STERO SD3 Series, Service And Parts Manual, Page: 29 / 71

a. If voltage is not present, remove
ribbon cable connector and check
for 5VDC on pin J4-4. If not
present replace control board.
b. If voltage is present at J4-4 press
and release the ON key on
keypad. Voltage should drop to
zero on J4-4 and remain at zero
until machine is turned off.
a) If voltage does not drop to
zero or a few millivolts after
ON key is pressed, keypad
has malfunctioned.
NOTE: If the MICRO LED remains on or off constantly
when 5VDC is present on test pad, replace the control
board.
Fig. 21
b) If voltage drops to zero or just
a few millivolts after ON key
is pressed, check for
+12VDC and +5VDC on the
test pads of control board.
Fig. 22
c) If 12VDC is missing,
disconnect the display board
ribbon cable from the control
board. Recheck. If 12VDC is
present, display board has
malfunctioned.
No Fill or Rinse
1. Press the ON key on keypad to turn on machine.
2. Verify the following.
A. OPERATING CONDITIONS are satisfied as
stated at the beginning of this section.
B. Control board is programmed to operate as
an SD3.
C. Wash tank is empty or water level is below
float.
1) Float switch 1FS is open.
D. Chamber door is closed.
E. MICRO LED on control board is flashing at
a rate of 1 sec on 1 sec off.
F. DOOR LED on control board is on.
Fig. 23
1) If DOOR LED is not on with door
closed, check door interlock switch,
1LS circuit.
NOTE: With the above conditions satisfied, the fill/
rinse circuit should be active (1SOL energized). The
FILL LED on relay board will be on whenever voltage
is applied to 1SOL.
3. If machine is not filling, short the two FILL pins of
J12 on the control board together to energize
1SOL.
SD3 Series - TROUBLESHOOTING
Page 29 of 37 F45576 (1015)