Epson EMP-S4 Service Manual page 80

After replacing the Photo Interrupter, always perform operation check as
C A U T I O N
described below.
1). Turn the projector on leaving the Cover Lens open.
2). After confirming that the blue image (default) is displpayed, close the
Cover Lens as shown in Figure 4-16.
If the image turns balck, there is no problem with the parts or the
connection.
SEIKO EPSON
EMP-S4
Figure 4-16.
4-18 Revision:B