HP Pavilion ZD8000 Video Problems

Posted on 2010-08-25
Medium Priority
Last Modified: 2013-11-17
On this laptop,  i just replaced the motherboard in this system and now the back light for the screen only works once the system has been on for awhile.  Was wanting some input on thoughts before i proceede.

I am thinking that the inverter may be going out or a wire that is loose.

Any Ideas will help and thanks ahead of time
Question by:david1986
LVL 24

Expert Comment

by:B H
ID: 33527491
i think your assessment is spot on - it's either a loose wire (less likely), a failing inverter, or a failing backlight bulb.

replacing the inverter should be about $15 and take you about 20 minutes.  checking for a loose wire maybe 20 minutes but if you replaced the motherboard, you know how to do this already just wiggle it.

replacing the bulb is significantly harder - the bulb costs about $30 but you have to take apart the display panel to a very low level, and be real careful that no stray hairs or dust make it in between the layers

there's not much troubleshooting you can do other than start replacing stuff

Author Comment

ID: 33527860
Thanks so much for your response.

In case I wasn't clear above:

When the system is FIRST turned on (after it's been off for awhile and is cool) the problem typically occurs. (Backlight doesn't work)

After a few minutes it seems to 'warm up' and starts working fine.

Does this point to a more specific hardware failure?

Thanks again for the help!
LVL 12

Expert Comment

ID: 33528199
Agree with bryon4403.

You must determine the problem is with the mother board or the LCD display?
A loose wire can be an issue, try moving your screen if it helps.

I would connect the laptop to an external monitor and see if you get the same problem.
If you get an immediate video on the external monitor  ---> it means the problem is with your LCD display.
Then you have to spend more time to check the inverter, backlight and for loose connectors.

How old is your machine?
I suspect a failing back light could give rise to the problem described.

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LVL 24

Accepted Solution

B H earned 1000 total points
ID: 33530156
well, you know those florescent tube lights some offices have... and how sometimes they take a few seconds to turn on... like they're warming up or something....

that can be caused by a failing bulb, but it can equally be caused by a failing inverter (or in an office that would be a failing ballast - both store power and give it to the bulb)

so it's really 50/50 inverter or bulb...  the thing that creates light in your display panel is a really tiny florescent tube bulb exactly the same as in an office ceiling, just a lot smaller

if you're going to take the time to replace the bulb, you may as well replace the inverter since it's so cheap and you have to take it out anyway to get to the bulb... or you could try just the inverter first since getting to the bulb is considerably harder

you can do both yourself for around $45 and 3-4 hours - or if you don't feel like doing the work there's services you can send it to that will do it for about $125 and 1-2 weeks, we like to use pelltechnology.com

it's really 50/50 and any troubleshooting that doesn't include swapping parts, will still keep it at 50/50 because the symptoms are the same between the inverter and bulb.

i'd put my money on the bulb being bad, but it's really 50/50
LVL 18

Expert Comment

ID: 33560567
One thing to note....is their any discoloration?  Sometimes on a failing CCFL they display is sometimes pinkish/reddish hue to it.  And when you watch it "warm up"....does it come on like it was on a dimmer switch and you are turning it from low power to high?
or does it just....blink ok I'm awake I'm awake!  and everything is from black to 100%?

As stated above, plug in an external monitor...and see what happens with it as well?
When running an external monitor, you may need to restart the machine with the monitor plugged in for the system to detect that an external has been plugged in....and also may need to hit special keys to make the screen work as well.  IE: FN (function button) and like F5 ....or a variation thereof.

Author Comment

ID: 33564499
I found a wire that had came out of one of the plugs.  Once I repaired that wire, the problem did not surface again.  Im going to give it a few more days of the customer using it and if all is well i will reward points.  

Once again, thanks for the advice.
LVL 24

Expert Comment

by:B H
ID: 33565966
wow that's awesome

gotta be careful when pulling that plug out of the motherboard, so many little wires :)

Author Closing Comment

ID: 33568545
Thanks for the help!!!!

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