There's a great joke about this in Stephenson's Cryptonomicon
I remember getting a borrowed 19" Sony CRT running at some insane resolution for the time, probably 1280x1024, and hearing that worrying thunk changing modes, then reading this book and reconsidering the wisdom of my custom modelines..
> One night at 3 a.m. Pekka caused this to happen, and
> immediately after the screen went black and made that
> clunking noise, it exploded in his face. The front of the
> picture tube was made of heavy glass (it had to be, to
> withstand the internal vacuum) which fragmented and spread
> into Pekka's face, neck and upper body. The very same
> phosphors that had been glowing beneath the sweeping
> electron beam, moments before, were now physically
> embedded in his flesh.
Might be true, but at least I have the untimely demise of a CRT screen on my conscience.
Got qbasic, some assembler, and a list of interrupt vectors from somwhere. Messing with int 10h, and activating each individual video mode to see what happens. Somewhere halfway the list I find 'character generator video ram access' or something. I remember thinking it sounded really cool. Anyway, activate!
Today I suppose what happened was that the horizontal and vertical retrace got switched off, and the electron beam concentrates on the center of the screen instead of going everywhere. Or maybe not, you tell me.
I do know what happened next: The screen starts to make actual noise! Something wobbling starting silent and getting louder, straight from some third rate sci fi movie: wowowowowowoewoeoeWOEWOE. It can only guess it took a few seconds, but I heard al kinds of exploding monitor horror stories, so I am scared like hell. A few seconds later, I unstiffen and pull the power plug, not the best course of action but at least the fastest.
Repower, and there is a huge purple blotch on screen. Oh dear. After a few second it shrinks away to the center and disappears. For the next month, this keeps on happening every time the screen gets powered on.
I think it was 2 months later when my dad was sick of the display vageueness that had studdenly started and finally replaced it.('Did you do anything?' - ' Who me'? + Put on the 'I know nothing, Im from Barcelona' face) No idea if parents ever knew what happened (It's about 25 years ago at this point).
Friend of mine says every comptent engineer needs to destroy at least 1 piece of expensive hardware. So I hope I'm competent, but at least I learned a healthy respect for hardware that day.
I have an old, slightly blurry CRT here that seems to have a broken vertical sync line on it. Last time I turned it on it exhibited the same effect (gigantic intense horizontal line in the middle). I knew that many electrons was going to wear out the phosphors so I reacted quickly too (it didn't make any noise though) - in my case I found that some mild percussive maintenance restored everything.
Oh man, calculating modelines was some serious voodoo back in the day. Good luck if you didn't have the manual to look up your monitor's timings. Compounding the whole thing was the serious fear that you could actually damage your monitor if you got the settings too far off. Ah, the good old days...
