Don Allen wrote:

We bought a HP ZT1135 laptop for my daughter when she went off to
college a few years ago. With the exception of a failure of the IBM
TravelStar HD (no surprise!), the unit has been very reliable. This
past weekend a problem has developed relating to the LCD display. Here
are the symptoms: the screen toggles from a normal display, to a
totally white display, to a somewhat gray display with vertical rasters
or vertical bars, and then back to a normal display . . . and, so on in
this pattern on a cyclic basis.

I connected an external monitor to the DB-15 video connector, and the
display on the external monitor is fine. I would presume this excludes
the S3 video card from a potential failure cause of the LCD display
problem.

Does anyone have any experience with such a failure with this type of
symptoms? My first thought was the LCD's power inverter circuit module,
but perhaps I should also look at the flex cable connecting the MB to
the display. I must admit I didn't move the screen on its hinges in my
initial look at the unit. Any suggestions or hints would certainly be
appreciated, as she is in dire straits without her laptop. She's now a
Senior, and in some tough classes!

TIA for any input.

Don W9CW
Yes, the ribbon cables and their plugs and connectors should be your
main suspects. Ususally a bad inverter would cause the screen to not
light up at all ot to go completely black intermittently. With a bad
inverter you could shine a bright light into the screen and maybe still
see the images it should produce.