CRTs

[CTho9305]

What is the red wire? I know its supposed to be dangerous... being stupid, my friends and I took apart a CRT, and it occured to me I don't really know what anything in there is. Anyway, nobody got electrocuted but evidently the CRT is much more than just a gun with some phosphor at the front.

 

[Jerboy]

<< What is the red wire? I know its supposed to be dangerous... being stupid, my friends and I took apart a CRT, and it occured to me I don't really know what anything in there is. Anyway, nobody got electrocuted but evidently the CRT is much more than just a gun with some phosphor at the front. >>




Thats called anode. It is connected right to the front of the screen and the potential difference between it and the cathode is about 20kV. When electron guy is turned on, it shoots cathrode ray(hence cathode ray tube) toward the shadow mask.

 

[CTho9305]

thanks. so the front of the screen is very positive, and the back is ground? makes sense. so what keeps you from getting killed when you touch the front of the screen? is there another grounded layer at the very front?

Interesting... the big black thing hooked up to the anode has lots of pins...is it more than just a simple transformer?

 

[Jerboy]

<< thanks. so the front of the screen is very positive, and the back is ground? makes sense. so what keeps you from getting killed when you touch the front of the screen? is there another grounded layer at the very front?

Interesting... the big black thing hooked up to the anode has lots of pins...is it more than just a simple transformer? >>



The glass keeps you from getting killed. It is not conductive, however due to the presence of high voltage, it does build up electrostatic charge and this is why negatively charged dusts are attracted to postively charged screen surface. Electrostatic dust catcher works in same concept.

 

[kamiam]

<< Interesting... the big black thing hooked up to the anode has lots of pins...is it more than just a simple transformer? >> >>

its called a flyback transformer...it takes the horizontal pulse signal from the horizontal output transistor, and bumps it up to the 20KV-31KV range depending on the size of the screen. the FBT (flyback) also usually developes other "power up" supply voltages, to run the rest of the chassis as well as control signals that monitor the voltages developed by the FBT ...and yes glass is an insulator,ever look up at the old telephone poles/wires...they used glass insulators on the wires at the cross-ties when crossing the poles