On Fri, Jun 17, 2016 at 11:36:14AM -0400, Noel Chiappa wrote: [...] > (Parenthetically, what exactly is the mechanism that causes damage if you run > an old CRT monitor at too high a refresh rate? I assume the excessive speed > generates too much heat somewhere, and causes transistors to fail, or > something like that?)
To generate high voltage DC such as that necessary to emit an electron beam, one typically feeds an AC signal into a voltage multiplier circuit. Textbooks will show some nice clean circuits which multiply by a fixed integer, but real-world components don't read textbooks and the output voltage also varies by frequency. If one is building a fixed-frequency display (e.g. a TV), one can cut corners and save a few bob by recycling the line output frequency (~15kHz for both PAL and NTSC) to generate this AC. So if the line output frequency goes up, so can the beam voltage, possibly to dangerous levels. [...] > So is there some bizarre interlace mode, or something, that could > legitimately cause confusion over the vertical retrace? Or is the second > monitor just confused? Both are correct. There are 44 (rounded) frames per second, and 87 (rounded) fields per second.
