[ltp] Re: My T22 backlight has died - how do I fix it?
Bert Haskins
linux-thinkpad@linux-thinkpad.org
Thu, 25 Aug 2005 14:18:46 -0400
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Wookey wrote:
>+++ Bert Haskins [05-08-25 10:49 -0400]:
>
>
>>Every Thinkpad ( 600x 770xy 390s, A2xx series, A3xx ) that I've ever
>>worked on has used a CCFL tube.
>>
>>
>
>OK, and a peruse of the web suggests that this is indeed the case for the T22.
>
>
>
>>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.
>>
>>
>
>
>
>>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.
>>
>>
>
>Right. I built a CCFL caving light a few years ago although the tubes were
>relatively short at about 12cm (4"). I can see that longer ones would be
>very delicate.
>
Amen!!
> Those tubes ran at about 250V - are the longer ones
>correspondingly higher voltage?
>
250V @ about 400CPS should light up the backlight.
I have never scoped the output even though I got quite a nice collection
of Tek scopes.
These things ( CCFL ) are strange!
As you bring up the voltage the tube will start to light in the center
and then spread to the ends.
If the inverter output leads are reversed, the lighting pattern will
change, sometimes quite a bit.
Strange, that output is AC!!!.
> I ask because I don't have spare inverter
>board so I'm going to have to use a meter/scope to guess if the inverter is
>working or not. Anyone know the voltage and frequency I should expect?
>
>If you still break them after fixing several then it must be tricky!
>
Again Amen!!
>
>
>
>>Typically the 'buy a new old one' could have its own set of problems.
>>
>>
>
>Indeed. The only reason to consider this option is that the case is broken,
>because the chassis is broken (near the back right hinge). And my battery is
>very tired and the replacement is dead. So I'm just wondering if I can be
>bothered fixing all these things or if it's time for a newer, faster, better
>laptop, especially as work will be paying :-)
>
>I'll give it a prod just to learn how to do it,
>
This can be a terrific ego trip if you manage to make it.
I really think that the repaired LCDs are even brighter than they were
when new.... better tubes?
That matters a lot to me cause I often take a laptop out on my salmon
boat where
the sunlight tends to wash out the display.
The "out on my salmon boat" thing is the main reason why I don't like to
have too much
money tied up in any given laptop.
A triple header can be rough on equipment.
In fact last year I had a close friend step right on the display of a
knocked over 390X while in the heat of the battle.
Needless to say it took a lot more than a CCFL to fix that one.
BTW he landed the fish.
>then decide. As both
>inverters and tubes are cheap I might as well.
>
>Wookey
>
>
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Wookey wrote:<br>
<blockquote type="cite" cite="mid20050825152005.GJ12986@xios">
<pre wrap="">+++ Bert Haskins [05-08-25 10:49 -0400]:
</pre>
<blockquote type="cite">
<pre wrap="">Every Thinkpad ( 600x 770xy 390s, A2xx series, A3xx ) that I've ever
worked on has used a CCFL tube.
</pre>
</blockquote>
<pre wrap=""><!---->
OK, and a peruse of the web suggests that this is indeed the case for the T22.
</pre>
<blockquote type="cite">
<pre wrap="">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.
</pre>
</blockquote>
<pre wrap=""><!---->
</pre>
<blockquote type="cite">
<pre wrap="">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.
</pre>
</blockquote>
<pre wrap=""><!---->
Right. I built a CCFL caving light a few years ago although the tubes were
relatively short at about 12cm (4"). I can see that longer ones would be
very delicate.</pre>
</blockquote>
Amen!!<br>
<blockquote type="cite" cite="mid20050825152005.GJ12986@xios">
<pre wrap=""> Those tubes ran at about 250V - are the longer ones
correspondingly higher voltage?</pre>
</blockquote>
250V @ about 400CPS should light up the backlight.<br>
I have never scoped the output even though I got quite a nice
collection of Tek scopes.<br>
These things ( CCFL ) are strange!<br>
As you bring up the voltage the tube will start to light in the center
and then spread to the ends.<br>
If the inverter output leads are reversed, the lighting pattern will
change, sometimes quite a bit.<br>
Strange, that output is AC!!!.<br>
<blockquote type="cite" cite="mid20050825152005.GJ12986@xios">
<pre wrap=""> I ask because I don't have spare inverter
board so I'm going to have to use a meter/scope to guess if the inverter is
working or not. Anyone know the voltage and frequency I should expect?
If you still break them after fixing several then it must be tricky!</pre>
</blockquote>
Again Amen!!<br>
<blockquote type="cite" cite="mid20050825152005.GJ12986@xios">
<pre wrap="">
</pre>
<blockquote type="cite">
<pre wrap="">Typically the 'buy a new old one' could have its own set of problems.
</pre>
</blockquote>
<pre wrap=""><!---->
Indeed. The only reason to consider this option is that the case is broken,
because the chassis is broken (near the back right hinge). And my battery is
very tired and the replacement is dead. So I'm just wondering if I can be
bothered fixing all these things or if it's time for a newer, faster, better
laptop, especially as work will be paying :-)
I'll give it a prod just to learn how to do it,</pre>
</blockquote>
This can be a terrific ego trip if you manage to make it.<br>
I really think that the repaired LCDs are even brighter than they were
when new.... better tubes?<br>
That matters a lot to me cause I often take a laptop out on my salmon
boat where<br>
the sunlight tends to wash out the display.<br>
The "out on my salmon boat" thing is the main reason why I don't like
to have too much<br>
money tied up in any given laptop.<br>
A triple header can be rough on equipment.<br>
<br>
In fact last year I had a close friend step right on the display of a
knocked over 390X while in the heat of the battle.<br>
Needless to say it took a lot more than a CCFL to fix that one.<br>
BTW he landed the fish. <br>
<blockquote type="cite" cite="mid20050825152005.GJ12986@xios">
<pre wrap="">then decide. As both
inverters and tubes are cheap I might as well.
Wookey
</pre>
</blockquote>
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