Dell laptop LCD dark screen troubleshooting

[ggeoff]

Hi

I have managed to establish that my Dell laptop 6400 does not have a problem with generating display data. Connecting an external monitor provides a perfect picture. There is data going to the LCD screen but it is very dark. A web search suggests that I replace the inverter. I have done that but still have the problem. I have checked to see whether the new inverter was connected up properly and it is. I have run Dell Diagnostics and there is an error: "2000-0322 Error accessing the LCD inverter" On reflection, I should have run the diagnostics before buying a new inverter!

Whilst checking to see whether I had pushed the connecters to the new inverter fully home I managed to get the display working, but I lost it again. This suggests to me that the new inverter is working ok and maybe the old one was as well! I also checked the connections behind the LCD display, they are OK. So I am now thinking of what I need to do to check whether the power supply to the inverter is stable.

If my reasoning is correct what do I need to do to check the power supply to the inverter? But also, is there some other factor that clouds the issue?

[dee101g]

You could be having an invertor problem, but have you tried looking for the key that has a blue circle with an arrow pointing up and clicking it a couple times while holding down the Fn key? That's what mine needed when it gave the symptoms you are recounting.

[ggeoff]

Thanks dmcaarison,
"You could be having an invertor problem, but have you tried looking for the key that has a blue circle with an arrow pointing up and clicking it a couple times while holding down the Fn key? That's what mine needed when it gave the symptoms you are recounting."

Yes, I have used the screen brightness keys. I have seen though, that when the screen is dark, the brightness menu is missing. The Error message provided by Dell Diagnostics also refers to the inverter.

[ggeoff]

Hi

I have managed to establish that my Dell laptop 6400 does not have a problem with generating display data. Connecting an external monitor provides a perfect picture. There is data going to the LCD screen but it is very dark. A web search suggests that I replace the inverter. I have done that but still have the problem. I have checked to see whether the new inverter was connected up properly and it is. I have run Dell Diagnostics and there is an error: "2000-0322 Error accessing the LCD inverter" On reflection, I should have run the diagnostics before buying a new inverter!

Whilst checking to see whether I had pushed the connecters to the new inverter fully home I managed to get the display working, but I lost it again. This suggests to me that the new inverter is working ok and maybe the old one was as well! I also checked the connections behind the LCD display, they are OK. So I am now thinking of what I need to do to check whether the power supply to the inverter is stable.

If my reasoning is correct what do I need to do to check the power supply to the inverter? But also, is there some other factor that clouds the issue?

My reasoning is correct, the video cable plug had come disconnected. This was most likely to be caused because the cable is quite thick and could exert enough force to loosen the plug. I might also, which is quite likely, have moved the video cable when I replaced the inverter.

Incidentally, I couldn't manage to use my Fluke 110 multimeter to take a Hz measurement, as mentioned by Morris Rosenthal of Foner booksto, to check whether an inverter is working or not. If I can find out why, maybe my DMM is defective, I'll post back as that technique could be usefull for a lot of PC users, whether they are Dell owners of laptops or not.