How to repair an LCD monitor

I am often given a lot of LCD monitors that don't work anymore, and nine times out of ten, it's the backlight that goes out, but it's not the light itself. It's usually the power inverter board. I'm going to show you how to fix them because nine times out of ten you can fix them for just a few dollars, and a little bit of labor. Every monitor will be different, but many of them are very similar.

In this case, you'll want to figure out how to get the stand unbolted. The screws are hidden on this monitor, but not too hard to find.
It turns out there are two more screws to remove behind the stand. At this point, it will simply be a matter of pushing the bezel apart.

Typically, there will be hidden snaps all the way around the monitor and you'll just have to work your way around. Once you have the bezel off, you can start to see some of the innards of the monitor. You'll need to disconnect some cables, probably starting with the high voltage cables that connect to the fluorescent tubes. You may need to disconnect the main data cable that runs to the LCD panel.

Then you'll need to unscrew and remove the power inverter board from its chassis. All right, so I've got the power board out. Now, normally when I have a backlight go out on an LCD monitor, and I take the power board out, I usually see some capacitors that are either bulging or leaking or both. In this case, there are neither.

It appears all the capacitors, physically at least, were in good shape. That tends to suggest it's possible that maybe there is something besides a capacitor that's out, but I'm going to go ahead and replace them all anyway and, truth be told, even if there were only one or two bulging capacitors on the board, I would still replace all the capacitors just to be sure, so it's just kind of a good omen to see a bulged capacitor, because that just tells you "Yeah, this is a capacitor related problem for sure," so in this case it may or may not fix it. But at least I'll get to show you how to do it anyway, because even if - even if this is not a capacitor problem in this board, 99% of them are so you'll still know how to do it. I usually go ahead and make a note of the values of all of the capacitors I'm going to need, then I take a trip down to my local Fry's Electronics or Radio Shack and find the correct capacitors.

So let me show you how to desolder a capacitor. I'll start with this one. You'll need to find its solder joints on the bottom of the board. Now you can only heat up one leg at a time, so I usually rock the capacitor back and forth while heating one lead.

You can see that I've gotten one side of it free.
Now to do the other side. Now that I have it out, I want to remove the excess solder. First, I'll try a solder sucker, since that's the cheapest method. When that fails, I'll use solder wick to soak up any excess.

Now I can insert the new capacitor into place. Be sure the stripe lines up with the markings on the board! I. Usually bend the leads out on the bottom to keep it in place while I solder. Then I chop off the leads.

This board was designed for a second cap here, but was left off.
So for the heck of it, I'll add one there, which might increase the lifespan of its neighbor. Okay, so here's the finished board, and here are the old capacitors. Time for a test before I finish reassembling. Yep, looks like it works now, and here it is all put back together.

I'd like to just make one comment about buying the capacitors locally in a store, versus buying them online in a place like Mouser or Digikey. The capacitors individually are much much cheaper to buy them online: an order of magnitude cheaper. But the problem is, places like Mouser will typically want to charge you five or six dollars to ship your capacitors to you. So by the time it's all said and done, if you're just repairing a single monitor, it costs about the same to go down to Fry's or Radio Shack and buy the capacitors you need.

I'd also mention you know Fry's and Radio Shack also have a very limited selection of capacitors, and so in many cases you're not going to find an exact match. But what a lot of people don't realize is you can substitute in most cases, for example if it calls for a 15-volt capacitor, you're not going to find it at Radio Shack, but they may have, you know, 25-volt capacitor where you can always go up on the voltage. Now the capacitor might be slightly bigger, most cases it will still fit. So just remember, you can always go up in voltage to substitute, and in many cases you can even go up on the capacitance if you need to, because unless the capacitance is used for a circuit that does timing or something like that, in most cases having extra capacitance is not a bad thing, but in most cases you can find the exact number of microfarads you need.

The voltage is usually where you're going to have issues. So just just look for substitutions on that.
Anyway, I hope you enjoyed the video and let me know what you'd like to see next. Thanks!.