Ricoh M156, Service Manual

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Other Problems
SM 6-13 M156/M157/M176/M177
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6.5 OTHER PROBLEMS
6.5.1 DARK LINES IN HALFTONE AREAS AT 75MM INTERVALS
Using the machine in a room where the humidity is too low may cause dark lines in halftone areas
at 75mm intervals. This is because low-humidity conditions tend to cause variations in light
sensitivity across the surface of the drum.
Selecting [On] for [Low Humidity Mode] under [System Settings] (User Tools) may help to prevent
these lines from appearing.
When the humidity mode setting is enabled, the drum is rotated slightly every 15 minutes. This
keeps the light sensitivity constant across the entire surface of the drum.