The screen inverter failure is very similar to the backlight lamp failure. In both cases the screen gets very dark and the image on the screen becomes very faint, barely visible under a bright light. If you suspect the inverter board failure, I know only one reliable way to test that. It’s either replacing the inverter board with a known good one and see if it works, or connecting a known good backlight lamp and see if your presumably bad inverter lights it up.
In most cases I go with the second method – testing the laptop with a known good backlight lamp. Why? Because backlight lamps are pretty much universal. The same backlight lamp will work with many different inverters as long as they have matching connectors. I’ll talk about these connectors later.
The inverter board is located inside the Dell Inspiron E1505 display panel under the Gateway NX560XL LCD Screen. In most laptops you can access the inverter board if you remove the LCD screen bezel. The inverter board has connectors on both ends. The left side of the inverter is connected to the LCD cable. The right side of the inverter is connected to the backlight lamp which is mounted inside the LCD screen. Check out this display diagram.
Gateway NX560XL LCD Screen(Resolution: 1280x800 pixels;Aspect ratio: WXGA, Wide screen )
LP089WS1 (TL)(A1) LCD Panel(Size: 8.9 inchs;Resolution: 1024*600 pixels)
HP PAVILION DV5 SERIES 15.4 WXGA LAPTOP LCD Screen(Size: 15.4 inchs Resolution: 1280*800 pixels)
To make sure that inverter board is getting power from the motherboard (via the LCD cable), you can test it with a multimeter. In my case I connected the “+” lead of the multimeter to the pin 1 on the connector and the “-” lead to the ground trace around the screw hole. I got about 19.4V DC on that side of the inverter, so it’s getting power from the motherboard.
WARNING! If you accidentally short something on the inverter while testing it, you can damage the inverter or even the motherboard. Proceed on your own risk! Not sure? Don’t do that!So, the inverter is getting power from the motherboard, but the Gateway NX560XL LCD Screen is still dark. Apparently, it’s either bad inverter or failed backlight. Let’s test it with a known good backlight.
There are two different types of backlight connectors, you can see them on the picture below. The top one (big) is not as common as the bottom one (small). I do most of my test with a backligth lamp which has a small connector.
DELL VOSTRO 1700 17 WUXGA LCD SCREEN glossy(Size: 17.0 inchs
Resolution: 1920x1200 pixels)
Apple PowerBook G4 Aluminum A1085 17 LCD SCREEN WXGA+(Size: 17.0 inchs
Resolution: 1440x900 pixels )
Acer Aspire 5920 Series 15.4 WXGA LCD SCREEN(Size: 15.4 inchs
Resolution: 1280x800 pixels )
Here’s what I’m going to do:
1. I will unplug the Gateway NX560XL LCD Screen from the right side of the inverter. Basically, I’m unplugging the LCD backligth lamp which is located inside the screen.
2. I will plug in my known good backlight lamp which you can see on the picture below. Please notice that my test backlight lamp is shorter than the screen, but for the test purpose that’s OK.
Finally, when you ready to test the laptop, unplug the LCD screen from the right side of the inverter.Plug in your test backlight lamp and turn on the laptop.In my case, the backlight lamp lights up, so the inverter board works properly.
COMPAQ PRESARIO CQ50-139WM 15.4"" WXGA LCD Screen(Size: 15.4 inchs
Resolution: 1280x800 pixels )
COMPAQ PRESARIO CQ50-130US LAPTOP LCD SCREEN 15.4 inch(Size: 15.4 inch Resolution: 1280x800 pixels )
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