Most monitor or motherboard problems are caused by poor ventilation of the case. When the heat builds up over time it will cause parts called capacitors to blow out. Sometimes they fail quickly which shows up as a black display, no power at all or even just a flashing power light or flashing display screen. Other times they will slowly fail which is indicated by the monitor taking a long time to display a picture or a wavy picture until the unit heats up.
So what are capacitors? You can almost think of capacitors as very small storage cells, when you apply power they build up a charge and if the incoming voltage drops they will discharge and release the charge they are holding. This charge discharge allows the capacitors to help filter the power output from the power supply. The amount of charge they can hold and the discharge time are 2 things that determine the capacitor rating, these are measured in microfarads (uf). You can see in the diagram here that the capacitors are nothing more than 2 layers of aluminum foil and a paper insulator inserted into a metal can and soaked with a chemical called electrolyte. When the chemical overheats in the monitor it expands and causes the capacitor case to bulge and the aluminum layers to short out. Another way they can fail is if the top or bottom vent out and the chemical dries up. When this happens the capacitors fails to operate but looks fine visually.
What to look for on the power supply/inverter board: As discussed above the capacitors can fail in several different ways but usually will like something like these pictures.
Notice the bulging tops and even corrosion on some of them.
When repairing LCD monitors or other electronic assemblies is a very important to use the right parts or you will have to do the repair again soon or even worse it may damages the unit even more. Because of the high frequencies created in switching mode power supplies like found in LCD monitors and motherboards you need to use replacement capacitors that can take it without shorting out. You will also need to use Low ESR (equivalent series resistance) and also high temperature caps, the temperature marking will be 105c. The general purpose capacitors like you would find at Radio Shack will not work for LCD monitor repair. We recommend using Nichicon or United Chemicon capacitors, found in all of our repair kits.
When choosing replacement parts there are several things to check to get the correct part:
#1) Capacitance rating, measured in Micro Farads (220uf, 470uf, 820uf etc)
#2) Voltage rating (10v, 16v, 25v, etc) ( You can go higher on the voltage rating as long as it physically fits )
#3) Physical dimensions, measured in mm
#4) Needs to be LOW ESR ( Very Important ! ! )
#5) High ripple current
#6) High temp – 105c
Here are the capacitor series from several manufacturers you can use that have the correct ESR ratings:
Other important things to keep in mind when replacing capacitors is the polarity stripe on the side of the capacitor. When you insert the new part be careful and insert the new one with the stripe going the same direction as the old one came out. The stripe will be on the negative (-) terminal. Most boards will also have the negative side shaded and the positive (+) side marked with a + sign. If you put them in wrong they will blow out as soon as you apply power and could damage the circuit.
Be sure to look through our repair guide section, we may have a step by step guide for you model already posted. http://www.ccl-la.com/blog/index.php/category/monitor-repair/
If you need help repairing your unit you can ask questions and post pictures of the boards from your monitor or motherboard in our forums section here:
Our techs will be better able to assist you with the repair by looking at the pictures of the boards.
If you do not want to do the repair yourself we do offer a repair service. You can set up a service request by filling our the request form: http://www.ccl-la.com/blog/index.php/service-request-form/
We can repair most brands of LCD monitors and motherboards.