No video on Laptop Disp until Windows Loads

Hewlett-packard Pavilion dv9500t noteboo...
January 21, 2010 at 07:12:03
Specs: Windows 7, Ultimate 64 Bit
This problem is relatively minor as of now, but I can see it causing problems if I needed to restore my system. I saw a similar post on the overclocking area, but I don't overclock so I'm posting here.

This problem started appearing on a consistent basis beginning at the end of December. Prior to that for a couple of weeks, the problem would only intermittently appear.

When the computer is turned on, the normal behavior is for the screen lamp to turn on first, followed by the POST screen, then the OS Load Screen.

The current behavior is that when the computer is turned on, the screen lamp does not turn on, there is no POST Screen or an OS Load Screen. The knee-jerk response may be a bad video card, but the screen lamp and video display once the Windows Login Screen appears. Additionally, if you do hook up an external monitor (either VGA or S-Video) the video output is on that screen. There is no change in behavior on the LCD Screen, regardless of what's hooked up to it.

I've been using PCs for over 12 years, and repairing hardware/software issues proficiently for about four, and I've got to say this one has me positively stumped. My PC is out of warranty, so the only support from HP I'm getting is the instant Chat support... which sucks. I swear the people working those systems are high school kids who don't have any knowledge of troubleshooting... all they do is follow the script.

Thanks for staying with me so far. I'd like to provide the detailed troubleshooting information that may help.

- I did take the entire machine apart to make another repair (noisy fan - it was not removed, it needed machine oil. Runs very quiet now.) The problem was appearing before that, but hey, every bit of information is important.

- I have flashed and updated the BIOS to the latest version (F.59A Dec 2008)

- I have updated the video card drivers (at the insistence of the HP 'support' people.) Smart people know that Windows Drivers for the display aren't loaded until, oh, I don't know until WINDOWS is loaded. The fact that the screen loads when Windows is finished loading shows me that the drivers are working correctly. But, I digress.

- I have attached an external monitor (Both S-Video and XVGA) and the proper output is displayed there. Still no change on the LCD Display.

- Tried various key combinations during POST, including FN+F4, F10, etc. No dice.

- Through the external monitor, in the BIOS interface, I have 'reloaded the setup defaults.'

I have literally tried everything short of a system disassemble and using a multimeter to examine individual diodes and circuits on the MB (and I would never do that, because a repair simply wouldn't be worth it.) I don't know what to do.

I'm really hoping that someone will be able to shed some light on the situation, because it could be problematic... what if I needed to boot from a CD, or enter Safe Mode, etc. when I didn't have access to an external monitor, like if I'm at a business meeting and my computer decides not to boot. It's not like I can say, "hey does anybody have a spare monitor, my computer is kind of picky."

At present, I'm thinking this is a motherboard issue.... because with laptops problems like this are always the motherboard. Hopefully some Electrical Engineer majors or anyone with extra insight can simply provide me with the answer to this question: Is this a benign problem that won't really hurt anything, or, is this a sign of further failures of the system. I fear that it's the latter.

If you'd be able to solve the problem completely, I'd be very grateful. Thanks for sticking with me and for providing your assistance.

Best wishes,
Patrick V.
(Purdue University, West Lafayette IN)

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January 21, 2010 at 07:37:12
"I've been using PCs for over 12 years"

Your computers Lamp is only made to last for about 7 years. Might want to get it repaired or consider upgrading. Is the screen bright once Windows loads or very dim?

How old is this laptop?

Never mind I looked the Laptop up and it is fairly new. If it is still under the 1 year part warrantee I would call HP. They are usually good at RMAing defective parts.

"My PC is out of warranty"

Dang, then consider finding one on E-Bay that is available for parts. I do this when ever I break a screen because the cost of these parts are almost as much as a new laptop.

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January 21, 2010 at 11:49:09
This following might ease your befuddlement on the symptoms displayed. Video adapters and monitors have two modes that they run in.
Alphanumeric mode: This is the mode used by the Bios.
Graphics mode: When Windows starts up, it switches to this mode.

It appears that the alphanumeric mode is not working in either the video adapter or the monitor.

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January 21, 2010 at 14:06:38
Thanks everyone for the replies so far!

@ace-omega: I do not believe that the screen is 'broken' because once Windows loads, the screen operates as good as it did when it was new. Interesting idea about a parts laptop. It's kind of like a "parts car" isn't it...

@aegis: That is an interesting thought about the graphics/text modes on the monitor. If that's what it is, let's thank God that it's not the graphics end that is misbehaving. With regards to that, though, both the HP Splash Screen during POST and the Windows Load screen are graphical. The HP Splash Screen displayed at the native resolution, showing the HP Logo as well as the Phoenix BIOS logo. The Windows 7 Load Screen is a high resolution animation, as well. Do you have any other thoughts?

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January 22, 2010 at 10:52:50
patrickvogt, It might 'appear' that the bios is using graphics mode, but there are ways to display simple graphic displays in alphanumeric mode.

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January 22, 2010 at 19:55:57
Here's an interesting new development.

I removed the graphics driver so that it would revert to the default VGA driver. The LCD Screen went dead and would not come back on. I plugged in the S-Video TV Cable.

Here's something that I noticed earlier that I didn't think to include. When the computer is starting and connected to the S-Video, there is a thin white border around the output. When the GUI would load (and the Graphics Driver was started) the white border would disappear.

When I uninstalled the graphics driver, the following happened:

1) LCD Screen went dead and would not turn on.
2) White border went through to display during the GUI.

... making me wonder:
Does the motherboard have some sort of low level display adapter that is active during startup and its output for the LCD is a little screwed up? I'm wondering this because, without the proper display driver to load, this 'failsafe' adapter would continue to operate.

Let me know if this is on, or crazily off the mark.

Thanks again!

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