Laptop backlight quitting intermittently

  • Thread starter Thread starter DaveC
  • Start date Start date
D

DaveC

Averatec laptop backlight turns off after random lengths of time. Can still
see the dim images on the screen that behave normally to mouse inputs, so the
LCD is still alive.

I presume that the high-voltage PCB that runs the bulb is going bad. Is there
any chance that this is a virus or software bug that is causing the backlight
to turn off?

I Googled for this but nothing definitive came up.

Thanks,
 
DaveC said:
I presume that the high-voltage PCB that runs the bulb is going bad. Is there
any chance that this is a virus or software bug that is causing the backlight
to turn off?
Click to expand...

Not really. But it need not be the inverter at fault, it could easily
be a cabling issue. What model Averatec is this?
 
Thus spake (e-mail address removed):
Not really. But it need not be the inverter at fault, it could easily
be a cabling issue. What model Averatec is this?
Click to expand...

Model: 3200
Tilting the screen hinges back and forth does not start or stop the
phenomenon.

Thanks,
 
Thus spake (e-mail address removed):
Not really. But it need not be the inverter at fault, it could easily
be a cabling issue. What model Averatec is this?
Click to expand...

Is the inverter circuit on the motherboard or is it on a separate PCB?

Thanks,
 
More likely the CCFL tubes themselves, they are like a flouresecent
tube without the heater electrodes at the ends. A sign is the they
either start to flicker and the 'whites' become tinted in the
picture.

But the dc-dc inverter that steps the 12V supply up to around 1,800V
(1.8KV) could also be the cause but I'd go for the tubes first.

Have a peep here -: How to replace the backlight
http://www.dnd.utwente.nl/~grit/backlight/ccft.html Clicking the link
will open it in a new window.

Davy
 
More likely the CCFL tubes themselves, they are like a flouresecent
tube without the heater electrodes at the ends. A sign is the they
either start to flicker and the 'whites' become tinted in the
picture.

But the dc-dc inverter that steps the 12V supply up to around 1,800V
(1.8KV) could also be the cause but I'd go for the tubes first.

Have a peep here -: How to replace the backlight
http://www.dnd.utwente.nl/~grit/backlight/ccft.html Clicking the link
will open it in a new window.

Davy
Click to expand...


Yes the CCFL tubes can fail, but they won't generally
exhibit the symptom the OP described if/when they do, to
work when turned on then fail outright, but then work again
later.
 
I was having an issue with a new LCD and inverter. The backlight still
wasnt functioning. Then someone told me about the "toggle switch" that
turns the backlight on or off when the lid is opened and closed. Supposed to
be near the keyboard. Maybe it has a short or isn't functioning.
=======================================
 
DaveC said:
Averatec laptop backlight turns off after random lengths of time. Can still
see the dim images on the screen that behave normally to mouse inputs, so the
LCD is still alive.

I presume that the high-voltage PCB that runs the bulb is going bad. Is there
any chance that this is a virus or software bug that is causing the backlight
to turn off?

I Googled for this but nothing definitive came up.

Thanks,
Click to expand...

Loose connection / bad joint somewhere. Prodding about with an
insulated tool should narrow it down.

NT
 
Thus spake shockwa:
I was having an issue with a new LCD and inverter. The backlight still
wasnt functioning. Then someone told me about the "toggle switch" that
turns the backlight on or off when the lid is opened and closed. Supposed to
be near the keyboard. Maybe it has a short or isn't functioning.
Click to expand...

What model is your laptop?

Thanks,
 
DaveC said:
Is the inverter circuit on the motherboard or is it on a separate PCB?
Click to expand...

The inverter is always on a separate PCB in the upper half of the
laptop, because the HV wires need to be as short as possible (they
radiate EM noise, and they're also lossy).

Apart from the backlight switch issue mentioned by another poster, you
might have a heat issue on the inverter. I'd open up the screen half of
the laptop and let it run until it fails, then _carefully_ squirt
freeze spray on the inverter to locate the bad component.
 
DaveC said:
Thus spake shockwa:


What model is your laptop?

Thanks,
--
DaveC
(e-mail address removed)
This is an invalid return address
Please reply in the news group
=====================================
Click to expand...

It's a Fujitsu Lifebook S6210. Now my problem is I can't seem to find the
lid close(pin)switch. I've looked everywhere near the hinges, keyboard,
inverter, etc. Well thats my luck. See if you can find it with this pic I
took. http://home.pacbell.net/shockwa/images/laptop.jpg
 
shockwa said:
It's a Fujitsu Lifebook S6210. Now my problem is I can't seem to find the
lid close(pin)switch. I've looked everywhere near the hinges, keyboard,
inverter, etc.
Click to expand...

What makes you think it has one? Some laptops are magnetically
activated and there is no exposed switch.

Ian Singer


--


=========================================================================
See my homepage at http://www.iansinger.com
hosted on http://www.1and1.com/?k_id=10623894
All genealogy is stored in TMG from http://www.whollygenes.com
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I am near Toronto Canada, can I tell where you are from your reply?
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Ian Singer said:
What makes you think it has one? Some laptops are magnetically activated
and there is no exposed switch.
Ian Singer
Click to expand...
=========================================>
ok well I guess I wasn't specific enough. Where is the lid close magnetic
thingie? or
could it somehow be stuck in the close position because of removing the LCD.
I was aware it could be a magnetic switch, but where is
it on this model or one similar?
 
shockwa said:
ok well I guess I wasn't specific enough. Where is the lid close magnetic
thingie? or
could it somehow be stuck in the close position because of removing the LCD.
I was aware it could be a magnetic switch, but where is
it on this model or one similar?
Click to expand...

Cant tell you. You would need a parts manual. On a Toshiba its just to
the right of the left hinge and you can activate it with the lid upen by
moving a magnet acoss the lid on the ouside (side opposide screen).

Ian Singer

--


=========================================================================
See my homepage at http://www.iansinger.com
hosted on http://www.1and1.com/?k_id=10623894
All genealogy is stored in TMG from http://www.whollygenes.com
Charts and searching using TNG from http://www.tngsitebuilding.com
I am near Toronto Canada, can I tell where you are from your reply?
=========================================================================
 
Ian Singer said:
Cant tell you. You would need a parts manual. On a Toshiba its just to the
right of the left hinge and you can activate it with the lid upen by
moving a magnet acoss the lid on the ouside (side opposide screen).

Ian Singer

--


=========================================================================
See my homepage at http://www.iansinger.com
hosted on http://www.1and1.com/?k_id=10623894
All genealogy is stored in TMG from http://www.whollygenes.com
Charts and searching using TNG from http://www.tngsitebuilding.com
I am near Toronto Canada, can I tell where you are from your reply?
============================================
Click to expand...
I guess I could always ask Fujitsu support what type of switch it is either
a pin or magnetic and where it might be located.. Wonder if they disclose
that type of information?
 
hello.

guess the only prob. on your pc is the connection of the ballast
to bulb,
try to check if it is properly suitted, and if not well guess that
its time for you to change the bulb or your backlight,

that's it.

good kuck
 
Found this post after google-ing for Averatec LCD issues. I have the
same problem as the Original Poster. After anywhere from 10 seconds to
an hour or more of use, the backlight (I am guessing) will die out. You
can faintly still see an image on the screen. Did anyone find out if it
was the backlight, or inverter, or a heat issue?

I am about to just remove the whole LCD screen upper half and turn this
into a home only mini PC using an external monitor...

Thanks in advance for any tips.
Click to expand...


It's typically a CCFl driver board problem.
 
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