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CHAPTER 6. PRECAUTIONS

1. PRECAUTIONS ON FUNCTION AND PERFORMANCE OF SYSTEM

• The picture may turn to disorder temporarily due to power discharge inside the CRT tube, but it will recover automatically
after a few seconds. In the new CRT, the very slight amount of impurities remaining inside (in vacuum) may occasionally
evaporate when hit with electron beam. However, this will not occur after the CRT has been used for 100 to 200 hours.
• When the power remains off for some time, it may indicate that a fault has occurred inside. (malfunction of parts). Turn off
the main power switch of the multi-projection unit, and after several seconds, turn it on again.
If the power goes off again, it indicates a fault. If it works normally, it indicates abnormal operations due to external factor
and will not affect operations thereafter.
• If the screen color and brightness is abnormal or the switches do not function, turn off the main power switch once and turn
it on again several seconds later.
• In some cases, the screen from appear bluish when seen from the left and slightly reddish when seen from the right. This
phenomenon called color shift is inevitable due to the structure of the projection system in which the R G, B tubes are lined
up and light is projected from the rear.
• When the one image (still image and caption) is displayed for a long period of time, the image will stick onto the screen and
cannot be removed. As this is inevitable due to the projection system, it must be resolved through software contents,
displaying method, system structure, etc.
• When bright images are displayed in the dark, the light reflected on the lens will shine in the darkness slightly. This phe-
nomenon called tube-inside reflection is inevitable due to the structure of the projection whose CRT light has been ex-
panded using the lens. (Fig. 6-1.)
(fig.6-1)