HV in a laptop???

[hannobisschoff@gmail.com]

Hi, as I was hacking this laptop (basically just an euphemism for ripping it apart).
I saw this "High Voltage" sign on the back of the LCD. Can someone please explain to me what this is doing in a laptop?

 

[hannobisschoff@gmail.com]

Note the "cold cathode fluorescent lamps"
Whatever that might be.

 

[KeepItSimpleStupid]

Cold cathode = no filament. Florescent = a little mercury in a tube and a phosphor and you guesed it, a high voltage. About 300 V or so, I believe.

It's the backlight for the LCD screen. Without the light, the screen would be very dark.

New technology is LED backlit.

 

[hannobisschoff@gmail.com]

Yup, forgot to mention this is an old laptop.
LED backlit nowadays hey? So how do they generate the 300v. With a transformer, or charge pump?

 

[Noggin]

Transformer based, and fairly low current.

Edit: Post 556

 

[hannobisschoff@gmail.com]

Is the HV DC or AC?

 

[Reloadron]

They use an inverter. So as you hack away, note the backlight(s) and follow the wires. You should find the inverter power supply that drives them.

AC and give this a read.


Ron

 

[KeepItSimpleStupid]

**broken link removed**

 

[hannobisschoff@gmail.com]

Thanks guys. Usually when I'm busy with my "HACK ATTACK" I'm in such an euphoric haste, that I tend to miss these things.
As for now, I'll stop the hacking, and go to bed, since it's 2:30 in the morning in my part of the world. Cheers

Hanno