How can i tell wether i need an led backlight replacement kit or a whole new led screen for my laptop?

Check for appropriate voltages going to the backlights from the PSU. If voltages are ok and still no backlights you may have to take the screen off and use a backlight tester to verify the individual strips integrity. This is tricky and you stand the risk of damaging the panel so be careful or get a professional to do it. If you are wondering why not purchase new backlights because everything else seems to be fine but the backlights are the only thing that's not functioning, that's because it is possible that the paper thin strip that connects all the individual backlight strips is shorting to the frame. We've had the same issue with this model and other brand/model that uses the same paper thin strip. We became aware that the strip was shorting to the frame by accident when we disassembled the screen an got to the backlights. We happened to be touching the connector strip and the metal frame and got a jolt and the backlights lit up momentarily when that happened. So we used a meter and verified there was a short. To rectify this situation (first verify that all your backlights are still good by using a backlight tester) then use a piece of electrical tape ( the length of the connector strip)and place the connector strip squarely an the tape providing extra insulation between the connector strip and the metal frame. If you don't have a backlight tester and you're just a do-it-yourselfer you can (since you are already at the connector strip) just proceed to use the electrical tape as described above and if you get backlights now then walla. You don't have to reassemble the screen to test if the backlights work. Just plug in TV and press the power button. The backlights will come on anyway. The pictures shows the connector strip placed on the black electrical tape.

i did this once, on very old CCFL monitor
and was very hard and weak brightness done
there are no dell schematics. from dell.
PCs have whole new screen upgrades LCD + LED all one one but is very expensive $100 (laptops common)
never seen any monitor upgrades sold, or kits.
the problem huge is not wiring, ever, it is the DIFFUSEr for CCFL is not any good for LED at all.
best bet if H3LL bent is google how , find others who have tried.
hacking.

Not a lot to go on here, Prabhdeep

Need the full model information

Example,
Acer Aspire 5535-5050

Post back in a Comment, or Reply; at end of this solution

Primer:

An LCD screen does not produce light,

http://solutions.3m.com/wps/portal/3M/en_US/NA_Optical/Systems/BehindTheScenes/Optics101/

Click on the monitor icon

Because of this the LCD screen needs an additional light source.
A Backlight is the additional light source.

A Backlight can be a CCFL, (Or more than one), or a series of LED's.
(Light Emitting Diode)

CCFL = Cold Cathode Fluorescent Lamp (Bulb)
Similar to Fluorescent lighting used in homes, and businesses; but on a MUCH smaller scale.
Average thickness is 2mm, or a little more than 1/16th of an Inch.
Or about the width of this capital letter -> O <-
Average length is almost as long, as the LCD screen is in height.

http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/

View the last 8 photos

(Do they break easily when trying to remove, and replace?
OH, YES!)

A screen Inverter is used to convert the power from the laptop, for the LCD screen, and Backlight.
If the laptop uses LED backlighting, it MAY or MAY NOT use a screen Inverter.
Generalized thinking (Can also be stated as 'Rule of Thumb'), is that if the laptop uses LED backlighting, it does NOT use a screen Inverter.

I also feel into this line of thinking, since none of the LED back-lit laptops seemed to use a screen Inverter; that came to the shop.
I have found this to be a fallacy from on here,......FixYa.....
I have looked up two laptops using LED backlighting, and discovered they also used a screen Inverter.

Now I post LED backlighting may, or may not use a screen Inverter.
Seems when LED backlighting first came out, a screen Inverter was used on some models.
Also seems as the LED backlighting technology progressed, no screen Inverter is used.

90 PERCENT of the time, the fault for bad Backlighting can be attributed to a bad screen Inverter.
Of course, this IS IF the laptop uses a screen Inverter.

For a laptop with LED backlighting that does not use a screen Inverter, and backlighting is bad (Dim, or non-existant), the next hardware part in the diagnoses to replace, is the LCD screen.

I now await the information I asked for above.
Then we can diagnose together.

Regards,
joecoolvette

OK Mel, it's your dime.

The LCD screen is bad. It may be just the Backlight, but since you purchased this baby new; it will have LED backlighting. There is NO replacing the backlighting, there is ONLY replace the LCD screen.

Primer if I may;

An LCD screen does not produce light.

http://solutions.3m.com/wps/portal/3M/en_US/NA_Optical/Systems/BehindTheScenes/Optics101/

(Click on the monitor image)

An LCD screen needs an additional light source.
A Backlight is the additional light source.

A Backlight can be a CCFL, (Or two of them), or a series of LED's.
(Light Emitting Diode)

A CCFL is a Cold Cathode Fluorescent Lamp. (Bulb)
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.

Average thickness is 2mm. That is a little larger than 1/16th of an Inch. (-> O <- approximate thickness)
Average length is almost as long, as the LCD screen is in height.

General example,

http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/

(View the last 8 photos)

Newer laptops like yours use a series of LED's.

A screen Inverter is used to convert the power (Electricity), from the laptop, for the LCD screen, and Backlight.

LED backlighting does NOT use a screen Inverter.

When an LCD screen that uses LED backlighting, has problems with the backlighting, the entire LCD screen is replaced as a unit.

Is the problem with the LCD screen itself? Could be. The entire LCD screen is replaced. Either way, replace LCD screen.

Now,....the above is just GENERIC information.
I need the laptop manufacturer name, and model number. The model number may be on the Palm Rest Cover, to the right of the Touchpad.
It WILL be on the bottom of the laptop.
Post back in a Comment.

This way I can see if there is a link to give you for a free Service Manual, and perhaps some pictorial information also.
Then I will guide you step by step, and we'll get that LCD screen replaced.

It isn't hard at all, I assure you. YOU CAN do it.

Regards, joecoolvette


(Psst, they don't have them anymore because it was a special sale.
Whoever the laptop manufacturer is, though; is obligated to repair it. Kinda hard to get them to replace the entire laptop. DOES happen though.

Laptop was like that from the factory. Is not the consumer's problem, is the factory.

I don't care if it came from Best Buy, Tigerdirect, Newegg, or your uncle; the FACTORY is obligated to repair it. DOES NOT matter if it was a Black Friday sale, Christmas sale, or an Easter Egg hunt.

DO understand about the time frame thing, though. Plus DO commend you for your willingness to repair. It is people like you that built the world, not sat by and watched)

Here are the eBay search results for your exact system model -

http://www.ebay.com/sch/i.html?_trksid=p5197.m570.l1313&_nkw=Toshiba+Satellite+L355D-S7809+screen&_sacat=0

1) Toshiba Satellite P300-13j LCD screen example,

http://www.screentekinc.com/Toshiba_Satellite_P300D-13J--17-inch--1440x900-wxgaplus-laptop-lcd-screen.shtml

Thin Film Transistor (TFT) Active Matrix LCD screen, that is WXGA, and uses one CCFL for a Backlight.

2) http://www.lcds4less.com/ToshibaLaptop__Toshiba_Satellite_P300D-12L__laptop-screens.html

Thin Film Transistor (TFT) Active Matrix LCD screen, that is WXGA, and has 1 CCFL for a Backlight.

There is a pretty good chance. The screen Inverter and LCD screen are a matched unit. I would remove the screen Inverter from the P300-12L, and use it also.

Looks like this,

http://www.lcd-inverter-shop.com/Toshiba/Toshiba-Satellite-P300D.html

If I may ask;
1) Is there obvious damage to the LCD screen?

2) If there is not obvious damage to the LCD screen, have you used an external VGA monitor with the laptop?

To see if the problem is the graphics chipset, or the video cable, or inside the Display Assembly.

A) http://www.irisvista.com/tech/laptops/Toshiba-Satellite-P305/take-apart-notebook-1.htm

B) http://www.irisvista.com/tech/laptops/Toshiba-Satellite-P105-P100/remove-lcd-screen-inverter-1.htm


Post back in a Comment.
Regards,
joecoolvette

[Primer:
An LCD screen cannot produce light by itself,
(Click on the monitor icon,

http://solutions.3m.com/wps/portal/3M/en_US/NA_Optical/Systems/BehindTheScenes/Optics101/ )

It needs an additional light source. A Backlight is the additional light source.
A Backlight can be a CCFL, (Or two of them), or a series of LED's.

LED stands for Light Emitting Diode

CCFL stands for Cold Cathode Fluorescent Lamp.
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale.

Average thickness is 2mm. That is a little larger than 1/16th of an Inch.
Average length is almost as long, as the LCD screen is in height.

http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/

Observe the last 8 photos especially. This article shows you that the LCD screen is an assembly. It is composed of layers. Just like the 3M company's tutorial. Also shows general instructions for replacing a Backlight.

A screen Inverter is used to convert the power from the laptop, for the LCD screen, and Backlight.
It is a small circuit board, and is usually mounted towards the bottom of the LCD screen, and behind the Display Bezel.

A CCFL, (Or two of them), uses a screen Inverter.
LED backlighting however, may or may not use a screen Inverter.

Using LED's for backlighting is relatively new, when discussing backlighting technology.
Some of the first designs of LED backlighting does use a screen Inverter.
Newer designs do not seem to.

90 PERCENT OF THE TIME the problem can be attributed to a bad screen Inverter.

It's one of two things, either it's the backlight inverter or it's the switch which tells the laptop the lid is closed.

The backlight inverter is what powers the lamps in the back of the screen.They aren't expensive, but a computer shop will probably charge you an arm and a leg to replace.

The switch tells it to turn the backlight off when the lids is down to save power.

If it's the switch, you can disconnect it by following this guide http://forum.notebookreview.com/showthre… and http://forum.notebookreview.com/showthre… according to that if it thinks the lid it will turn the blue touchpad LED orange to indicate the touchpad is locked.

probably wont need a new screen, its probably got led backlights in this is the case these may of been dying, take out the screen and if you can see leds switch it on and see if the leds light up, if now just replace them.

If it uses a bulb in the screen then you can try to get a replacement bulb or just get the whole screen.

There is a slight chance that it could be the backlight circuit in which case changing the backlight/screen wont help.

If you have a multimeter test that the backlight for voltage, to make sure it not the backlight power supply

This model laptop uses a CCFL lamp for the backlight, it does not use LEDs for backlighting.
The CCFL lamp is attached to an inverter which supplies high voltage to this lamp.
For details on how to install and or replace CCFL lamps go to
www.lcdparts.net for information and parts.

I assume you are not replacing the whole LCD screen.

try to insert the battery charger into the laptop without the battery.