[Duo2400] Re: Duo 280c Screen "Whiteout"

[Ben Smith (QM Systems)]

> -----Original Message-----
> From: Duo/2400 List
> [mailto:DuoList at lists.themacintoshguy.com]On Behalf
> Of Jackie Lund
> Sent: Monday, December 16, 2002 8:54 PM
> To: Duo/2400 List
> Subject: [Duo2400] Re: Duo 280c Screen "Whiteout"
>
>
> Other than the lamp and the inverter board, what other
> parts would you
> recommend switching, since neither of those replacements
> had any effect?
>

Check the supplies to the inverter board, there should be a constant
voltage (12V?) and a second input that controls the brightness, this
second voltage should change as you adjust the brightness, also there
should be an inhibit line to turn the inverter off when the machine
sleeps.

This has just reminded me of a common but easily overlooked fault on
many notebooks, CHECK THE LID SWITCH!!! (sorry for the cap's but it is
easily overlooked), there is a switch that signals that the lid is
shut, it switches the inverter off, if it is damaged or stuck then the
inverter will never power on.

Unfortunately I don't have any schematics, so I cannot tell you which
line is which, the best thing is if you can borrow a working unit and
compare the various lines to the inverter board.
If there is no power to the board then check the motherboard, there is
probably a fuse in the DC section for the inverter power, other than
that I cannot offer any more help (unless you are in the UK then I
could take a look at it for you.)
Ben.