Scope probe set near the ballast wil produce a high freq display if the
ballast is running.
wrote in message
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I have a Compaq 8020 18.1" LCD display (guess 4/5 years old) that
suddenly shows no picture - was running windows & display blanked for
a couple of seconds then came back briefly on before going again -
screen is now black as if power is not on, though LEDs & control panel
buttons seem to operate as normal.

Flicking around with with on-off control eventually resulted in the
COMPAQ splash logo coming up (this happened once & only briefly)
before going back to darkness

I have taken the back off the unit - it seems to have 4 backlight
tube positions, though I can't see any light leaking from the metal
panel covering the actual LCD unit (I'm loathe at this point to
dismantle any further as I'm not familiar what might spring out into
my lap/into the carpet...

Do backlight tubes fail in this manner (ie suddenly) or do they tend
to slowly degrade?

As they seemingly have all gone at the same time, would this rather
point to the invertor board - do they fail in this way? What about
that tantilising flash of the Compaq splash logo?

Thanks for any info