Vulcan-Hart SG4D Service Manual page 44

SG4 & SG6 Series Full Size Gas Convection Ovens - ELECTRICAL OPERATION
6. The oven will continue to cycle on the
temperature controller until the doors are opened
or master switch (S1) is turned to the OFF or
OVEN COOL position.
Timer Cycle
The timer operates independently of the heating cycle.
Additional time can be set or the timer can be turned
OFF throughout the cooking cycle.
1. With the master switch turned ON, power is
supplied to timer.
A. Set the timer to desired time.
B. Contacts 1 & 3 close, timer motor is
energized and timing down begins.
2. Time expires on timer.
A. Contacts 1 & 3 open, timer motor is de-
energized and timing stops.
B. Contacts 1 & 4 close.
1) Buzzer energized and sounds. The
buzzer continues to sound until the
timer dial is set to the OFF position or
additional time is set.
Cool Down Cycle (Solid State Temperature
Controller)
1. Conditions.
A. Oven is ON.
B. Oven cavity temperature needs to be
lowered.
C. Doors are open.
1) Convection fan de-energized.
2) Thermostat de-energized.
a. Heat light out.
b. Power removed from heat relay.
3) 24 V transformer de-energized.
4) Cooling fan de-energized.
2. Power switch (S1) turned to COOL DOWN.
A. Power to fan speed switch (S3). Set fan
speed switch to either HI or LO.
3. If door is closed, power is supplied to one side of
the following components:
A. Power ON light (Amber) comes ON.
B. Transformer (T1) energized.
F35626 Rev. B (1118)
1)
C. Component cooling fan.
D. Power to timer and oven cavity lights.
4. The oven will remain in this condition until the
master switch (S1) is turned to the OFF or ON
position.
SG4C/SG6C with Computer Controller
Schematic 426575-1 will be used to explain the
electrical sequence of operation.
Normal Cook Cycle
1. Conditions
A. Oven connected to correct voltage.
1)
2)
B. Oven properly grounded.
1)
C. Gas supply valve ON.
D. Gas combination control valve ON.
E. Power switch (S1) OFF.
F. Computer control is set up properly and
ready to use.
G. Oven lights switch (S2) ON or OFF (position
has no affect on the function of the normal
cook cycle).
H. High limit thermostat closed.
I. Oven doors closed.
Page 44 of 56
Power (24 VAC) to one side of the
following components: heat relay (R3)
normally open (N.O.) contacts, high
limit connected through the normally
closed (N.C.) contacts to the first valve
(safety) on the dual solenoid gas valve.
a. First valve (safety) on the gas
valve energized. Gas does not
flow to the burner until the second
valve (main) is energized.
L1 (hot) to power switch (S1).
L2 (neutral or second line) to one side
of the following components: oven
cavity lights, convection fan motor
common (C), transformer primary (T2),
component cooling fan and the heat
relay coil (R1).
Ground (GND) to one side of the
following components: computer
control case, no ignition light,
transformer secondary (T2), ignition
control module, the first valve (safety)
and second valve (main) on the dual
solenoid gas valve and computer
control pin 9 (C3-9).