Furuno CSH-53 - Manual (Page 90)

13-4
Gray test
This test checks for screen distortion. To escape from the test
reset the power.
GRAY TEST
, Q, Q
Figure 13-6 Gray test
SIO test
This test checks for proper communication between the display
unit and transmitter unit, and requires a jumper plug. To escape
from the test reset the power.
SIO TEST
DRAW
IF
PISO
PIF
SIO
SIO
SIO1
SIO2
SIO1
= NG
= NG
= OK
= NG
= OK
Figure 13-7 SIO test