[ltp] My T22 backlight has died - how do I fix it?

[Bert Haskins]

Wookey wrote:

>Over the last few months my backlight became more and more sluggish to turn
>on. recetly it went from 'up to 5 mins' to 'up to an hour', and now appears
>to have finally crokaed and hasn't come on in more than 10 hours of operation.
>
>I think it's knackered. So, does anyone know what type of backlight it is on
>these machines (CCFL, LED, something else),
>
Every Thinkpad ( 600x 770xy 390s, A2xx series, A3xx ) that I've ever 
worked on  has used a CCFL tube.
I have replaced quite a few of these with generally good results in fact 
on the last the owner was ready to
trash the whole box and was amazed that after the replacement he thought 
that it was brighter than most new laptops

I do check the inverter first though.
I use an inverter that I keep for just this purpose and if the screen 
does light up I debug the other circuits.
My test inverter runs on it's own power ( battery ) so it's not affected 
by other problems.

////// start rant /////
One thing that I don't like about the newer machines is that just about 
everything is built on the
motherboard including !@#$CUSS%$%& the DC/DC converter !@#$CUSS$%%%.
////// end rant ////////

I have found on one or two 390E/X boxes that the DC/DC converter was the 
whole problem.
It is a separate circuit board on these machines as it should!!!!!!  be 
on all machines

> and whether it is the
>tubes/whatever which tends to die or the inverter/controller which powers
>them. And where physically is the inverter and the actual light source?
>
>Any clues welcome. I am quite happy to take the thing to bits again and do
>reasonably hard-core replacement of bits
>
The CCFL tubes are VERY easy to break, imagine a #2 pencil lead that is 
12 or so inches long
and you will have to solder the leads on to this and manage to wiggle it 
back into the lcd assembly.

Even after doing this a few times, I still manage to break about one out 
of six and I always have at
least three before I start.
Replacement tubes are about ten dollars each.

> if I knew what was needed. Although
>it may be that 'buy a new old one' will be more cost-effective.
>
Typically the 'buy a new old one' could have its own set of problems.
You could gamble on a complete upper half and that would cover about
75% or better of the possible problems.

Good luck,
   Bert

>
>TIA
>
>Wookey
>  
>