Furuno MODEL CSH-73 Operator's Manual page 78

11-4
Gray test
This test checks for screen distortion. To escape from the test
reset the power.
GRAY TEST
 S  S
Figure 11-6 Gray test
SIO test
This test checks for proper communication between the display
unit and transceiver unit, and requires a jumper plug. To escape
from the test reset the power.
SIO TEST
DRAW SIO
IF SIO
PISO SIO1
SIO2
PIF SIO1
Figure 11-7 SIO test
= NG
= NG
= OK
= NG
= OK