Solved! HP Laptop Screen Dead?

[cmk45]

Hi all. I have a HP DV7-1451nr laptop with a screen that appears dead. This unit has an ATI Radeon GPU, so I don't think that it's the same issue that other models with the overheat/desolder NVidia GPU are having, plus my symptoms seem to be different. I never got any strange lines, colors, or anything else on the screen before the problem cropped up. Here are the current symptoms:

1. Screen is completely black, with no backlight, and I cannot see anything displayed on the screen if I shine a bright flashlight on it.
2. The external monitor HDMI port works perfectly if I connect it to my TV. In fact, that's how I'm typing this now.

Here's what lead to this point...

Intermittently for the last month or so, the screen would occasionally be dead upon startup or after hibernation. Usually it would come to life within a few minutes after I messed around with it (open/close screen, unplug, remove battery, hold down power button for 30 seconds, reboot). I suspect that getting it to work again was more related to my handling of the unit than anything else, as just the other day it was initially dead, and cycling the screen open/close three times brought it back to life. Now I can't get it to come back at all.

I'm guessing that I have either a bad screen, damaged wire, or bad connector somewhere? If so, what's the best way to go about diagnosing the issue? If I were to buy a replacement screen will it come with the associated cables/inverter/bulbs that may be damaged and will that likely solve the problem? I'm willing to do just that if I can just get this thing working again.

Since I can't see anything when I shine a flashlight on the screen, that indicates that it's not likely just a bulb issue, right?

I'm not a computer expert, but know my way around, and I'm confident that I can take apart/replace whatever needs done. I just need some help identifying the problem further.

I'm about to start some exploratory work to see if I can see anything that is damaged, but I'm afraid that the problem won't necessarily be visible.

Please let me know if there is other info that might help figure this out.

 

[frozenlead]

Generally the cables don't break on LCDs. From the sounds of it, your LCD has just died. Your inverter may be okay, but it's difficult to tell. You can plug a multimeter into your inverter and boot your PC to see if it outputs a good voltage.

Anyway, replacing an LCD is easy, though sometimes expensive. Generally the screens come without cables, but, like I said, they're rarely the issue.

 

[cmk45]

Thanks, that helps. I'll check the inverter output voltage when I pull apart the bezel. Any idea what voltage I should be getting?

Looks like a replacement lcd runs about $125 to $150. I'd be happy to spend that to get this thing working again.

 

[frozenlead]

It should be pretty high, actually, several hundred volts. Unless you really know what you're up to, you probably shouldn't. Here's two nice articles google gives:

http/www.fonerbooks.com/test.htm
http/www.fonerbooks.com/laptop14.htm

The general rule though is if your screen goes black with no output, and the output on your external screen is fine, your LCD is bad. If your display flickers or the backlight goes on and off, the inverter is bad.