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.
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.
Post back in a Comment.
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.