No backlight when on power

Yesterday my Pavilion zx5320us developed a problem that has been noted
in several posts in this from a couple of years back: if the laptop is
on the charger (ie plugged into mains power), the screen goes dark
after a minute or two. There is a very faint image still on the screen,
suggesting that the problem lies with the backlight. If I run the
laptop on the internal battery, there is no problem with the screen. I
tried HP's online chat for a solution and they suggested paying $295 to
send it back to HP. I can't really do that, even if I were willing to
do so, since we are in the UK for another seven months. Anyone have any
suggestions -- aside from running on battery power, shutting down for a
couple of hours for a recharge, and then rebooting?

TIA

Well, if the unit is ok on internal battery then it wouls suggest to
me that the backlights, infact the laptop itself is in good health.

But if on the power unit the backlight is dim or otherwise I really
would suggest trying a different charger for starters...!

Suppose the charger is putting a nasty 18Khz (appx) on the dc supply
this could cause all sorts of problems, batteries will continue to
charge with 'dirty DC' to some degree but the electronics would
suffer.

The backlight runs from an internal inverter that steps the 12V up to
around 1,800V for the CCFLs.

No doubt some sharks will tell you its the screen just to make a bit
of easy cash, so my advice would be to try the laptop on another
power unit first.

Davy

Thanks for the observations and suggestions.

It turns out that the unit is not okay on battery power after it's been
on for a while. After ten minutes or so the screen goes nearly black.
And then touching the sleep button very lightly will bring it back, but
only for 10 seconds or so. I borrowed an external monitor at a local PC
shop, plugged it in, and it works fine. They are willing to let me have
the monitor at a decent (for Scotland) price, so that's what I'll do
for the next seven months.

Davy wrote:
> Well, if the unit is ok on internal battery then it wouls suggest to
> me that the backlights, infact the laptop itself is in good health.
>
> But if on the power unit the backlight is dim or otherwise I really
> would suggest trying a different charger for starters...!
>
> Suppose the charger is putting a nasty 18Khz (appx) on the dc supply
> this could cause all sorts of problems, batteries will continue to
> charge with 'dirty DC' to some degree but the electronics would
> suffer.
>
> The backlight runs from an internal inverter that steps the 12V up to
> around 1,800V for the CCFLs.
>
> No doubt some sharks will tell you its the screen just to make a bit
> of easy cash, so my advice would be to try the laptop on another
> power unit first.
>
> Davy

You need to change the inverter and its a 10 minute job on these..
Circuit board under LCD screen under bezel on the lid assy.. Good
luck!

On a related topic, if the LCD develops white (or other possibly color) vertical
lines while otherwise displaying a clear bright image, would this be the cable
from the laptop to the LCD that has failed, or a recent defect in the LCD
itself? System displays perfectly on an external monitor. Thanks... Ben
Myers

On Wed, 03 Jan 2007 23:17:52 -0000, lid (ikenfixit) wrote:

>You need to change the inverter and its a 10 minute job on these..
>Circuit board under LCD screen under bezel on the lid assy.. Good
>luck!

ikenfixit wrote:
> You need to change the inverter and its a 10 minute job on these..
> Circuit board under LCD screen under bezel on the lid assy.. Good
> luck!

Thanks. It may be a ten minute job but the local computer shop (this is in
Scotland for now) wants about £150 (about $300 these days) to do it. I'm
over here for another 7-8 months and don't have any way of doing this
myself. I found a decent used LCD monitor at aother computer shop and am
using that until I get back to the States. This is the second major hardware
failure for this HP Pavilion laptop, the first being a hard drive crash
about 1.5 years into its life. Not impressive...

Ben meyers.. To answer your question.. If the lines are symmetrical in
nature its most likely the BGA ram causing an issue.. What chipset do
you have? If you have a lines and theyre not scattered even its most
likely the screen failing or the cable in some instances.. Talk soon
dude!
Ken

Solid vertical lines. The notebook is an IBM ThinkPad A20. I replaced the
defective screen with a smaller, but compatible one, buttoned up all the
hardware and now the system works perfectly... Ben Myers

On Wed, 10 Jan 2007 01:10:07 -0000, lid (ikenfixit) wrote:

>Ben meyers.. To answer your question.. If the lines are symmetrical in
>nature its most likely the BGA ram causing an issue.. What chipset do
>you have? If you have a lines and theyre not scattered even its most
>likely the screen failing or the cable in some instances.. Talk soon
>dude!
> Ken