[X4U] Leaving an iMac running 24/7

[dledger at ivdcs.demon.co.uk]

>From: Michael Elliott <michaelelliott at mac.com>
>
>Sorry to be so ignorant, but what is a "flyback failure"?
>
>Michael

In a CRT display the electron beam causing the dot scans the face of the tube left to right, top to bottom. A linearly increasing current in some of the coils round the back of the tube move the dot left to right. (The others do up-down). The current is then reversed rapidly to start the next scan line. This is known as flyback. This rapid change in current is also used to generate the high voltage needed to propel the electrons at the screen via a well insulated transformer and rectifier. Because of the high voltage, high currents, and resulting high temeperatures in this bit of circuitry, this 'flyback' circuitry tends to be the first bit to fail.

David