In a laptop, the inverter refers to a small circuit board housed as close to the monitor lamps as possible. An LCD typically requires two monitor lamps to illuminate your display, and those lamps require a higher voltage than the rest of your machine. The inverter powers these bulbs to increase the brightness of your display to a crisp, visible level.
When the inverter in a laptop goes bad, this can cause multiple problems with your machine. It can cause your screen to flicker on and off, become too faint to read, or even cause a faint buzzing noise. To test whether your inverter in your laptop has in fact gone bad, you will need to do one of two things: either replace the inverter board with one you know to be functional, or connect a backlight lamp you know to be functional. If the inverter board works or if the good backlight does not work, you know your original inverter board has gone bad. In most cases testing a good backlight will be easier, as most backlights are universal and will work as long as the connectors match those on your inverter board. To access either of these components, remove your screen bezel in accordance with your manufacturer’s instructions. Once removed, you will see the inverter board beneath your screen. The left side connects to the LCD cable, while the right connects to your backlight. Be sure when installing or removing any components of your machine that you have removed the AC adapter and battery from your machine to prevent shortage or electric shock.
Additionally, if you have a multi-meter you can attach it to the inverter cable connection on the motherboard itself to check that your inverter is receiving power. If you don’t, switching the inverter board or backlight will yield similar results. In some cases, your laptop will have a lid closed switch. If your model does have one, check to make sure that it is not sticking by tapping it repeatedly. If this changes the display of your monitor, your inverter may be fine; however that switch may be cutting off power to your display.
Laptop inverters are specific to each machine and not interchangeable. To replace your inverter, you will need to find the specific part number, which can usually be found in your user manual, or by contacting the manufacturer. For some companies, you can look up the information for your machine and its individual parts online as well. Inverters are generally easy to find at any laptop parts retailer.