Casio PX-780 Service Manual page 25

6 Restriction on the brightness of the backlight imposed by the temperature sensor
When the temperature sensor detects the increase of the temperature on the device, it automatically
restricts the brightness of the backlight. (The automatic restriction on the brightness of the backlight works
when the device is battery operated and also when it is operated by an external power source).
* This restriction has two phases; the first phase of the restriction on the brightness of the backlight has 8
steps, and backlight setting is restricted within these 8 steps. The second phase of the restriction has 9
steps, and backlight setting is restricted up to the 6th steps.
* When the setting of the brightness in the normal state or when the automatic dimmer function works
(only when the device is battery operated) is brighter than the valid range (steps) of the brightness under
restriction, the backlight automatically becomes dimmer to the brightest setting within the restricted
range; when the temperature of the device become lower which cancels the restriction, the brightness
returns to that of the original setting.
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