Do you have a LCD monitor that turns on but has no picture? Does it display for only a few seconds than go blank, or maybe it just turns off completely? I've been seeing this problem more and more and I find myself doing the same repair over and over again. Thats right, I'm talking about the power inverter.
The power inverter is a power supply that takes the low voltage that runs all the logic and steps it up to around 600 to 800 volts with an even higher initial start voltage. It does that in order to run a cold cathode flourescent lamp (CCFL) that illuminates the LCD panel itself.
These inverters seem to be a weak point in LCD screens and my experience is that they fail most of the time because the electrolytic capacitors failed, or filter caps. There are usually 2 or 4 caps that range in value between 220uf to 1000uf and I've just made a habit of changing them. If you're failry proficient with electronics you might save yourself a lot of grief by changing these first. They're usually pretty easy to spot because they'll be around the input side of the inverter board and they'll be the only caps on that board with that range of value.
Some monitors have more than one inverter board and some have the low voltage power supply on the same board, so it will take some understanding about DC electronics to do this repair. But talking from experience, I've saved many screens this way with only a couple of dollars in parts.
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Televisions and Projectors
Media Servers and PCs
Expert
May 1, 2008 12:14 AM
updated: May 1, 2008 12:14 AM
This author is correct when he says that the capacitors on the converter or what some call the ballast circuit goes bad in these monitors. That is how I acquired a 22 inch wide screen monitor. They were told that the monitor would cost more to repair then the what a new one would cost. But not to me!. I replaced two capacitors and re soldered several bad solder connections due to the heat build up on certain parts. If you are handy, or have the electronic skills to resolder and replace capacitors AND can get the stubborn monitor apart, you may be able to repair what you thought was landfill. Now I do not encourage the unexperience3d person to open these monitors because the converters or what some call the ballast board can and will hurt you if you do not know what you are doing.
"Those who do not know their opponet's arguments, do not completely understand their own".
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