filmscanners: Umax banding

[tflash <tflash@earthlink.net>]

My Umax 1200s flatbed has developed a nasty banding problem (in spite of
plugging it into an isolated circuit breaker). I'm calling it banding, but
this might be scans lines.

In transmissive mode it is apparent throughout. I'm talking about regularly
spaced red lines, horizontal to the CCD = perpendicular to the direction of
the scan. At magnifications above 100% one sees they are prismatic, but they
look red to me at normal viewing magnifications. Four fit inside a 35mm
sprocket hole, with their accompanying empty spaces.

Interestingly, I've just scanned a typed page in reflective mode (RGB), and
I don't see the lines in the white of the page, but I do see it along the
edges of type. The optical illusion is that the hollow spaces of the type
are filled with the lines, but at higher magnification one sees that is just
some spread off the edges, that do not connect at the center. In BW mode
there are no lines, but the edges of the type looks like they were streaked
by the lines.

Finally, if I raise the resolution of the scan it increases the line
frequency, and increases their spread.

Does this mean it's transport mechanism is beat? It didn't use to do this,
but I haven't used it for a while, and I guess it got moved around,
otherwise I don't know what might have changed.

Could giving it a new SCSI ID help? A whack in the head, or a toss out the
window?

Todd