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:
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:
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:
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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.
Soldering equipment is of course also required. Here is a list of miscellaneous equipment I used along with a picture of the tools:
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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.
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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.
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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:
Conclusion
If you have any thoughts to share about this article – or perhaps having trouble with this procedure – feel free to leave a comment!
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
@Ste: I’m very glad it worked for you!
Comment by Dr. Ivan — 02/11/2010 @ 14:25
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
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
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
My pleasure, Dave
Comment by Dr. Ivan — 11/11/2010 @ 18:33
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
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
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
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
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
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
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
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
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
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
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
hi??
Comment by cutty — 31/01/2012 @ 17:28
Hi, cutty!
Comment by Dr. Ivan — 01/02/2012 @ 08:49