LCD Monitors

[Mechanic688]

Hi Guys, My friend scored about 15 used 15"-17" LCD monitors from a company that told him they were hit with a power surge and were bad. Well, with not a lot to be made off of LCD's by scrapping, we did some researching and found out that 9 out of 10 LCD's just blow out a few capacitors and so we replaced the cap's in one as a trial and it works perfect. We have around $4.- $5. dollars invested in them for new parts, but the used monitors will now sell for $ 30 - $50. each. That's a whole lot better than a dollar or two from scrap. I just thought I'd let you guys know that what you think is junk may not be,,,LCD TV sets seem to have the same problems. You just have to have a little experience trouble shooting and soldering electronic components. I hope this helps someone,,,

[Saroro]

Is that all there was to it? Desolder the old ones, and resolder the new ones?

[BigRyan]

That is good to know, and sounds pretty easy. Nice score!

[Pcbmine]

Yeah that is usually the problem with them. We have a guy that is a retired army man that comes by and buy all of ours..He has a shop and all they do is refurb the screens. We usually drop about 500-1000 bad ones on him at a time and he says that most of them only have a .05 cent capacitor that is swollen and he fixes them. We don't have time to do this kind of stuff but maybe in the future we will and cut out the middle man. He says it is getting harder and harder to move the screens though.

[Mechanic688]

Is that all there was to it?

To make a long story short, Yes, We just found the correct values, with the high heat value and ultra low freq noise and swapped out about 4 caps and that one came back up. We have since ordered the correct components online for the best price. Some of the caps you can tell because they are swollen or look like their leaking. We're going to replace the 4 or 5 common ones that blow instead of spending two hours troubleshooting for one or two bad ones. We call that a shotgun fix. We had one that has a bad inductor or something like it; we might make that one a donor. Just a note, you can't just buy the cheapest caps you can find, they won't work well or for long.

[Saroro]

wow, thanks! I'll keep that in mind. Do the caps have markings on them as to match them up, or is it in a manual somewhere?

[Mechanic688]

Saroro, check this out when you have a little reading time, and they sell the parts in bulk or as a package. Bulk is cheaper if you have quite a few.
http://www.badcaps.net/forum/index.php

yes the caps all have markings, like 220mfd 25volt, 470mfd 25volt, You can go up in value without hurting anything but you don't want to go down in value. These need to be 105c caps. cause of the heat. Standard caps. are 85c. Also there apparently is a noise generated in these monitors and these caps have some kind of rating for low noise. Might open up a little better market for those of you that are comfortable with soldering electronic components.

[Mechanic688]

Just a quick up-date on the monitors, we got the parts in that was ordered and so far my friend has 10 monitors up and running. Sure beats a dollar or two from the scrapyard,,,

[JunkyBusiness]

did you replace ALL of them or did you trouble shoot to see which ones were bad?

[Mechanic688]

We're going to replace the 4 or 5 common ones that blow instead of spending two hours troubleshooting for one or two bad ones.

We double checked them under a magnifier light to see the damage done to the cap's on the board. The damage was visible
with the magnifier light. Some were swollen and some were leaking slightly.

[easyrecycle]

We do LCD repairs here in our shop. To know what ones need to be replaced by looking on the tops they will be domed not flat. The ones that have small cuts in. Look at the little cuts are they deep or shallow? if they are not the same as the others around it then they are no longer good. And you dont have to remove the solder on them just WARM it up (not burn) so that it will brake lose then do the other side (leaving the solder on the board) then when you go to put the new one on you can rewarm the solder. Make sure you put the + on the + and the - on the - it DOSE matter on how its installed.

The other things that can make a lcd screen not work is the led light. So once you did the first repair an it still dose not work, then you need to find out where the led lights are on that screen take them off an replace. Again another very cheap fix.

Desktop, laptop an tv LCD screens are pretty much all the same. But the tv screens have more things on there because a computer screens only shows one item (the desktop) where the tv screen is set up for more than one tv show/video games an so on but all in all its the same deal.

[Mechanic688]

And you dont have to remove the solder on them just WARM it up (not burn) so that it will brake lose then do the other side (leaving the solder on the board) then when you go to put the new one on you can rewarm the solder.

Easyrecycle; One of the first rules of electronic repair is you suck the old solder off the board because you never want to reuse contaminated solder. It makes for a terrible solder joint, not smooth looking. Makes what they call in the business, cold solder joints! Just my opinion,,,

[easyrecycle]

Mr. Easyrecycle; One of the first rules of electronic repair is you suck the old solder off the board because you never want to reuse contaminated solder. It makes for a terrible solder joint, not smooth looking. Makes what they call in the business, cold solder joints! Just my opinion,,,

True, But those who dont have much exp can easy burn the board an or get solder every where. So unless you have alittle bit of exp under our belt you can get by with "cold joint" I can tell you..first time I tried...I got a dap of solder an by the time I tried to get it off an this an that...i caused a good bit of damage.

Play with scrap..something you dont care if you kill it or keep it simple.

[Mechanic688]

Easyrecycle; I have around 20 years experience in the electronic field, 10 years of that I owned my own retail store with a full service repair center. Blow your smoke up someone else's skirt, I'm trying to school those that want to learn, the proper way to do things, not half a$$ed. Thank you,,,

[jLr]

Mr. Easyrecycle; I have around 20 years experience in the electronic field, 10 years of that I owned my own retail store with a full service repair center. Blow your smoke up someone else's skirt, I'm trying to school those that want to learn, the proper way to do things, not half a$$ed. Thank you,,,

I am in the same field. If you flux the used solder most of the contamination will be removed from the solder and can be brushed off of the board with alcohol.

[bluemeate]

gd it, trying to troubleshoot my monitor and all the capcitors look fine.

Its an old monitor my dad was throwing out. i plugged it in and it was fine for a few days until last night i fell asleep with it on.
When i woke up the screen was bright so instead of hitting the power buttom i just laid it face down at the foot of my bed. I woke up an hour later and the screen wont stay on.

I turn it on and get an image for a second then it dissapears to a black screen with a very faint screen image in the back

but yeah, all the capitors are fine :/

[Mechanic688]

Blue; go up to the link I posted, that is a repair forum for flatscreen monitors and you might be able to find some similar symptoms as what you have experienced. If you do find some info on it, these guys carry parts single or in kits.

Badcaps.net - Badcaps Home

[JPete]

Easyrecycle; One of the first rules of electronic repair is you suck the old solder off the board because you never want to reuse contaminated solder. It makes for a terrible solder joint, not smooth looking. Makes what they call in the business, cold solder joints! Just my opinion,,,

Another reason to fully flow the old solder and remove it is to prevent the barrel of the through hole from shearing internal layer connections when pulling out the component. The boards you are dealing with are most likely multi layer.