HP DV9000 display problem, not the usual one though

[shamrin]

Of course we all know about the GPU problems these awful HPs have but I have one here that has not caught that bug (yet). However, it does have a very strange problem that I just can't get my head around.

If you open the laptop and turn it on, the display never lights up, completely dark. But if you plug in an external monitor, the external monitor displays the BIOS screen and then proceeds to boot Vista just fine. However, if you just open the lid about 30 degrees and squeeze your hand in there to hit the power button, poof, the laptop display lights up with the BIOS screen. Now, if you immediately open the lid, as soon as Vista starts to boot, the screen will go dark again, never to return. If instead you leave the lid at 30 degrees until the desktop appears, then you are home free and can open up the lid all the way and everything is fine.

Because of the screen position issue I thought that we had a faulty magnetic lid switch, but unfortunately after changing that switch, there was no change in behavior. I suppose it could be a loose or shorted display cable, but that would be a lot more jittery and inconsistent that this. Once the display is on you can wiggle the lid all you want and it has no impact.

I would appreciate any ideas you have.

/sch

 

[FooseSB]

Of course we all know about the GPU problems these awful HPs have but I have one here that has not caught that bug (yet). However, it does have a very strange problem that I just can't get my head around.

If you open the laptop and turn it on, the display never lights up, completely dark. But if you plug in an external monitor, the external monitor displays the BIOS screen and then proceeds to boot Vista just fine. However, if you just open the lid about 30 degrees and squeeze your hand in there to hit the power button, poof, the laptop display lights up with the BIOS screen. Now, if you immediately open the lid, as soon as Vista starts to boot, the screen will go dark again, never to return. If instead you leave the lid at 30 degrees until the desktop appears, then you are home free and can open up the lid all the way and everything is fine.

Because of the screen position issue I thought that we had a faulty magnetic lid switch, but unfortunately after changing that switch, there was no change in behavior. I suppose it could be a loose or shorted display cable, but that would be a lot more jittery and inconsistent that this. Once the display is on you can wiggle the lid all you want and it has no impact.

I would appreciate any ideas you have.

/sch

I had this problem on mine, and replacing the display inverter solved the problem.

 

[shamrin]

Well, I've thought about the inverter but that doesn't quite go with the symptoms. If you start the computer with the lid open (and use the external display instead), you can go into device manager and see that Vista doesn't even recognise that there is an internal screen attached to the computer. A display with a bad inverter would still be present in the device manager and you should have data on the screen if you look closely. Neither of these being the case here, I can't see how the inverter could be the problem.

Are you saying that had these exact symptoms?

/sch

 

[MrUnknown]

It may be the cable going to the LCD. Might have a break in it

However, that doesn't explain why waiting until a specific point before opening the screen fully will work. Sure you aren't just hitting it lucky?

 

[shamrin]

It may be the cable going to the LCD. Might have a break in it

However, that doesn't explain why waiting until a specific point before opening the screen fully will work. Sure you aren't just hitting it lucky?

No, it's not just luck, I can get the LCD to work consistently by opening only 30 degrees. Incidentally, it's the position of the LCD in relation to the base unit, not just the position of the lid, in other words if I hold the thing at a funny angle so that the lid is open but still in the 30 degrees from horizontal position, it doesn't come on.

Again, if it's a loose cable, it should be loose not tricky.

 

[georgenoise]

Shamrin, did you ever find a solution to this? I'm having a very similar issue. If I take the LCD out of the bezel and rest it on the keyboard at any angle it will light up, boot all the way to the OS, reboot, turn off back on and I still get a good display. I can wiggle and jitter all the cables when it is out of the bezel or bracket that holds it in place and it works fine. Here is the strange part, if I take it out of the bezel and bracket, rest it on the keyboard and turn it on it lights up. If I put in back in the bracket or just resting in the bezel in the position it would normally be in it will stay lit until it has to go black to switch video modes or or until it is powered off and back on and then there is no display again. Take it back out and rest it on the keyboard and once again we have a display. I'm so confused and at a loss. I think it's a short somewhere but can't trace on down and I know it's not the inverter because I've already changed it out and the symptoms just aren't there for a bad inverter. Does anyone out there have a solution or should I just tell the customer their laptop is hosed unless they want to hook it up to an external monitor? Thanks guys.

 

[Larry Sabo]

Is it really black (as in no image) or is the lamp just off? I'm wondering if the lamp is finicky at firing up, just as you see some fluorescents in commercial buildings flicker as they are about to die. Does it do the same with another, compatible screen? I'm thinking pooled mercury within the lamp. Anyway, just a thought.

 

[usacvlr]

Sounds like just an lcd cable. I've seen this many times where it will work fine consistently at a certain angle.

Otherwise I would suspect a photosensor being used to detect light and dark to control the screen brightness in the presence of bright or dark/closed lid.

 

[maclaptech]

Sounds like cable/wiring to me...

 

[kwisher]

I had almost the same issue with a dv9700. Only the display presented bright green pixels. Would not do this on a external display. The condition was not present with the lid at 30 degrees from base. Replaced LCD and same issue. Getting ready to order new LCD/video cable. Will report back after I have this part replaced.

 

[Skyhooker]

Wow, I had EXACTLY the same problem with one a couple weeks ago. I was going to post about it, but haven't had a chance to really do in-depth work on it yet, as the owners took it on vacation and decided to deal with the quirky start-up problem until they got back. It's like there's just enough tension when the lid's open more than about 30 degrees to break a circuit, and that circuit only needs to be made long enough for something to initialize, but after that it isn't needed. It's one of the weirdest cases I've seen, and I'll be following this thread closely - please follow up if you find a solution. I don't think theirs was a dv9xxx series, though - can't remember offhand.

I did not see any image at all on the screen when it did not initialize, by the way, so I don't think it's just the backlight.

 

[usacvlr]

I see this often. The photosensor issue however is unique to macs. I don't think I've seen one on a pc.

 

[shamrin]

No luck yet

Sorry to have dropped out of the loop on this for a while. I'm still at a loss on this. I'm going to take the display off over the weekend and see if that give me any hints. It sounds like from some of the other remarks here like it could be a short in the data cable. Before I invest in another part, I would love to hear from someone who has tried a cable swap.

/sch

 

[georgenoise]

I'm taking a shot in the dark to say it's the cable. I have one ordered and will post once I have it installed. That's the only thing I can imagine it is as I've replaced the inverter, the screen is brand new and includes the bulbs. The only thing not ruled out was the cable, so for $8 plus shipping I will know soon. If that does not fix it I will have been defeated by a machine for the first time in a long time.

 

[shamrin]

I'm taking a shot in the dark to say it's the cable. I have one ordered and will post once I have it installed. That's the only thing I can imagine it is as I've replaced the inverter, the screen is brand new and includes the bulbs. The only thing not ruled out was the cable, so for $8 plus shipping I will know soon. If that does not fix it I will have been defeated by a machine for the first time in a long time.

Tell me about it. This is the second time I've taken on this white whale myself. I'm eager to hear your results.

 

[kwisher]

Happy to report that a new video cable solved the problem for me. HP sure had a bad design in the way they routed this cable right next to the left-side hinge, causing it to get pinched.

 

[shamrin]

Happy to report that a new video cable solved the problem for me. HP sure had a bad design in the way they routed this cable right next to the left-side hinge, causing it to get pinched.

Thanks for the update.

 

[kwisher]

I found it on eBay from a seller named "The Computer Store" for $45 and free shipping.