19 inch lcd tv set . I can see the picture in there very dark just like
the backlights are not working .
I took the screen apart and hooked up the lights and they were very
bright . So the lights and screen are working . Why wont it light up ?

Ken G. ha scritto:
19 inch lcd tv set . I can see the picture in there very dark just like
the backlights are not working .
I took the screen apart and hooked up the lights and they were very
bright . So the lights and screen are working . Why wont it light up ?

Inverter broken.
Slang

Read the whole post . I said the lights are working

On Fri, 19 Oct 2007 18:21:17 -0600, Ken G. wrote:

Read the whole post . I said the lights are working

Huh? Why should I re-read what post?

I think we all know somewhere that the lights _aren't_ working.

I decided to hold off commenting, because I felt ignorant. But since you
don't seem to be getting any useful answers, maybe I should throw in my two
cents...

If the light is working, but the image is extremely dark, that suggests
there's something seriously wrong with the driver circuitry. That would not
be a quick 'n easy fix.

If the lights are working and the display is dark, this is normaly a fault
with the panel driver, or part of the supply to the panel itself. This is
serviced with board substitution.

The main drivers for the panel are embedded in to the rear surface of the
display itself. This type of fix is to change the panel. The driver and
power supply board should be tried first.

--

JANA
_____


"Ken G." wrote in message
...
19 inch lcd tv set . I can see the picture in there very dark just like
the backlights are not working .
I took the screen apart and hooked up the lights and they were very
bright . So the lights and screen are working . Why wont it light up ?

From having repaired laptops with dark displays by replacing the inverter,
the inverter was always a small circuit card separate from the lights. I
don't know if LCD TV's are similar. But, if they are similar, then Slang
would seem to have a point in suggesting the inverter may be broken...the
inverter, not the lights.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working

"Fabian Fuller" wrote in message
et...
From having repaired laptops with dark displays by replacing the inverter,
the inverter was always a small circuit card separate from the lights. I
don't know if LCD TV's are similar. But, if they are similar, then Slang
would seem to have a point in suggesting the inverter may be broken...the
inverter, not the lights.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working



Having repaired a few thousand IBM Thinkpads over the last five or six
years, I agree that it is probably the inverter. On an IBM, and probably
many if not most other brands, it is a small narrow card mounted under the
LCD Panel. It is also relatively inexpensive.

Henry Mydlarz

"Fabian Fuller" writes:

From having repaired laptops with dark displays by replacing the inverter,
the inverter was always a small circuit card separate from the lights. I
don't know if LCD TV's are similar. But, if they are similar, then Slang
would seem to have a point in suggesting the inverter may be broken...the
inverter, not the lights.

I think by "lights are working", he means they light up from the inverter
in the normal manner but somehow the LCD panel is still very dark.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working

"Sam Goldwasser" wrote in message
...
"Fabian Fuller" writes:

From having repaired laptops with dark displays by replacing the
inverter,
the inverter was always a small circuit card separate from the lights. I
don't know if LCD TV's are similar. But, if they are similar, then Slang
would seem to have a point in suggesting the inverter may be broken...the
inverter, not the lights.

I think by "lights are working", he means they light up from the inverter
in the normal manner but somehow the LCD panel is still very dark.



Maybe the lights are lighting up but only dimly? We need more information.

Ok i didnt want to get to long winded .

First i have worked on around 40 or 50 LCD monitor/tv and little
portable DVD players and have seen many different problems . That said
The subject tv when turned on has a picture exactly like a monitor with
no backights , you can hardly see it at all .

I took the screen apart meaning i took the LCD glass panel off of the
frame and away from the backlights .
I hooked the now no LCD glass backlight frame up to the tv set and
turned it on and watched the tiny thin bulbs light up bright .. just
like any other i have tried this on .

I know what the inverter is , it`s working because the bulbs are very
bright . So bright it was hard on my eyes .
So ... the screen is showing a picture ( as above ) and the lights and
inverter are all working but the light is not shining through the LCD
glass screen .

Screen drivers were mentioned . I would guess this is the problem .

Are your brightness and contrast buttons working?
I had a sony TFT which had a burned transistor in the interface of the
control buttons causing no button pressing at all and in my case the
screen was on maximum brightness.
Replacing the transistor fixed the monitor.

Cheetah

"Sam Goldwasser" wrote in message
...
"Fabian Fuller" writes:

From having repaired laptops with dark displays by replacing the
inverter,
the inverter was always a small circuit card separate from the lights. I
don't know if LCD TV's are similar. But, if they are similar, then Slang
would seem to have a point in suggesting the inverter may be broken...the
inverter, not the lights.

I think by "lights are working", he means they light up from the inverter
in the normal manner but somehow the LCD panel is still very dark.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html


I was beginning to think it was just me. The OP did indeed say that the
lamps were alight and were "very bright".

That would certainly seem to rule out a problem with either the lamps, or
the inverter driving them. If there is a visible image - even though it is
of course very dark - from just the ambient room lighting, again as the OP
says there is in his first post, that would suggest that the panel drivers
are working. That makes it a bit of a mystery as to why the light from the
lamps is not correctly backlighting the panel to produce a 'normal' picture.
About the only thing that I can think of is that someone has had it apart
before, and assembled it somehow wrongly such that the light is being
blocked from getting into the lightguides behind the panel. The only other
possibility that I can think of is that there is a problem with the wiring
to the inverter, or a bad joint or crack on the inverter board, such that it
does not work and the lamps do not light, when it is all sandwiched back
together.

Arfa
Important: Anything sent to the email address in the message header above
is
ignored unless my full name AND either lasers or electronics is included
in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working

"CheetahHugger" wrote in message
...
Are your brightness and contrast buttons working?
I had a sony TFT which had a burned transistor in the interface of the
control buttons causing no button pressing at all and in my case the
screen was on maximum brightness.
Replacing the transistor fixed the monitor.

Cheetah

That's a good thought - I hadn't considered that it might in fact be stuck
at absolute minimum brightness. If you shine a light at the front of the
panel, and alter the contrast / brightness settings, can you perceive any
difference in the dark picture that is there ?

Arfa

hemyd wrote:
"Fabian Fuller" wrote in message
et...
From having repaired laptops with dark displays by replacing the inverter,
the inverter was always a small circuit card separate from the lights. I
don't know if LCD TV's are similar. But, if they are similar, then Slang
would seem to have a point in suggesting the inverter may be broken...the
inverter, not the lights.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working


Having repaired a few thousand IBM Thinkpads over the last five or six
years, I agree that it is probably the inverter. On an IBM, and probably
many if not most other brands, it is a small narrow card mounted under the
LCD Panel. It is also relatively inexpensive.

Henry Mydlarz



Well, I'd have appreciated 'some' sort of reply myself when I posted a
similar problem with a laptop [subject: Gateway M305 -- 10/18] this
week. I guess ya'll figured I had it in hand. I'm still waiting for my
eBayed inverter, and I leave town today....

Inverters 'can be' cheap. Cheaper than a new laptop, at least. But
they're expensive enough that it's worth shopping around. I found
inverters for this one ranging from the $20 'pull' I ordered, up to
almost $100.

On a laptop more than a couple years old, it would only be worth fixing
if one can find a deal....

jak

Sorry. I don't visit this newsgroup regularly, and I just didn't scroll
back far enough to see your post on the 18th. No intention of ignoring your
post...just didn't see it.

This thread got me to remember this one time when a laptop display would not
light up. It turned out to be a jammed plastic pin (like an on/off switch)
that normally got pushed down when the laptop was closed (thus opening the
circuit), and got released when the laptop was opened (thus closing the
circuit). Since it was jammed it never fully released to close the circuit.

Fabian

"jakdedert" wrote in message
...
hemyd wrote:
"Fabian Fuller" wrote in message
et...
From having repaired laptops with dark displays by replacing the
inverter, the inverter was always a small circuit card separate from the
lights. I don't know if LCD TV's are similar. But, if they are
similar, then Slang would seem to have a point in suggesting the
inverter may be broken...the inverter, not the lights.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working


Having repaired a few thousand IBM Thinkpads over the last five or six
years, I agree that it is probably the inverter. On an IBM, and probably
many if not most other brands, it is a small narrow card mounted under
the LCD Panel. It is also relatively inexpensive.

Henry Mydlarz
Well, I'd have appreciated 'some' sort of reply myself when I posted a
similar problem with a laptop [subject: Gateway M305 -- 10/18] this week.
I guess ya'll figured I had it in hand. I'm still waiting for my eBayed
inverter, and I leave town today....

Inverters 'can be' cheap. Cheaper than a new laptop, at least. But
they're expensive enough that it's worth shopping around. I found
inverters for this one ranging from the $20 'pull' I ordered, up to almost
$100.

On a laptop more than a couple years old, it would only be worth fixing if
one can find a deal....

jak

I am able to see the menues and did try the brightness settings . Its
hard to see anything but i did see the bright bar move .
I was the first one to take the screen apart
, their was some of that aluminum tape they like to use in these that
was never touched .
This screen uses 2 very thin bulbs , A set at top & bottom . The rest is
a real thick platic diffuser and a couple thin sheets of stuff in there
too .
The display assembly has enough of a hole at each end of the bulbs to
see them lit when everything is back together .
This set looked used .. finger prints & slight soilage . It has its
original box & all papers . It was a store return situation .

I was given another LCD tv set today , a Zenith 13`` with the exact same
symptom .. real dark screen . I found a blown fuse to the inverter and
fixed it right up .

You are quite correct, Fabian. I also repaired many laptops where the sleep
mode switch (operated by a lug near the pivot of the top cover) was jammed.
It makes the display go dark by shutting off the backlight.

Henry

"Fabian Fuller" wrote in message
et...
Sorry. I don't visit this newsgroup regularly, and I just didn't scroll
back far enough to see your post on the 18th. No intention of ignoring
your post...just didn't see it.

This thread got me to remember this one time when a laptop display would
not light up. It turned out to be a jammed plastic pin (like an on/off
switch) that normally got pushed down when the laptop was closed (thus
opening the circuit), and got released when the laptop was opened (thus
closing the circuit). Since it was jammed it never fully released to
close the circuit.

Fabian

"jakdedert" wrote in message
...
hemyd wrote:
"Fabian Fuller" wrote in message
et...
From having repaired laptops with dark displays by replacing the
inverter, the inverter was always a small circuit card separate from
the lights. I don't know if LCD TV's are similar. But, if they are
similar, then Slang would seem to have a point in suggesting the
inverter may be broken...the inverter, not the lights.

"Ken G." wrote in message
...
Read the whole post . I said the lights are working


Having repaired a few thousand IBM Thinkpads over the last five or six
years, I agree that it is probably the inverter. On an IBM, and probably
many if not most other brands, it is a small narrow card mounted under
the LCD Panel. It is also relatively inexpensive.

Henry Mydlarz
Well, I'd have appreciated 'some' sort of reply myself when I posted a
similar problem with a laptop [subject: Gateway M305 -- 10/18] this week.
I guess ya'll figured I had it in hand. I'm still waiting for my eBayed
inverter, and I leave town today....

Inverters 'can be' cheap. Cheaper than a new laptop, at least. But
they're expensive enough that it's worth shopping around. I found
inverters for this one ranging from the $20 'pull' I ordered, up to
almost $100.

On a laptop more than a couple years old, it would only be worth fixing
if one can find a deal....

jak