Black screen ( backlight on ) , DV8t notebook

[feinverk]

Hi 

I own hp pavilion dv8t-1100 cto laptop and i'm having problem with my screen .. the laptop was working fine before i shut it down , opening it next time there was no display ( only lcd backlight ) .. i connected it to an external monitor and it works good , so i shut it down and started it again , began to close and open the screen and suddenly it worked ! .. i used the laptop the whole day and shut it down , next day the same problem happened no display but backlight is on .. so i repeated closing and opening it and it worked but that was the last time ... now i have no display at all , still only backlight and it's working fine on an external monitor ... there is no display from the beginning ( i cant even see HP logo ) 

Solutions i tried : 

- pressing fn+f4 and choosing duplicate or anything else , nothing just backlight on lcd no image
- removing battery and holding power button for 60 seconds , nothing
- exposing the screen to flashlight , it's not dim there is no display at all only backlight is on


is this faulty cable or inverter board or the lcd itself ? or it's just a loose cable ?  

could it be ram problem ? 


The problem happened suddenly , no falls or overheating issues .

Thanks in advance

 

[HaggisCat]

Hey there ! 

 I have a dv8 and a couple of HDX machines and I have become very familiar with them, so I am the right guy for the job.

 You have a good picture on the external monitor so your Mother Board and RAM are healthy. (not a RAM problem)

 Your screen is white so your inverter and backlights are good.

 Your video cable is faulty or the screen (pixel matrix) has failed. The internal wires in the video cable can wear around the hinge area and become disconnected, causing the problem you're having now.

 It's unlikely that the cable has become loose, but you can check this while you're in there.

 Start with the cable as it's the least expensive part, test the new cable while it's still disassembled, these machine are not easy to get apart. (I can help you with that)

 If you can't find any cheap parts for the dv8, you can order them for an HDX18 as they share the same parts when it comes to the screens and related parts.

 Your dv8 will have a resolution of 1920 x 1080 with duel CCFL lamps at the bottom of the screen. There will be a pair of wires coming out of the bottom of the screen. One pair for each lamp and they will be red & white and black & blue.

 If it comes to where you have to buy a new screen make sure the resolution is the same and that it has the correct number of wires. The HDX18 will be a Samsung screen and the dv8 will have one made by Chi-Mei. Both are made in China and are interchangeable. This isn't written in stone, but so far that is what HP have been putting in there.

 Before I can give some links on where to buy parts I need to know where you are from. I am guessing you're from the US as you have a cto model, is this correct ?

 Here are some videos for you to look at, HP Media Services Library and a one from me on how to fix the OSD pop up problem. Although you are not having this problem, my video goes into detail on how to get the speaker cover off and the bezel. Both of these things will have to be removed to gain access to the cable where it plugs into the Mother Board.

 If you need help getting to the videos in the HP Library, post again.

 http://h20574.www2.hp.com/default.htm?lang=en&cc=US&hpappid=psml  (make sure you're signed in before clicking on this link)

 http://www.youtube.com/user/HaggisCat1#p/a/u/1/8GreyKnF3TM  (when it gets to the part where I remove the keyboard, don't remove the keyboard, it's not necessary to remove it to gain access to the video cable on the MoBo)

 The entire screen assembly is still available from HP and the price isn't too bad (with exchange).

 

 The reason why you may want to exchange the entire assembly is because the screens are very difficult to remove. They are glued onto the screen bezel with this 3M industrial sided sticky tape. Some have worked a piece of dental floss in there to break the seal. The other problem you face is when mounting the new screen, it can be difficult do get every last little spec of dust and dirt out between the bezel and the screen.

 All this is assuming that the screen needs replacing.

Also note that you can only order this from HP if you're in the US.

 A new cable from HP is 42.24$, don't buy a used cable, you don't know how many miles are on it.

[feinverk]

First of all thanks for trying to help

actually my biggest problem is my country , i'm from Egypt , everything here is hard to get and very very expensive , so if i'm going to get something i think i'll order it online , which means more time and more money because of the shipping .

i disassembled it following the service guide and i found the display cable securely connected to the graphics card port , when i came to the lcd part i couldn't remove the backcover from the screen even after removing the front screws under the rubber covers , maybe i didn't give it a good try because it's my first time to do such a thing

i'll try to reach the inverter board again today and make sure the video cable is connected and not loose

Could it be a pixel matrix problem ? even when i close/open the screen it sometimes works ?

really i hope it's not a screen problem , because it will be very expensive for me and i think i'm going to buy a new laptop after sometime if it's not a cable problem.

regarding the OSD problem , i disconnected the ribbon cable as i'm working on an external screen , i checked your solution before but i think i'll keep the touch controls disconnected as i dont use them anyway

[HaggisCat]

Egypt !! WOW !!

 You're a long way from Canada.

 The fact that opening and closing the lid sometimes produces a picture would point to the cable.

 I have never come across a dead pixel matrix yet, so it probably is the cable, but there is no way of knowing for sure until it's replaced.

 The display back cover is difficult to get of. After the screws are removed it takes a fair amount of pressure in the right places (starting at the bottom edge) to begin releasing the snaps.

 The HP Library shows this best, but it makes the procedure look a little too easy. Can you get to the library and find your model ?

 Ounce the back cover is off, remount the screen and plug everything back in and boot up. Gently message the cable where it runs by the hinge and see if the picture fluctuates.

 Let me see if I can find a cable for you.

[feinverk]

i know it's a weird question but i'm going to ask it anyway

can i remove the back cover and reach the inverter without dismounting the whole screen from the laptop ? it takes more time and risk to dismount the whole screen

i reached the videos in the library and as a result i'm asking this question , why do i have to dismount the screen while i can remove the screws and back cover with screen closed ? but can i remove the inverter cover with screen mounted ?

you are the best one who can answer me here .. and really i'm very grateful and thankful for your help .

[HaggisCat]

There are these guys, and I have dealt with them before, and they are OK, but it's not new.

 http://www.pchub.com/uph/laptop/637-49234-14435/HP-HDX-X18-Series-LCD-Cable-18-.html

 It's inexpensive and free shipping though.

 And this, they ship world wide, but it's Fedex, so it probably would be expensive.

 http://www.notebookparts.com/products/description.php?II=55698

 Here's the part number of the cable,         496876-001

  You can Google this and many vendors will come up.

[HaggisCat]

If you want to access the inverter and the video cable you have to remove  the hinge cover. The cable that is plugged into the inverter are underneath the hinge cover.

 I order to remove the hinge cover you have to remove the screen from the laptop.

 To do that, follow the video(s) to disconnect the WiFi antennae cables, power cable USB board cable, etc.

 I am surprised that you were able to gain access to the four screws underneath the rubber covers while the screen is still on the laptop. I would have thought the case was in the way.

 You may be able to remove the back cover of the screen while it's still mounted on the bottom case, but I think you will have to remove it from bottom case to gain access to the inverter and eventually unplug the display cable from the inverter and the HP LED logo that lights up at the back of the screen.

 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 It's actually not that bad to remove the screen, take it one step at a time.

 Ounce the screen is off, it's so much easier to gain access to things then to try and skip steps.

 It's so much easier to remove the back cover with the screen off.

 Be careful not to drop the screen when trying to remove the cover, you may want to work on the floor with a rug underneath you. This may sound silly, but if you're holding the screen on your lap, it may slip out of your hands while trying to remove the cover.

[feinverk]

looks like my plan has failed .. okay i'm going to give it another try , probably tomorrow

Thanks for the cable links btw