HDX inverter/backlight failure

[HaggisCat]

Here's a used one and it comes with the inverter.

 http://www.ebay.com/itm/HP-HDX18t-X18-Laptop-OEM-LCD-Video-Cable-Inverter-498324-001-DD0UT7LC002-/11...

 To note though, used stuff can fail too simply because it is used and you don't know how many miles are on it.

 Just from your last comment, it now sounds like the inverter is going, sorry for the confusion. 

 Here is some information that may help you understand about how it works :

 An inverter is just like the "Ballast" that you find in fluorescent lighting set up and the fluorescent tubes are pretty much the same as the lamps in the HDX screen.

 They laptop can have the same symptoms as the fluorescent lamps, eg flickering, dimming when they get old, shutting down for hours and then suddenly working again.

 The inverter steps up the voltage to fire the lamps and when it fails it can become intermittent, working for a few minutes/hours and then it will suddenly stop.

 If that inverter is new for 30 dollars I would go for that and start there.

 Another scenario is that the inverter is fine and the lamps are going, there is no way of knowing until you replace the inverter. There are kits to replace the lamps, but the screen is not meant to be taken apart and is easily damaged. For the most part I recommend replacing the screen if this is the case.

 I did replace the lamps myself to see if it could be done and it was difficult, the lamps are thin and very fragile. On top of that, the wires that came with the lamps were too thick to replace in the channels so I had to resolder the old wires on the new lamps.

 But we will not go there right now.

[HaggisCat]

Here's the part number for that cable. 498288-001

 I had a look around at my sources and they are rare, I would buy the one on ebay just for the sake of having a spare, if you don't want it, I may snatch it up.

[acxel22]

thanks again for the input, I'll get that kit, sounds like a good deal for inverter+cable, gonna risk the used one, see if it helps, and then I can try the cable as well if no luck.

I'll give an update when I get this in a week or two, until then, I hope the screen keeps working, so far as long as laptop is running, there is very few flickering and screen seems to hold on.

[acxel22]

well I received cable+inverter, the inverter has no part # on it, and it`s green. same size, but does'nt work at all, no image whatsoever with it.
The monitor cable works, but still same issue. Weird since in the auction the picture showed a different inverter, will complain to the seller but now I need to buy another inverter...

[HaggisCat]

That really sucks that it doesn't, contact the seller and see what he has to say. The green one he sent you is from original stock, and off course pulled from a used machine but that doesn't mean to say it's faulty.

 The blue one in the photo may be an updated version of the original or at least that is what I have come across. So far the new ones that I've ordered have always been blue and are made by Toshiba.

 It's also very possible that the backlights themselves have failed.

 At this point see of the seller will send you another inverter and if it still doesn't work, you can assume it's the backlights and the screen will have to be replaced.

  There are lights for sale on e-bay and it is possible to replace them, but it's very difficult and not for every one.

[gobarman]

Hello

My HP Dv8 display when off a month ago, I turned on my computer and then when the log in screen show the display went off. Lucky enough because I was using my computer with an external monitor and my default option for closing the lid was set to do nothing I was able to close the lid and the main image came to my monitor so I was able to use the computer. I ordered a replacement inverter with the part number from the HP maintenance manual to inverter-shop.com I didn’t realize that they are based in China and took forever; when it arrived it was the wrong part. The LCD connectors fit but the display connector has more pins. So I pull out the inverter, assembled my computer back and order the part (with the same part number) from a site in the US. Meanwhile I kept using my computer with the monitor.

The inverter arrived today and it is the right one, I prompted to place it in my computer and at first is seem a success, the HP logo came on the screen all the way until windows started then, the screen went off again. Now If I close and open the lid the image come back for a short time but then it goes off again, sometimes in 3 seconds, sometimes in 30.

I proceeded to replace the new inverter with the old defective and this is having the same behavior, but before it didn’t even lit the screen. So either the new one is defective as well or is something else.

I thought it could be the magnetic switch of the lid on the power button board so I start to play with a magnet around it and when the magnet pass around it turns on again, so I assumed that this was the defective piece. But just to check I tried turning on the computer and then unplugged the module. So the computer started and after a few seconds it went off again so I doubt this is the problem.

Any thoughts?

-Is not a configuration problem because screen goes off in windows, safe mode or in the bios screen.

-Is not the LCD because when is on the image is crystal clear and bright.

-Video card? Is possible that the video card is defective? But I have no problems when using an external monitor in the VGA or HDMI connections?

- Two faulty inverters? Why does the old one suddenly started working after I pull it out and back again?

-The cable maybe? Maybe it has gone bad because I was using the laptop with a tv to watch movies and the lid was closed to avoid the glare next to the TV and the temperature of the computer could fried the cables? I tried shaking the cables while the computer is on but this does nothing, only unplugging and plugging back

-Worst case it maybe that motherboard is defective and the power to the LCD drops after a few seconds.

Thanks for your help!

[HaggisCat]

Thanks for all the thorough trouble shooting, it points directly to the back-lights.

 You can either replace the entire screen or replace the back-lights.

 Post again with any questions, I am sure will have some.

If you still suspect a worn cable then moving the screen back and forth will affect the screen image. The cable wears around the hinge area.

[gobarman]

I guess the only way to completely be sure of that is connecting a new screen to the inverter?

What if i connect my dm3 screen to one of the dv8 inverter outlets (if the connections are the same)? The screen should turn on and stay like that if the bulbs are the problem? What if it behaves the same?

I’m just thinking that the DV8 have two bulbs and is it possible that both are gone badly at the same time? Should one be bad and then the screen be darker or off in one section? The LCD has some circuitry as well but does this control the bulbs? Or is this done entirely by the motherboard trough the inverter?

Is just that I live in the Caribbean and everything takes forever to get here plus is expensive and I don’t want to send the computer with a technician because must of them start with a system reinstall which will take me forever to reinstall to the point where I have it now.

Thanks

[HaggisCat]

The LCD circuitry doesn not control the bulbs.

 I would not advise you use the inverter from the dv8 on the dm3. The high voltage out-put on the dv8 inverter will damage (burn out) the dm3 lamps.

 One lamp in the dv8 could be bad or both, but the proper functioning of them depend on both being healthy.

 The lamps are both located at the bottom of the screen, the screen may appear darker and lighter in some areas because they are like florescent tubes, they can become dim in some areas and brighter in others.

 The inverter and the lamps are like a ballast and florescent tube arrangement you find in a hardware store.

 When both the inverter (ballast) and lamps become old, the lamps will flicker, work some days and not others.

The inverter puts out around 500 to 700 volts to fire the lamps and make them glow and when the inverter becomes old the voltage drops and the lamps simply stop producing light.

 When the lamps fail the filaments at each end become week and no matter how much voltage is applied, the lamps will not glow. Just like a florescent lamp it develops this black purplish ring around the ends of the tubes.

 When you come across a dual florescent light arrangement in a store and one lamp is failing, the other one suffers as well even though it may be healthy. This is true for you dv8, it's very unlikely that the mother board is the problem. The inverter is fed a low voltage and stepped up to fire the lamps.

 It's a tough call because you are so far away, is there not a local repair shop near by, if you send it into HP they will simply replace the entire screen assembly. This will take care of the problem, but it will be expensive, but you will get a new screen, cable, inverter and even the web cam will be replaced.

 I am not sure how to advise you. I don't' like telling you to go and get a new screen and have it be something else, but from all the trouble shooting steps you have given me, it sounds like the lamps are gone.

 I am just some guy in Canada that has rebuilt a number of HDX and dv8 machines, so it would be best to always get a second opinion before going out and purchasing a new screen.

[gobarman]

You are right I don’t want to risk the health of my working DM3 screen, but what I can do is trying to get a damaged screen from the local computer shop, just to check before going into the screen replacement. Although it makes sense that are the bulbs what are broken.

In your expertise how hard is to replace the bulbs vs. replacing the whole screen in case of the dv8? I have read in the process of changing the bulbs the screen is likely to get damaged plus for what I’ve briefly researched the cost of the bulbs is about $50 times 2 mean $100 unless you know where I can get them cheaper. In the other hand the cost of a new display is between $90 and $150. I’m worry about this since I’d a phone screen replace once with and OEM part and the quality was very poor compared to the original. Does anybody can recommend a supplier of a quality display?

For the display do I need any additional thing to replace it? Like double sided acrylic tape? I may replace my cables as well as they are a little worn around the hinges, the cable is around $50 so I’m looking to $150-$200 for this option.

Finally and doing a cost benefit exercise, unless somebody can recommend a supplier for the bulbs that will get the cost below $70,  then replacing the screen makes more sense. But since I’m worry about the quality of the display replacement and the cables adds another $50 bucks to the equation and if I can’t get this cost under $200 with a quality display replacement I may consider get the whole screen assembly replaced. I just found a supplier that sales this for $285 with the added benefit that my computer will look like new,  even that I take good care of it the plastic on the screen starts to show the shape of the keyboard on it, the cover only have minor scratches but the paint in luminescent HP logo has chip out.

So if anyone has some input and reference suppliers I’ll appreciate the info.

Thanks