Vulcan-Hart SG4D Service Manual page 43

SG4 & SG6 Series Full Size Gas Convection Ovens - ELECTRICAL OPERATION
A. Oven connected to correct voltage.
1) L1 (HOT) to power switch (S1).
2) L2 (neutral or second line) to one side
of the following components: L1 of the
power level control, power ON light,
heat light, temperature controller board
terminal 9 (120VAC) or terminal 10
(208-240 VAC), oven cavity lights,
buzzer, timer motor, heat relay coil
(R3), convection fan motor common
(C), transformer primary T1), motor
speed (Hi/Low) relay coil (R1), hold
relay coil (R2) and the component
cooling fan.
B. Oven properly grounded.
C. Gas supply valve ON.
D. Gas combination control valve ON.
E. Power switch (S1) OFF.
F. Oven light switch (S2) ON/OFF (position
has no affect on the function of the normal
cooking cycle).
G. Temperature controller dial set to lowest
temperature (fully counterclockwise).
H. High limit switch closed (position has no
affect on the function of the normal cooking
cycle).
I. Timer in the OFF position.
J. Oven doors closed.
K. Door switch contacts closed.
L. Oven cavity temperature below 140°F.
M. Power level switch to 100%.
2. Set temperature controller dial to desired
temperature.
A. Contacts J3 and J5 close.
3. Power switch (S1) is turned ON.
NOTE: Power is available to the oven light switch
A. Component cooling fan energized.
B. ON light (amber) is lit.
C. Power to timer terminal C.
D. Transformer (T1) energized.
1) Power (24 VAC) to one side of the
following components: heat relay (R3)
normally open (N.O.) contact.
2)
3)
E. Heating light is lit.
F. Power to one side of centrifugal switch.
G. Convection fan motor is energized through
(S3) high-low.
1)
H. Heat relay is energized.
1)
4. Heating circuit is powered.
A. No ignition light (red) comes ON.
B. Module performs a self diagnostic test for 4
seconds.
C. Second valve (main) on the gas valve is
energized. Gas starts to flow to burners.
D. Sparking begins, the no ignition light goes
out and burners light.
NOTE: Sparking continues for up to 7 seconds or until
a flame is established on both burners. If a flame is
sensed on both burners, the no ignition light stays out
and burner remains lit. If a flame is not sensed on both
burners after 7 seconds of sparking, the no ignition
light comes back on, second valve (main) on the gas
valve is de-energized and gas flow to the burner stops.
Ignition trial cycle repeats after a 15 second purge
between cycles for two additional tries before locking
out. To reset after a lockout, turn power switch (S1)
OFF then ON.
5. Oven reaches set temperature.
A. Temperature controller de-energizes
internal relay and the normally open (N.O.)
contacts open.
1)
B. Power removed from heat relay.
C. Heat relay normally open (N.O.) contacts
OPEN.
D. Power removed from heating circuit.
1)
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First valve (safety) on the gas valve
energized. Gas does not flow to the
burner until the 2nd valve (main) is
energized.
Ignition module energized.
When the convection fan motor
reaches operating speed, the
centrifugal switch (N.O.) on the motor
closes.
N.O. contacts close.
Heat light goes out.
Second gas valve de-energized.
F35626 Rev. B (1118)