The ongoing saga of the Pentium II laptop, ca. 1997 vintage; I'm using xscreensaver, with its power management settings set to standby, shutdown, and full power off the monitor after 10 minutes, but I've noticed that even when undisturbed for a prolonged time, the backlight in the built-in LCD never shuts off. That means the tiny fluorescent tubes that provide the backlight (and which are a major job to replace, even if parts are available) will burn out in much less than the sixteen years I've had the machine so far.

Anyone know how to get the backlight to shut off under software control (it did so in Win98, which is a large part of why the display still works properly after several years of continuous machine operation as a bedside stereo) when the display is"turned off"?

Okay, I found the solution for this one. First, the BIOS settings for power management have to be enabled (they were). Second, the BIOS-level keyboard controls (this Solo 2500 model has a number of"Function" keys that bypass the OS) have to be set for Power Management to be in"DC" mode (i.e. tell the machine you're on battery); that will then apparently kill the backlight when the"monitor" powers down via ACPI. So, now, when the display shuts off, the backlight goes dark, and I'm back to preserving the hardware. Maybe I'll get another sixteen years out of this machine (though I'll have to rebuild the battery another 3-4 times in that period)...