3M X21i Operator's Manual page 103

3M™ Digital Projector X21i/X26i
Symptoms that may be mistaken for machine defects (continued)
Symptoms
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The signal cables are not correctly connected.
The MUTE function is working.
The volume is adjusted to an extremely low level.
The AUDIO SOURCE/SPEAKER setting is not correct.
The mode selected for HDMI AUDIO is not suitable.
The Sound button or checkbox is disabled.
The lens cover is attached.
The signal cables are not correctly connected.
The brightness is adjusted to an extremely low level.
The computer cannot detect the projector as a plug
and play monitor.
The BLANK screen is displayed.
BLANK
The USB TYPE B port is selected as the picture input
source even if MOUSE is selected for USB TYPE B.
"Waiting for connection." remains displayed even
though the USB TYPE B port is selected.
Solution
MUTE VOLUME + -
USB TYPE B
LAN
Troubleshooting
Reference
page