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Clean the screen. Fire up the laptop and get it to boot. Darken theSo 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?
What do you mean by dimming? Dim? Dark? off?On Thu, 5 Jul 2012 22:35:42 -0700 (PDT), spamtrap1888
spamtrap1888@gmail.com> 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?
Clean the screen. Fire up the laptop and get it to boot. Darken the
room. Use a flashlight at an angle to see if you can detect any text
on the screen. For Windoze, you should see the Windoze logo as it
boots. If you do see an image, your LCD panel is probably fine, and
you are having a problem with the LCD inverter or the CCFL lamps in
the panel.
It's also a good idea to plug an external monitor into the VGA port to
see if the video card is working.
Determining if it's the inverter or the CCFL lamp is a bit tricky. If
you get a pink colored dim background, it's probably the CCFL lamps.
These are a major project to replace. You'll find instructions on web
sites selling LCD panels and CCFL lamps.
The way to be sure is to open the display section and attach a test
CCFL lamp to the inverter.
http://www.insidemylaptop.com/remove-replace-lcd-screen-ibm-thinkpad-t43p-laptop/
The LCD inverter is in the display section of the laptop. You only
need to go to Step #9. The hard part is splitting the LCD frame.
Don't use a metal screwdriver to pry open the display.
www.ebay.com/sch/i.html?_sacat=0&_nkw=thinkpad+t43+lcd+inverter
I usually buy two to avoid surprises. Note that there are different
part numbers for different display types. You'll probably have to get
the number off your inverter to be sure which is the correct number.
Bug me if stuck.
I suspect it is my CCFL lamp, because I still have an image, and itOn Thu, 5 Jul 2012 22:35:42 -0700 (PDT), spamtrap1888
spamtrap1...@gmail.com> 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?
Clean the screen. Fire up the laptop and get it to boot. Darken the
room. Use a flashlight at an angle to see if you can detect any text
on the screen. For Windoze, you should see the Windoze logo as it
boots. If you do see an image, your LCD panel is probably fine, and
you are having a problem with the LCD inverter or the CCFL lamps in
the panel.
It's also a good idea to plug an external monitor into the VGA port to
see if the video card is working.
Determining if it's the inverter or the CCFL lamp is a bit tricky. If
you get a pink colored dim background, it's probably the CCFL lamps.
These are a major project to replace. You'll find instructions on web
sites selling LCD panels and CCFL lamps.
Thanks so much for your help.The way to be sure is to open the display section and attach a test
CCFL lamp to the inverter.
http://www.insidemylaptop.com/remove-replace-lcd-screen-ibm-thinkpad-...
The LCD inverter is in the display section of the laptop. You only
need to go to Step #9. The hard part is splitting the LCD frame.
Don't use a metal screwdriver to pry open the display.
www.ebay.com/sch/i.html?_sacat=0&_nkw=thinkpad+t43+lcd+inverter
I usually buy two to avoid surprises. Note that there are different
part numbers for different display types. You'll probably have to get
the number off your inverter to be sure which is the correct number.
When the CCFL bulbs crap out, the display initially becomes pinkWhat do you mean by dimming? Dim? Dark? off?
Good idea.Another way to check the inverter is to waive an oscilloscope
probe around the area of the inverter. If it's running, you
can often see the radiation from it on the scope. That won't prove
the inverter board is good, but might lead you to check the lamp
before buying an inverter.
Bah. I use two 10:1 probes setup for differential input. My probesDon't go probing the inverter circuit unless you know what you're
doing. There's voltages there that the scope won't like at all.
You might find yourself with a dead laptop and a dead scope.
Great idea. I have an HP 4917A and never thought to use it to checkMost people don't have 'em, but an ultrasonic leak detector translates
ultrasonics down to the audible range. You can easily hear the inverter
transformer "singing" and hear it change as you adjust the brightness
setting.
I have an inverter used by gamers to light up the inside of theirI'm interested in hearing how to check CCFL lamps.
In the old days, you could plug on just about any inverter and see if
it lights. Today, the proliferation of connectors and inverter
topologies makes this harder.
Don't do it. Chances are good that you're going to apply HV to someI bought a fluorescent lamp checker at a garage sale.
It's basically a transmitter. You waive the antenna around
the lamp and see if it lights. Works great on household fluorescents.
I've been afraid to try it on a laptop for fear that it'd blow up
the display drivers.
I saw that on a Thinkpad T22 or T23. If you short something in theI don't have that model, but I did have a thinkpad with a bad fuse.
Was located near the display connector and well disguised. Didn't look
like a SMT fuse at all. Was open and extinguished the backlight.
Don't assume it's the CCFL quite yet. It's best to verify that theI suspect it is my CCFL lamp, because I still have an image, and it
has a rosy glow.
I just wrecked a Toshiba panel so I may not be the best person to ask.I haven't found a good page explaining how to
replace the CCFL, though. Are they fairly generic, or do I need to
make sure I have an OEM replacement? And can you suggest a good set of
replacement instructions?
What's your time worth? About $100 will get you a new display withThe inside-my-laptop site seems to recommend replacing the whole
display even if just the CCFL is faulty. Is replacing the CCFL that
much of a nightmare? My display is actually pretty good, so if I could
just replace the CCFL, I would, rather than take a chance of getting a
crap LCD.
I suspect it is my CCFL lamp, because I still have an image, and itOn Thu, 5 Jul 2012 22:35:42 -0700 (PDT), spamtrap1888
spamtrap1...@gmail.com> 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?
Clean the screen. Fire up the laptop and get it to boot. Darken the
room. Use a flashlight at an angle to see if you can detect any text
on the screen. For Windoze, you should see the Windoze logo as it
boots. If you do see an image, your LCD panel is probably fine, and
you are having a problem with the LCD inverter or the CCFL lamps in
the panel.
It's also a good idea to plug an external monitor into the VGA port to
see if the video card is working.
Determining if it's the inverter or the CCFL lamp is a bit tricky. If
you get a pink colored dim background, it's probably the CCFL lamps.
These are a major project to replace. You'll find instructions on web
sites selling LCD panels and CCFL lamps.
Thanks so much for your help.The way to be sure is to open the display section and attach a test
CCFL lamp to the inverter.
http://www.insidemylaptop.com/remove-replace-lcd-screen-ibm-thinkpad-...
The LCD inverter is in the display section of the laptop. You only
need to go to Step #9. The hard part is splitting the LCD frame.
Don't use a metal screwdriver to pry open the display.
www.ebay.com/sch/i.html?_sacat=0&_nkw=thinkpad+t43+lcd+inverter
I usually buy two to avoid surprises. Note that there are different
part numbers for different display types. You'll probably have to get
the number off your inverter to be sure which is the correct number.
Dim. Going but not gone.On 7/5/2012 10:54 PM, Jeff Liebermann wrote:
On Thu, 5 Jul 2012 22:35:42 -0700 (PDT), spamtrap1888
spamtrap1...@gmail.com> 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?
Clean the screen. Fire up the laptop and get it to boot. Darken the
room. Use a flashlight at an angle to see if you can detect any text
on the screen. For Windoze, you should see the Windoze logo as it
boots. If you do see an image, your LCD panel is probably fine, and
you are having a problem with the LCD inverter or the CCFL lamps in
the panel.
It's also a good idea to plug an external monitor into the VGA port to
see if the video card is working.
Determining if it's the inverter or the CCFL lamp is a bit tricky. If
you get a pink colored dim background, it's probably the CCFL lamps.
These are a major project to replace. You'll find instructions on web
sites selling LCD panels and CCFL lamps.
The way to be sure is to open the display section and attach a test
CCFL lamp to the inverter.
http://www.insidemylaptop.com/remove-replace-lcd-screen-ibm-thinkpad-....
The LCD inverter is in the display section of the laptop. You only
need to go to Step #9. The hard part is splitting the LCD frame.
Don't use a metal screwdriver to pry open the display.
www.ebay.com/sch/i.html?_sacat=0&_nkw=thinkpad+t43+lcd+inverter
I usually buy two to avoid surprises. Note that there are different
part numbers for different display types. You'll probably have to get
the number off your inverter to be sure which is the correct number.
Bug me if stuck.
What do you mean by dimming? Dim? Dark? off?
Backlight is still working somewhat. A lot of good tips, thanks.Another way to check the inverter is to waive an oscilloscope
probe around the area of the inverter. If it's running, you
can often see the radiation from it on the scope.
Most people don't have 'em, but an ultrasonic leak detector translates
ultrasonics down to the audible range. You can easily hear the inverter
transformer "singing" and hear it change as you adjust the brightness
setting.
I'm interested in hearing how to check CCFL lamps.
In the old days, you could plug on just about any inverter and see if
it lights. Today, the proliferation of connectors and inverter
topologies makes this harder.
I bought a fluorescent lamp checker at a garage sale.
It's basically a transmitter. You waive the antenna around
the lamp and see if it lights.
I don't have that model, but I did have a thinkpad with a bad fuse.
Was located near the display connector and well disguised. Didn't look
like a SMT fuse at all. Was open and extinguished the backlight.
You've got better probes than most people. Probes are significantlyOn Fri, 06 Jul 2012 00:02:54 -0700, mike<spamme9@gmail.com> wrote:
Here's another article on the problem:
http://reviews.ebay.com/Diagnosing-laptop-backlight-problems?ugid=10000000005308726
What do you mean by dimming? Dim? Dark? off?
When the CCFL bulbs crap out, the display initially becomes pink
colored. As more air leaks in, the CCFL lamp becomes dimmer and
dimmer until it finally quits altogether. Some inverters have
protection circuits to detect CCFL faults and will turn off the
display after a few seconds. I forgot what the thinkpad inverters do.
Note that this is for CCFL backlighting, not LED backlighting.
Another way to check the inverter is to waive an oscilloscope
probe around the area of the inverter. If it's running, you
can often see the radiation from it on the scope. That won't prove
the inverter board is good, but might lead you to check the lamp
before buying an inverter.
Good idea.
Don't go probing the inverter circuit unless you know what you're
doing. There's voltages there that the scope won't like at all.
You might find yourself with a dead laptop and a dead scope.
Bah. I use two 10:1 probes setup for differential input. My probes
will handle 1000VDC so there's not going to be a problem with the
typical 500-700V peak output from the inverter. However, if you
forget and set the probe to 1:1, there's going to be an expensive
problem in the scope.
I got my hands on one once with a killer zoom, but didn't thinkMost people don't have 'em, but an ultrasonic leak detector translates
ultrasonics down to the audible range. You can easily hear the inverter
transformer "singing" and hear it change as you adjust the brightness
setting.
Great idea. I have an HP 4917A and never thought to use it to check
the inverter. Thanks.
I'm interested in hearing how to check CCFL lamps.
In the old days, you could plug on just about any inverter and see if
it lights. Today, the proliferation of connectors and inverter
topologies makes this harder.
I have an inverter used by gamers to light up the inside of their
tower cases glued to a board. I've ripped off connectors from dead
LCD inverters and built a connector octopus. I've only found 4
different HV connectors so it's not an ugly mess yet.
I bought a fluorescent lamp checker at a garage sale.
It's basically a transmitter. You waive the antenna around
the lamp and see if it lights. Works great on household fluorescents.
I've been afraid to try it on a laptop for fear that it'd blow up
the display drivers.
Don't do it. Chances are good that you're going to apply HV to some
place that won't appreciate the voltage. Incidentally, I have a
customer that keeps blowing up monitors, mice and keyboards. It's
obvious that it's his "negative ion generator" that's causing the
problem, but he insists on using it near the computah.
I don't have that model, but I did have a thinkpad with a bad fuse.
Was located near the display connector and well disguised. Didn't look
like a SMT fuse at all. Was open and extinguished the backlight.
I saw that on a Thinkpad T22 or T23. If you short something in the
external LCD connector, it blows the fuse, which also kills the LCD
display. The clue is that BOTH the internal LCD and external video
are dead. I found a rather vague article on the problem:
http://www.tomshardware.com/forum/65493-35-strange-thinkpad-video-problem
Finding the fuse was easy. There was an F(something) reference
designator silkscreened nearby.
Incidentally, I have several USB microscopes that are quite handy for
looking at SMT components that my rapidly fading eyesight can't see.
Got a recommendation for a cheap one of those?
You shoulda led with that statement.I suspect it is my CCFL lamp, because I still have an image, and it
has a rosy glow.
On 7/6/2012 8:02 AM, spamtrap1888 wrote:
I suspect it is my CCFL lamp, because I still have an image, and it
has a rosy glow.
You shoulda led with that statement.
That's common among IBM laptops.
Replacing a lamp is a crap shoot.
I've done some that had removable panels that gave
access to the lamp.
Others have it buried DEEP in the frame and you have
to completely disassemble the display.
Be very careful when you unfold the boards with the
display drivers. It's not difficult to turn a dim
display into one full of bright lines.
Don't mix up the order or direction
of all those plastic sheets that fall out.
Like most things, it's a LOT easier the second time
you do it.
I once replaced both the inverter and the tube on a Thinkpad, only toSo 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 don't know, but I can measure one after I'm back from myYou've got better probes than most people. Probes are significantly
derated at higher frequencies. What's the peak voltage out of the
inverter when the lamp is open?
Maybe. However, I figured that anyone that owns an oscilloscopeBottom line is that most people asking the question asked here
would be better off not probing the output of the inverter.
Same problems. I bought several different styles on eBay for aboutIncidentally, I have several USB microscopes that are quite handy for
looking at SMT components that my rapidly fading eyesight can't see.
Got a recommendation for a cheap one of those?
I got my hands on one once with a killer zoom, but didn't think
I'd use it. Wish I'd bought it.
I do have a dental camera with fiber optic light source. Looks like
a colonoscopy machine. Gets real close, but takes up way to much space
to justify infrequent use.
I just put a layer of cellulose wrap over the camera lens to keep theThe ideal solution would be a high resolution camera with autofocus
and zoom. Need to get it far enough away to make room for the
soldering iron under it.
Yeah, that was another problem. I did OK, but was still somewhatI still haven't mastered the coordination needed to look one direction
at a display and solder in another direction.
It is difficult to tell if the CFL tubes or the power supply is bad unlessSo 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?
It is difficult to tell if the CFL tubes or the power supply is bad unless you have the proper test equipment to determine this. Generally speaking, after the CFL tubes go weak, the power supply also has a lot of wear on it. When I used to change the CFL tubes I also changed the power supply at the same time. This gives better reliability.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?
one thing; there's usually a film cap between the two CFL filaments,thatOn Sat, 07 Jul 2012 02:46:02 -0700, mike <spamme9@gmail.com> wrote:
You've got better probes than most people. Probes are significantly
derated at higher frequencies. What's the peak voltage out of the
inverter when the lamp is open?
I don't know, but I can measure one after I'm back from my
mini-vacation. I don't like running the inverters without a load as
I'm afraid the xformer will arc over. So, I've never bothered to
measure it. Also, some inverters will shut down if they see an open
or a shorted load.
My probes are nothing special. I bought them on eBay from some random
Chinese source. I got tired of constantly fixing my collection of HP
and Tek probes. So, I bought 10 new probes and am slowly blowing them
up as I blunder forward. By using two of these probes with
differential inputs to the scope, I essentially double the maximum
voltage rating of the probes.
What I really should use is a 100:1 probe that can handle 1200VDC:
http://www.dealextreme.com/p/250mhz-oscilloscope-probe-max-1200v-35610
Bottom line is that most people asking the question asked here
would be better off not probing the output of the inverter.
Maybe. However, I figured that anyone that owns an oscilloscope
should know something about how to use it and about its limitations.
Incidentally, I have several USB microscopes that are quite handy for
looking at SMT components that my rapidly fading eyesight can't see.
Got a recommendation for a cheap one of those?
I got my hands on one once with a killer zoom, but didn't think
I'd use it. Wish I'd bought it.
I do have a dental camera with fiber optic light source. Looks like
a colonoscopy machine. Gets real close, but takes up way to much space
to justify infrequent use.
Same problems. I bought several different styles on eBay for about
$20/ea. Something like this one:
http://www.ebay.com/itm/221064301923
All are rather crudely built, fat, etc. No adjustable illumination.
Very crude mounting hardware. The software universally sucks, but
fortunately there are substitutes. A major problem was that the
required drivers all interfere with each other, with my microscope
camera, and with my other USB video cameras. I don't know what to
recommend because nothing works perfectly.
The original plan was to strap the camera on the back of my hand to
aid in soldering. I'm getting old and my eyes are deteriorating. I
have trouble seeing SMT parts and thought the camera will help. It
does, but due to the lack of depth of field, the ability to keep the
camera in focus is limited. I've switched to surgeons eyeglasses,
which are much better.
The ideal solution would be a high resolution camera with autofocus
and zoom. Need to get it far enough away to make room for the
soldering iron under it.
I just put a layer of cellulose wrap over the camera lens to keep the
flux fumes from trashing the lens. Doesn't affect the image very
much, but does keep the lens clear. 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 still haven't mastered the coordination needed to look one direction
at a display and solder in another direction.
Yeah, that was another problem. I did OK, but was still somewhat
clumsy. The surgeons glasses were much easier.
Nope. There are no hot filaments on CCFL tubes. That's why they'reone thing; there's usually a film cap between the two CFL filaments,that
with the tube OFF,has a relatively low reactance compared to the unlit
tube,and allows the filaments to conduct the voltage and heat up,and after
the tube strikes it's arc,the arc shorts around the cap and the filaments
turn off.
If that cap shorts,the tube will never strike an arc,and the filaments stay
lit.
Probably a good idea especially if the LCD inverter is cheap. In theOn Sunday, July 8, 2012 6:45:08 AM UTC-7, Jerry G. wrote:
On Friday, July 6, 2012 1:35:42 AM UTC-4, 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?
It is difficult to tell if the CFL tubes or the power supply is bad unless
you have the proper test equipment to determine this. Generally
speaking, after the CFL tubes go weak, the power supply also has a lot
of wear on it. When I used to change the CFL tubes I also changed the
power supply at the same time. This gives better reliability.
Jeff L: How necessary is this?
Was the symptom no video at all?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.
Jeff L: How necessary is this?On Friday, July 6, 2012 1:35:42 AM UTC-4, 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?
It is difficult to tell if the CFL tubes or the power supply is bad unless you have the proper test equipment to determine this. Generally speaking, after the CFL tubes go weak, the power supply also has a lot of wear on it.. When I used to change the CFL tubes I also changed the power supply at the same time. This gives better reliability.