[sane-devel] Rainbow couloured stripes = DC adapter problem?

[Novak Levente]

Hi all,

Maybe somebody can give me a hint: I have a Microtek Phantom 636cx
(CIS-based) scanner which used to work wery well up to the day when the
AC/DC adapter went away. I bought a new generic 12V/1.2A DC adapter but
the scans now have slight rainbow stripes, depending on the resolution (or
the speed of the scan head instead?).

The original AC/DC adapter was very light, I suspect it did not contain an
iron core and wires around but was perhaps electronically converting the
input voltage to 12 V DC (I am in no ways an expert in electronics, so I
may be absolutely wrong). Also, there was an inscription on this adapter
stating that it accepts a frequency of 47-63 Hz.

As with the new adaptor everything works well but there is the
aforementioned rainbow output (the scanned picture is well visible though,
these rainbow stripes are rather lightly superposed to it), I think the
scanner's electronics should be OK. 

The question: is it possible that the stripes are caused by voltage or
current unevenness while scanning? Is a certain kind of current or voltage
stabilisation needed for scanners, which can not be achieved by normal
(domestic) DC adapters?

Thanks for the response(s).

Levente