Bad Inverter Board Symptoms
If you turn your laptop on and see a distorted, dim or blank screen, don't immediately make plans to buy a new one. Instead, consider what components in the display could have malfunctioned. In the most likely case, you have a bad inverter board on your hands. The inverter board powers your laptop's LCD backlight by drawing direct current from the motherboard and converting it to alternating current, a much higher voltage. Without this increased voltage, your display cannot function. Learning to recognize the symptoms of a bad inverter board can prevent you from spending unnecessary money on repairs.
Carefully feel the portion of your laptop's LCD screen where the inverter board resides; usually, this is near the bottom. If you feel excessive heat coming from that area, the most likely cause is the inverter board not making a solid electrical connection with other components. The California Energy Commission website states that electrical resistance generates heat through friction of electrons. If the inverter board has a smaller area of contact than normal due to a loose connection, electrons from the current cluster together more closely and generate more friction; therefore, they generate more heat.
Dim or Blank Screen
If your screen goes dim, your inverter board may not be converting the voltage from the motherboard to a voltage strong enough to fully operate the backlight. The inverter board takes an input of 12 DCV, or direct current voltage. It should normally transform this into an ACV -- alternate current voltage -- in the hundreds. Without this voltage, electrical current cannot flow properly.
Diagnosing the Inverter Board
Because the inverter board and backlight are linked so closely, diagnosing problems caused solely by the inverter board can be difficult. Computer consultant Morris Rosenthal says in his ebook "The Laptop Repair Workbook" that the simplest method of diagnosing an inverter problem is to connect an external CRT -- cathode ray tube -- monitor to your laptop. If the display appears normally on a CRT, your laptop inverter is malfunctioning. You can also test inverter input with a multimeter.