when does dpms get turned on/off?

[Fulko Hew]

I have a Dell Inspiron 6400 laptop running Fedora 8.
When I shut the lid, the screen is blanked _and_ the
backlight is turned off.

But then ~5 seconds later, the backlight is apparently turned back on
(behind a black screen)  So the florescent tube is always
running, and therefore aging.

(The same thing is happening when the screensaver kicks in and
blanks the screen and power management kicks in to turn it off.)

Can anyone shed light (pun intended) on this scenario,
and where to look, and how to fix it.

I tested my hypothesis, by shutting the lid and looking at the glow.
hen ssh'ing in, and running 'vbetool dpms off'.
and it actually turn the light off, and kept it off.
...same for 'standby' and 'suspend' options.

TIA
Fulko
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