2 thumbs up!
Hi, I have a IBM thinkvision L170 (6734-AB9), it have same symptoms it gives display for a second then display then blank screen with no display. I opened it up and checked all of its capacitors but non of them are even bulging slightly there backs are flat without any sign of leakage, Please advice What else can be the reason ? What i observed is one of the two identical components marked as T301 & T302 on board is slightly blackish from inside.
same problem monitor goes black after 2 seconds power ligth stays on dell desk top
the inverter boards are quiet easy to repair. if you did not find any pooped capacitor you should look on the bottom of the CAP too. it can be pooped on the bottom too.
the next thing to do is to change all the CAPs on the board, it will cost you nothing in terms of money (maybe one dollar).
Next you should check the transistors onboard and check their functionality.
Or buy same Transistors without testing (more few dollars)
If you can not find exact transistors in your dealer shop you may try google to find equivalent or closequivalent.
Next if testingthe Monitor fails look on the board a bit better for irregularities on the lines... if again nothing found... go and test the coils with an ommetter. You must read OM values that are printed on the coil. +-20%
If some coil is opencircuit (infinite OMs) or shortcircuit (0 OMs) you should change these too.
AND ONE MORE test is good too. to see if the monitor is working properly without light (maybe is not an inverter problem), you can turn a bright light into the lcd and see (in the background) the picture of your desktop or TV station.
Just fixed my ex-girlfriend's 19" Samsung LCD thanks to this tutorial. Replaced two popped 10v 1000uF capacitors on the power supply board, job done, she's very happy!
Did sshe give you a root for fixing it?
I own several of these with the same problem. The screen has low brightness and does not respond to the on-screen brightness controls. I am running these off traditional svga/analog cables. Any ideas? Thx.
that is your inverter/blacklighting if you open it up and put a flashlight behind screen and it is showing effects then you would need to replace the inverter...you could check caps there as it likely the power not getting through....worst case you replace invertor board for around 40.00
This article was very helpful, unfortanatly i replaced the bulged capacitors but the symptoms is still the same.
Also there is some black areas arround the invertor, how can i tested? to make sure is not working
waiting for your comments
Regards
Tiger
Just a few euros for new capacitors in store (I bought 10pcs from each type, it's not so expensive in Slovakia:) and my ThinkVision is working like before.
Thank you very much for this great manual.
Some specialists tell that mortgage loans aid people to live the way they want, just because they are able to feel free to buy necessary things. Furthermore, various banks give secured loan for different persons.
I was able to find the capacitors I needed from an old broken VCR in the garage. I fixed my 19 inch LCD and it works great! Thanks for the info :)
Worked like a charm on a ViewSonic VX715 !!
We purchased a couple of capacitors at radio shack, took the monitor apart, found two 1000uf/16v and replaced them with 1000uf/35v (all that radio shack had).
Soldered them onto the board and PRESTO! I am writing this testimonial while viewing it on the very monitor.
Thanks
Phil & Larry
(Washington, DC)
can i replace 1000uf 16v with 820uf 25v ?
I do not recommend lower capacity.
I've got a 19 inch AOC envision Lcd monitor, and as soon as I turn it on, it starts to frizzle , then, the desktop comes on perfect, but , yes there's always a but, the problem is , that my lcd has a fading from white to black horizontal line, or bar about 5 inches vertical x 19 inch across the screen. The rest of the screen shows perfect. Could this be a bad caps problem guys? PLease share your info....Thanks in advance.
I wonder if maybe the ribbon cable from the output board to the LCD might be loose or partly detached.
Greetings, I checked and double checked all cables. I even replaced most of the capacitors on the board, still, the line is there.. I took apart the screen itself, and tested the backlight and the screen, and it all tested perfect. Dont know wnat to do, anymore. i might juse decide to throw this thing away. My guest is that the chips that control the horizontal crystals alingment, is somehow malfunctioning, and changing these is a waste of money, cause I dont know how. well. thats it for now. let me know your views.
peace.
usualy when internal memory fails you get such an error.
First you have to re solder all the board to see if the problem is in the soldering. then test all the avvaible transistors....but usualy you will find the error again...
the smartest thing is to look for the price of new board, because i would not recomand a memori chip replacement
I have two ViewSonic VG2021m monitors that I love, and of course they no longer make them. When I started to turn my primary monitor on recently, it would buzz, the power light would turn blue, the screen would flicker, and then I could just barely see images on it. I could turn it on several times, and it would finally begin working correctly. I hated to think about having to buy two new ones (because they would have to match, of course), so I started looking to see if repair was an option. I found this article, which was a great help, but the best part was seeing replies from others stating how easy it was to perform this task. It gave me the confidence to try it. I'm fairly handy, but on home improvements. I've never worked on electronics or used a soldering iron. I was able to replace five capacitors, and now I'm typing this on my newly repaired ViewSonic. I rarely post online, but I wanted to say thanks to the person that created this article and for all of the others that replied to it.
I have this viewsonic lcd monitor sent to me by my sister with display defect and i was able to fix and after 3 months of use same thing happen as it was display will not come out and same capacitor were blown so i did fix it again and it work for about 2 months and recently the problem occur again this time only 2 capacitors were blown instead of 3 capacitors. Is there anything i can do like changing the values of the capacitors so that this problem will never happen again?
by the way i like your blog a lot and i learn a lot from you.. thank you.
You Must use Low ESR capacitors, that is why they are failing.
They normally have a different colored sleeve, not black like the others.
You cannot be assured that just looking at a capacitor will tell you if it is bad or not. Capacitors can *definitely* go bad and show no visual signs of it. Capacitors can fuse inside or slowly leak power, and still look fine.
My advice is if an LCD isn't working, just try replacing ALL the electrolytic capacitors on the power board with ones of the same microfarad rating and equal or higher voltage.
The voltage rating determines how many volts the capacitor can *handle* in terms of input, not how much it outputs! So it's fine to go over because whatever the capacitor is powering will draw however many volts it needs from the capacitor, so a higher voltage rating actually helps make the capacitor last longer.
However, if the voltage rating is far higher than the rating of the capacitor you are replacing, it can get really hot from holding too much charge, and might melt other components on the circuit board. Electronics are designed to get only so hot. Moreover, it may not fit on the board! So make sure you bring the board in to your Radio Shack and visually inspect the new capacitors to make sure they will fit. A good rule of thumb is not to exceed 2x the voltage rating of the capacitor you are replacing.
My Hanns Monitor packed up after 4 years of daily use
I switched it on and it kept rebooting it self twice a second...
I took it apart to find 6 bulging capasitors...
they were 470uf 25v 105c which I ordered from Rapid electronics
cost me in total £8 plus 45 mins soldering time
its been working perfectly for the past 4 days!!!!
I'm definatley glad I found this website
Cheers
Mike
After a year of perfect service, my AOC tv/monitor suddenly crapped out. The screen was discolored when displaying the loading screen, and many of the inputs had disappeared from the input selection box. When I read this guide, I decided to take apart the monitor. All of the old-fashioned caps were fine, but it turns out that one of the micro capacitors had popped off. It was missing, so I bridged the connection with a small drop of solder. The inputs showed up in the list again and the loading screen's color was back, but i guess I'm missing another cap somewhere because the vga input still displays a no signal error. Yes, I made sure my computer settings were correct.
Anyway, I parted with the monitor (via trash can) since I kept playing around and botched the mobo. It was a cheap monitor anyway. Just make sure that if you are not finding bulging caps, you need to look for missing micro-caps.
I have a 2001fpw and one day it just stopped working. Only flashes a startup screen real quick when first plugged in. I took it apart and replaced caps on the board where the power supply is but it still does the same thing. Before I replaced anything I did not notice any cap issues but did not know notice anything else that could be wrong. Do you think I should go ahead and replace the caps on the converter board? I don't think it is a backlight issue but I could be wrong.
Eh, i have an Acer Aspire 7730ZG with a monitor problem. Exception is, i can see an image, but it isn'T backlit. It's a laptop monitor. I need to repetitively press the backlight button to get the backlight on for a good period of time. My laptop doesn'T handle strong shaking, then the monitor pops black. Sometimes it's my charger unplugging, happens on the spot each time. Persists through restart. Under warranty. Any tips?
Got a solution?
Pass a mail to: icekhaos@hotmail.com
(Notice i cannot send a mail back.)
Listen to these people! This was such an easy fix, besides having to wait for the parts from overseas... Really though, this was only about a 5/10 on the difficulty scale, so go for it!
Hi...Love the article. I have the same "On 2 seconds then sleep mode" problem with a 25" Hannspree HF257. In doing a little research, I came across a suggestion that I turn the monitor brightness down, and it worked!
It takes some quick manuevering to get to the brightness menu while the screen is still on, but reducing the brightness is doing the trick as a temporary fix...I'm pretty sure I have some blown caps, and it makes sense to me that the brightness being lower would reduce the draw on the caps (brightness in LCDs is proportional to energy consumption/draw, so lower brightness, it stands to reason, would maybe let the thing function on half-baked caps!).
Luckily, my monitor is under warranty, so I'm not going to open it up/void warranty to confirm the issue is caps, but I'm virtually certain this is a cap issue...just thought the idea might help others who are in a bind until they can find a permanent fix!
This was a briliant idea. Thank you for the temporary fix!!!
I was wondering, I need to replace 2 16v 1000uf capacitors and am not sure how important the length and diameter are. Do they have to be exact or can they be shorter, fatter, thinner, longer?
Length and Width are an issue in most instances!
most are measured in MM (Millimeters) Mouser Electronics is a good source as well As Digikey!
Imagine 2 Capacitors side by side. Ever sat through a basketball game on bleachers with really tall guys in front of you and a bunch of people on your side(s). Maybe you where the tall one? Maybe you have to duck to get in the door? Same thing with CAPS.. Door frame in relation to a lid or cover that goes on the component may not close or fit. Caps closer together can cause more heat (look at range on caps when buying). Try to stay around 105' not the 85' cheaper ones. ALSO note the PIN SPACING on the RADIAL types of caps! Its a lot easier putting caps back on the board when they fit without bending the pins for the correct spacing!
Could the capacitor be the reason for my LCD switch problem?
I have problem with my LCD monitor (Samsung Syncmaster 910MP) switch to turn it on.
After the start od the computer the switch blinks for a quite a while. After stopping to bling it is necessary to try more than ten times to switch it on. After I succeed finaly to switch it on the monitor works well.
Thenks to anyone who can help.
Branimir
yes, I replaced 2 bulging caps on my power supply board to fix it.
hi nice tutorial
question about capacitors i need 3 1000uf 16v ones i looked around but only can find some that smaller in length mine are 10mm x 20 mm (with out he wire )the one si can find are smaller in length
can i put the smaller ones in if same values that the old ones that dont work
thanks great post
check this out :)
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=P13119-ND
or digikey.com searching part# P13119-ND
My monitor slowly giving up on me. One day he started to fade in very slowly instead of blinking on. This got worse and worse, and today, almost 8 months later, it got to the point that he was actually slowly fading out. I knew this wasn't a broken backlight, because the average brightness of my desktop had effect on the total brightness (white got darker when more text was on it).
Found this page and I was happily surprised the usual problems that old CRTs had are still around in the TFT generation. Just fixed 2 obviously broken ones with some old crappy capacitors I had lying around, lower voltage (but enough, according to board specs), lower capacity (but the broken ones still worked for 6 months, so it was worth a shot). The screen looks so perfect again, very bright, and turns on immediately again also. I still expect those caps to blow any minute, but they bought me time to order a good set, and write this.
So, thanks very much. My type of monitor (1600x1200) is rare and expensive atm, so this saved me a bunch, or the horror of a wide screen.
The problem with the LCD is that when you switch it on the benq logo displays then the screen goes black. After a few seconds the green light changes to orange. When I then switch on the computer the orange light changes back to green but no display. I've replaced the capacitors on the board although none of them looked bad but there is still no display.
Any Help?
Many Thanks!
Monitor would flash on for a second then black. Followed your instructions & replaced two capacitors, 470uf 16v and 1000uf 16v taken from an old monitor. Only found 2200uf 16v so I used that instead of the 1000uf 16v. The LCD screen is now working perfectly.
Glad you had this page online. Thanks again for expert advice!
You should replace those caps with the correct values, or closer.
(-/+20%) of the microfared value of the 1000uF which is 800-1200uF. Higher Voltage is typlicly ok. Always try to do this when replacing, also checking the heat range. Note 105' degrees for most applications of a general purpose radial cap in Monitors is good practice. Unless of course you need practice tearing that apart.
Remember these caps are like filters :) Just my 2 cents
Oh wow...... Those caps are going to fail. the "uf" reading is Microfarads. There is a 20% +/- tolerance for these (aka - you can use a 1200uf for a 1000uf) Technically. I would STRONGLY RECCOMEND THAT YOU USE THE EXACT MICROFARAD RATING TO REPLACE!!!!!! You replaced a 1000uf with a 2200uf cap!!!! I'm surprised that it worked at all. As far as voltage goes, NEVER USE LESS VOLTAGE, but you can use more. So, you can replace a 1000uf 16v with a 1000uf 400v if you want (you would never do that, but still) but you cannot use a 1000uf 12v replacement. The microfarad measurement should ALWAYS ALWAYS be identical, there is that 20% +/- threshold (which I still don't reccomend) but you are at 120% +/-!!!!! Please change out that cap for $1, please.
ur an idiot there are 2 different capacitors in that board
i have a 30inch Hp LCD and all of a sudden the images on the screen appear and disappear very slowly, it shows everything but it takes it some time. I checked the board and everything seems fine, is there a possibility that one of the large smt chips could be faulty, if so how could I check this
I am having problem with dell 17" monitor. The only difference is that it can stays on for about 30 mins then it shuts off. The green light is still on, but if you turn the power off and on it will come back on for about 3 to 4 seconds then goes blank again. If you let it sit for about 5 mins it will work for around 20-30 mins again. I dont know if it is the capacitors problem or not. Because I would rather repair dan bay new one.
Yes it might be a capacitor problem. The only way is to check by yourself by openning the monitor as explained in this post.
Maybe your capacitor is not very damaged, so it loses its load very slowly, then after some minutes it is so low that there is no display anymore.
Pics of bloated/burst caps :
Some times, it's not that obvious (no yellow/orange crusty dried liquid) :
Hi there !
My Hyundai T19D LCD monitor got this symptom (it displays picture briefly then turns off) but the is no bulging capacitors (I scanned the board with a magnifier for nearly an hour ,EVERYTHING looks fine).
So what can it be ?
- I tested my monitor on few graphic cards on several PCs and I always get the same problem so I'm sure it comes from THIS monitor.
- I also checked and tested the wires : no problem
Can someone help me please ?
Hi all,
First of all thx for the tut.
I have a DELL 2005fpw and i have is disassemle on mu desk... and cannot find leaking or bloated caps.
Please help!!!
Thank you in advanced!!
Cristy
I just replaced 5 bloated capacitors on a Dell LCD power board. Worked like magic.
Couldn't be easier. I've got a shelf full of other dead LCD monitors I'm going to try as well.
Thanks for posting this fix Jeremy!