Lenovo T43 Laptop Display dimming

[mike]

On 7/8/2012 9:41 AM, Jim Yanik wrote:
What I would really like is a

pseudo color far-IR camera, so I can see how hot things are getting
when I use my hot air SMT desoldering gun.

I'm not optimistic about that.

I have a crude far-IR camera used by firemen to find people
in smokey buildings. It's not calibrated, but I find that
the emissivity
of stuff varies so widely that it's useless for determining
relative temps.
If you aim a non-contact IR thermometer at a motorcycle
radiator, it reads reasonably accurately. Point it at the
aluminum cylinder and it's WAY, WAY off.

I cobbled together a crude setup for reflowing nVidia chips
on laptops. Gave up completely on IR and went with thermocouples
for temp measurement.

 

[Jeff Liebermann]

On Sun, 08 Jul 2012 12:17:17 -0700, mike <spamme9@gmail.com> wrote:

On 7/8/2012 9:41 AM, Jim Yanik wrote:
What I would really like is a
pseudo color far-IR camera, so I can see how hot things are getting
when I use my hot air SMT desoldering gun.

Ummm... watch your attributions. I wrote the above.

I'm not optimistic about that.
I have a crude far-IR camera used by firemen to find people
in smokey buildings. It's not calibrated, but I find that
the emissivity
of stuff varies so widely that it's useless for determining
relative temps.

True. All of them have a calibration knob, mostly to compensate for
changes in ambient temperature.

If you aim a non-contact IR thermometer at a motorcycle
radiator, it reads reasonably accurately. Point it at the
aluminum cylinder and it's WAY, WAY off.

Point it at a mirror and you get the temperature of whatever you see
in the mirror, not the temperature of the mirror. Yes, emissivity
matters.

I cobbled together a crude setup for reflowing nVidia chips
on laptops. Gave up completely on IR and went with thermocouples
for temp measurement.

Most of DVM's have thermocouple inputs. I got lucky and bought a
large box of pre-made thermocouples, in a variety of packages. I use
the tiny ones for spot temperatures. Still, it would be nice to have
a non-contact method that works.

In the past, I was working on converting a supermarket laser scanner
mechanism into a flying spot IR imager. I had something that sorta
worked but the response time was so slow, that is was nearly useless.
If I have time, I plan to continue as I now have a faster
microbolometer.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[mike]

On 7/8/2012 3:36 PM, Jeff Liebermann wrote:

On Sun, 08 Jul 2012 12:17:17 -0700, mike<spamme9@gmail.com> wrote:

On 7/8/2012 9:41 AM, Jim Yanik wrote:
What I would really like is a
pseudo color far-IR camera, so I can see how hot things are getting
when I use my hot air SMT desoldering gun.

Ummm... watch your attributions. I wrote the above.

I'm not optimistic about that.
I have a crude far-IR camera used by firemen to find people
in smokey buildings. It's not calibrated, but I find that
the emissivity
of stuff varies so widely that it's useless for determining
relative temps.

True. All of them have a calibration knob, mostly to compensate for
changes in ambient temperature.

The one's that I've seen have a calibration for emissivity.
Temperature compensation is internal and fixed.

If you aim a non-contact IR thermometer at a motorcycle
radiator, it reads reasonably accurately. Point it at the
aluminum cylinder and it's WAY, WAY off.

Point it at a mirror and you get the temperature of whatever you see
in the mirror, not the temperature of the mirror. Yes, emissivity
matters.

Depends on your definition of mirror.
If it's a front-surface mirror, yes.
IR doesn't go thru the glass very well.
I just did the experiment with a standard back-surface mirror
and a clear sheet of glass. Readings were similar and not anywhere
near the temp of the light bulb I was using as a a test source.

I cobbled together a crude setup for reflowing nVidia chips
on laptops. Gave up completely on IR and went with thermocouples
for temp measurement.

Most of DVM's have thermocouple inputs. I got lucky and bought a
large box of pre-made thermocouples, in a variety of packages. I use
the tiny ones for spot temperatures. Still, it would be nice to have
a non-contact method that works.

In the past, I was working on converting a supermarket laser scanner
mechanism into a flying spot IR imager. I had something that sorta
worked but the response time was so slow, that is was nearly useless.
If I have time, I plan to continue as I now have a faster
microbolometer.

 

[Sylvia Else]

On 9/07/2012 2:15 AM, spamtrap1888@gmail.com wrote:

On Saturday, July 7, 2012 3:53:32 AM UTC-7, Sylvia Else wrote:
On 6/07/2012 3:35 PM, spamtrap1888 wrote:
So how can I tell if it is the display, the backlight, or the
inverter?

And could someone give me an idea what's involved in replacing each?


I once replaced both the inverter and the tube on a Thinkpad, only to
discover that the actual problem was a break in one of the conductors of
the ribbon cable joining them.


Was the symptom no video at all?

Intermittently. When the video vanished, the image was just visible when
looked at from the correct angle. Although I didn't bother to prove it,
the broken conductor was presumably the one leading to the lamp. Breaks
in other conductors would have different effects.

Sylvia.

 

[Jeff Liebermann]

On Sun, 08 Jul 2012 18:21:20 -0700, mike <spamme9@gmail.com> wrote:

True. All of them have a calibration knob, mostly to compensate for
changes in ambient temperature.

The one's that I've seen have a calibration for emissivity.
Temperature compensation is internal and fixed.

Y're right. The antique design that I threw together didn't have AGC.
Range was determined by knobs and trim pots.

The FLIR imagers that I sometimes borrow has manual adjustments for
image temp range and emissivity as well automatic DDE (digital detail
enhancement) also known as AGC. On the side or bottom of the screen,
is a crude color to temp calibration strip.
<http://www.flir.com/cs/emea/en/view/?id=42844>
One of the product features is that it's almost point and shoot, with
all adjustments being automatic.

Point it at a mirror and you get the temperature of whatever you see
in the mirror, not the temperature of the mirror. Yes, emissivity
matters.

Depends on your definition of mirror.
If it's a front-surface mirror, yes.
IR doesn't go thru the glass very well.
I just did the experiment with a standard back-surface mirror
and a clear sheet of glass. Readings were similar and not anywhere
near the temp of the light bulb I was using as a a test source.

Try it with low-E window glass. It reflects IR from the surface
coating.
<http://www.wisegeek.com/what-is-low-e-glass.htm>

I just tried the mirror and light bulb test. Your correct. It
doesn't work. I do have a borosilicate glass SIR "hot mirror" that
reflects IR, but that's cheating. I tried it on the bathroom mirror
and it didn't reflect much heat. However, a polished piece of
aluminum sheet metal reflects IR just fine.

Zero for three. I'm not doing too well today.

Argh... the rubber grips on my Craftsman IR thermometer are oozing
oil, getting sticky, and slowly disintegrating. What else can go
wrong?

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558