Service manual

FULL SIZE GAS CONVECTION OVENS - ELECTRICAL OPERATION
F24682 (Rev. B, October 2007) Page 48 of 68
c. Ignition control module is
energized.
a) No ignition light (red) comes
ON, module performs a self
diagnostic test for 4
seconds, 2nd valve (main)
on the gas valve is
energized. Gas starts to flow
to the burner, sparking
begins, the NO IGNITION
light goes out and burner
lights. Sparking continues
for up to 7 seconds or until a
flame is established. If a
flame is SENSED, the NO
IGNITION light stays out
and burner remains lit.
If a flame is not SENSED
after 7 seconds of sparking,
the NO IGNITION light
comes back on, 2
nd
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.
3. Oven reaches set point temperature.
A. Computer control de-activates the 120VAC
output to heat relay (R1).
1) Heat relay (R1) de-energized and the
normally open (N.O.) contacts OPEN.
a. Power removed from ignition
control module.
a) The 2
nd
valve (main) on the
gas valve is de-energized
and gas flow to the burner
stops.
B. Oven HEAT LIGHT on the control goes
out.
C. Oven READY LIGHT on the control comes
ON.
D. Electronic beeper sounds momentarily.
4. The oven will continue to cycle on the computer
control until the doors are opened or power
switch (S1) is turned to the OFF or COOL
DOWN position.
Temperature and Time Cycle (Cooking)
NOTE: The computers internal COOK timer operates
independently of the heating cycle. Additional time
can be set or the timer can be stopped and re-
started throughout the cooking cycle.
Refer to the Instructions Manual for specific
operating instructions of the oven Computer Control.
Roast and Hold Cycle
NOTE: For a detailed explanation of the ROAST &
HOLD mode, refer to the Instructions Manual as
outlined under SETTING THE OVEN FOR ROAST &
HOLD and ROAST & HOLD OPERATION.
In ROAST & HOLD mode, the operation of the
computer control is identical to the normal Cook
Cycle with these exceptions:
1. Oven ROAST & HOLD light on the control
comes ON.
2. Convection fan speed changes from High to
Low.
A. The computer control 5VDC output from
pins C2-2 (-) and C2-8 (+) is de-activated
and SSR1 relay is de-energized.
1) Power (120VAC) is removed from
convection fan motor high speed
terminal.
B. The computer control 5VDC output from
pins C2-1 (-) and C2-8 (+) is activated and
SSR2 relay is energized.
1) Power (120VAC) is applied to the
convection fan motor low speed
terminal.
3. At the end of the ROAST time, the electronic
beeper sounds momentarily to indicate the end
of first stage cooking (oven operates normally at
the temperature and time selected until time
expires).
4. The display flashes HOLD as the oven enters
HOLD mode. This is also considered second
stage cooking (oven heating stops but product
continues to cook on residual heat).
A. Convection fan motor is de-energized.
5. After the oven temperature drops below 150°F,
the heat comes back ON and cycles as needed,
to maintain the HOLD temperature of 150°F.
A. Convection fan motor energized.
6. The oven continues to cycle in this manner until
one of the following occurs:
A. The ROAST & HOLD mode is turned OFF.
B. Power switch (S1) is turned to the OFF or
COOL DOWN position.