Yet another work-related use of my SureFire 6P

One of the little "technician tricks" i use to diagnose a dead laptop screen is to shine a flashlight thru the Apple logo on the back of a PowerBook/iBook, as it will illuminate an Apple logo sized patch of screen, enough to tell if the screen is bad, or just the backlight

a few minutes ago i was trying to see if the iBook i was working on had a dead screen, or if it was completely dead, i grabbed my 6P and shone it thru the Apple logo, nothing

on a whim, i then held the bezel up to the front of the screen and hit the momentary....

it illuminated the screen from the front, and actually lit a prety good sized patch of screen (the P61 lit up the whole screen when held in the lower right corner....)

so i decided to try my other EDC lights....

Fenix L1S; barely 1/4 of the 6P
Inova X5; less than the Fenix.....

only the Surefire had the raw horsepower to do it....

and yes, turns out the 'Book was dead, sadly

SureFire 6P to diagnose a laptop screen? So many uses. . .Enjoy!

Time for that new IMac—

Very interesting, never knew about this trick of the trade.

Please provide more details on the use of flashlight to check laptop screen.

What to expect from a working laptop screen ? Thanks.

Funny you should mention that, when my last G3 Ibook died that was the way I checked the computer. Not a technician here but having a SF M6 wasn't a bad thing....

well, when you come right down to it, a laptop screen (or any other LCD for that matter....) is a pretty basic thing, the actual LCD module itself is about 1/8" thick and is a multilayer glass sandwich (mmmm.....sandwich), 90% of what you see as an LCD display is the backlighting assembly

the display is lit by flourescent tubes (usually 2, one at the base of the display, one at the top), on a laptop, these tubes are extremely thin and delicate, about the diameter of a #2 pencil lead, when illuminated, they shine thru a diffuser and 2 polarizer sheets to illuminate the screen

on PowerBooks and iBooks, the Apple logo on the cover is illuminated by the LCD backlight tubes (there's a cutout in the aluminum EMI shield to allow light to illuminate the logo)

in the event of a backlighting failure, the display is still displaying an image, yet the screen itself is too dark to show any detail, if the light hits it *just right*, you can sometimes barely make out images on the screen

shining a flashlight thru the Apple logo illuminates a small patch of screen, similar to the way the backlight tubes do, most flashlights are not powerful enough to illuminate the display from the front though, SureFires are, the light from the SF is basically bouncing off the diffuser panel and weakly illuminating the display

Are you an Apple Genius, Mactech?

I found that in really bright sunlight, I could turn off the backlight on my Powerbook and read things if there was enough contrast -- lit from the front, that is. Handy, but not really.

I used, not sure which light it was, I think it was my Fenix actualy to test an LCD monitor that quit working by shining at the front.