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Mystery Dull Screen

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johnners    0

Hi all,

My first post. I hope this is in the right section.

 

I have a new (2nd hand) HP Elitebook 8440p. It has a very dim display. When I cycle through the 0%, 25%, 50 % etc. brightness setting, it makes little difference. It is brighter on 100% and dimmer on 0%, but the intermediate options do nothing.

 

I already have another 8440p and I can tell that the full brightness on this new one is closer to 50% on the old one.

 

I have tried the following:

 

Updated all the drivers

Uninstalled and reinstalled the drivers

Tried tweaking display settings as recommended online (although some of those settings don't appear on this laptop)

I have removed the screen from the good laptop and installed it on the new machine

I have switched all the display cables /connectors from the good latop to the new machine.

The older machine still works fine, with the hardware from the new machine, but I still have the same problem with a dull display on the new machine.

 

Also the dim screen seems to have a slightly blue / purple tinge to it.

 

Is there some other hardware or software option that I have missed? It's really baffling me!

 

Any advice would be appreciated as I am out of ideas and as I have bad eyesight, I'm unable to use this machine at the minute.

 

TIA

 

Johnners

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+jnelsoninjax    11,405

Most laptops have back-lights that are prone to die after many years of use, unless you are good at disassembling laptops, you might just consider getting a new machine, since you stated that you have poor eyesight, then I'm leaning towards you do not have the ability to disassemble it. Do you have the budget to replace the laptop? One other thing that just occurred to me: does this happen when on AC or the battery? If it happens on battery, you could try checking the power management settings for brightness. One other thing to try is to plug in an external display, that should circumvent the issue.

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goretsky    1,003

Hello,

 

As @jnelsoninjax noted, you are describing the classic symptoms of a failing CCFL inverter.  You can try swapping drives between the "bright" and the "dim" HP Elitebook 8440p's, just to verify it isn't some kind of problem with software, but you will likely need to replace that inverter and, possly, the fluorescent lamp. to get the screen working normally again.

 

Regards,

 

Aryeh Goretsky

 

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virtorio    3,025
Posted (edited)

It's almost certainly the backlight. I had an HP 8710p laptop long time ago (great laptop). By the time I replaced it, the display brightness made it pretty much unusable as a laptop.

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+DevTech    1,446

How on earth can it be the backlight when he has switched the LCD screen from one laptop to the other with ZERO change in symptoms?

 

You all know the backlight is an integral assembly with the LCD screen right?

 

8 hours ago, jnelsoninjax said:

then I'm leaning towards you do not have the ability to disassemble it.

He already switched BOTH screens and cables etc - sounds like ability there staring you in the face

 

2 hours ago, goretsky said:

You can try swapping drives between the "bright" and the "dim" HP Elitebook 8440p's

He already swapped the entire screen sub-system!

 

2 hours ago, virtorio said:

It's almost certainly the backlight.

Almost certainly NOT!

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virtorio    3,025
Posted (edited)
7 minutes ago, DevTech said:

Almost certainly NOT!

Almost certainly YES!!

Edit: Ok, I only read half the original post, so maybe not, but it could still be an issue with a hardware component that's not part of the display assembly. 

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+DevTech    1,446
8 hours ago, johnners said:

Hi all,

My first post. I hope this is in the right section.

 

I have a new (2nd hand) HP Elitebook 8440p. It has a very dim display. When I cycle through the 0%, 25%, 50 % etc. brightness setting, it makes little difference. It is brighter on 100% and dimmer on 0%, but the intermediate options do nothing.

 

I already have another 8440p and I can tell that the full brightness on this new one is closer to 50% on the old one.

 

I have tried the following:

 

Updated all the drivers

Uninstalled and reinstalled the drivers

Tried tweaking display settings as recommended online (although some of those settings don't appear on this laptop)

I have removed the screen from the good laptop and installed it on the new machine

I have switched all the display cables /connectors from the good latop to the new machine.

The older machine still works fine, with the hardware from the new machine, but I still have the same problem with a dull display on the new machine.

 

Also the dim screen seems to have a slightly blue / purple tinge to it.

 

Is there some other hardware or software option that I have missed? It's really baffling me!

 

Any advice would be appreciated as I am out of ideas and as I have bad eyesight, I'm unable to use this machine at the minute.

 

TIA

 

Johnners

Thanks for the very detailed description that no fault of yours was not actually read by anyone!

 

You have done some great diagnostic work to present us with a wonderful mystery!

 

In many laptops of that era, a very popular feature was a light detector that was used to automatically adjust screen brightness. You should check for that and disable it in settings or if it exists then shining bright light at the sensor should cause the screen to get brighter.

 

Otherwise the problem is on the motherboard area that sends the brightness level.

 

Since you inherited this laptop, also check the BIOS versions

 

 

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Daniel F.    559

If the screen has been ruled out the next place to look is the graphics card.

 

if its an IGP your out of luck as you would need to change the CPU and i doubt it would be worth it. 

 

If its a dedicated GPU you maybe able to swap out the card and try that.

 

You could swap over the parts from the other one?

 

And i just thought you have checked the gamma setting too right? 

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