Epson PowerLite 7550C User Manual page 160

Then check that the image source is selected correctly. If your
projector is attached to a Macintosh, make sure that the DIP
switches on your Macintosh desktop adapter are set correctly. (See
your Macintosh documentation if you need instructions.)
When NO SIGNAL is displayed, you can't access any options on
the Video menu except Auto. Try turning the Auto Set Up feature
off, then restart your computer and manually adjust the Tracking
and Sync settings.
The computer's power management may cause the screen to go
blank or display NO SIGNAL.
A blank screen is displayed.
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The projector can't interpret the computer signal. Verify the display
format (see page 153). When you see a blank screen, you can't
access the projector menus.
The image or parts of the image are blurred or not in focus.
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Adjust the zoom and focus lens rings.
Try adjusting the Tracking and Sync buttons on the projector's
control panel or remote control.
Adjust the Brightness and Contrast settings on the Video menu. If
there is no video for 30 minutes, the projector goes into sleep mode
and the lamp is turned off.
There may be dirt or smears on the lens. Clean the lens as described
on page 132.
Problems with the Image or Sound
147