Dim Lapdog screen

I have an elderly NEC lapdog, when I switch it on the display is very
dim and I have to increase the brightness to get it to a useable
level, is just what happens to screens when they get on a bit, or is
there something that can be done?
It's not worth spending much (any) money on it as the battery is on
it's last legs, but if I can get a bit more life out of it that would
be good.

 

Speedgazebo MOTP #1 spoke:

is the clue - many laptops automagically dim the screen to conserve
battery.

--
Rob_P
UKRM(at)indqualtec.co.uk
uppercase(d) BBIWYMC#1 BOG#11? MRO#31 IBCDBBB#1(kotl)
FJ1200, CCM130 Benelli Cabriolet (gone)
Looks like Rab C Nesbit.

 

which can be over-ridden in the power management settings

 

It does it when it's turned on when it's plugged in, so I wouldn't
have thought that applies. It's been getting dimmer over the past few
months.

 

It is.

 

I'm assuming the screen is still dim when running off the mains adapter?

My guess is the high voltage inverter module for the backlight is on its
last legs. I had an older Toshiba Satellite model that this happened to,
a brand new module was surprisingly cheap on ebay. Replacement involved
removing the bezel surrounding the screen, unplugging the old module and
plugging in the new.

 

Is the sort of thing I wanted to hear.

 

it's fucked then

 

Mind out if you take it apart while still powered up, as it can give you
quite a belt.

DAMHIK

 

It is.


Being "elderly" its probably safe to assume LCD screen - the light is
produced by a long thin (about 2 or 3mm dia) florescent tube.

The relacement tube will be more than the laptops worth + ditto for anyone
to fit the thing.

If you can liberate a tube the right length from a scrapper you might get
away with it, but the connector probably won't be the same - lots of fun
insulating a join in silicone insulated wire against 600V at high frequency.

Sometimes they use self-adhesive reflective foil to hold the tube in place,
good chance of wrecking the display assembly getting the old tube out.

 

About 600V (1200V before the tube strikes) IIRC - and thar be capacitors!
(althogh not very big one's).

But then if its doing that, it probably isn't faulty.

 

Is what I didn't really want to hear, but is what I suspected would be
the answer.

 

Or a little Labrador.

 

It would have to be very little. I wouldn't want a Labrador on my lap
- not for very long anyway!

 

You say you have to increase the brightness - this sounds like it's a
software thing (i.e. power management not doing what it's told) rather
than dying hardware.

If the problem is a dying inverter or backlight, it may intermittently
work fine but at the times when it doesn't want to work, there's
nothing you can do to adjust the brightness back up again. And in my
experience, that doesn't usually result in it going less bright than
you'd like - it goes so dim that you need to be sitting under a bright
light to see that there is anything other than uniform blackness on
the screen.

David.