On Mon, 10 Nov 2003, Andy Green wrote: >> Would you be willing to subject your CRT to an experimental video >> driver? I can whip up a video driver guaranteed to let the smoke >> out of your monitor for proof of concept, > >Thanks for the offer :-) but explaining the mechanism would be >a lot more useful... what exactly gets hot and why? Generally >if things are asked to operate outside their bandwidth the >signal attenuates towards nothing. As I said, older CRTs do not protect against out of range signals. Take an 8 year old 14" monitor, and set the resolution to 1600x1200@100Hz and watch it sizzle. Depends on the exact monitor, it's capabilities, what protection it has built in if any, etc. >It would be a badly designed circuit that reacted to this by >getting hot and letting out the magic smoke. Poorly designed, or just simply "older". >>assuming your monitor has no built in protection. > >What is not being protected in this instance, and do any recent >monitors lack this protection? This is what I doubt. I don't know of any modern CRT displays that lack protection, however some LCD/DFPs do. I can't name models and point my finger however, but they do exist. If someone is interested deeply in finding a model that is fryable, they can search google I suppose. >The only CRT I have left is an old Iiyama which definitely tells >me if things are too much for its creaking old bones... and has >all its magic smoke intact. Then your Iiyama monitor is protected and you don't have to worry about things. I've got 2 monitors here which do not have protection and very much would let the smoke out if sent the wrong signals. There are a _lot_ of people out there who have displays which are anywhere as old as 10 years or more, so there are definitely people who have displays which are destroyable by misconfiguring XFree86. Wether or not you specifically, or anyone else is at risk of destroying their display however very much depends on what make/model/year of display you have and wether or not it has built in out of range signal protection or not. If one is not sure, then one shouldn't experiment with signal ranges. In any case, sticking to the manufacturer supplied official ranges is a good general safe bet. -- Mike A. Harris ftp://people.redhat.com/mharris OS Systems Engineer - XFree86 maintainer - Red Hat
