G'day All, I'm in the process of modding a slot load iMac G3 and i was wondering what triggers the crt to turn on when i push the power button on the front? Is it that the CRT detects a video signal from the logic board, which then turns on the screen? or does the logic board send some other kind of signal to the CRT telling it to turn on?

Thanks for any help you guys may be able to give me!