Repair manual

OPERATION
3-16
4. On a call for heat from the cooking computer
(1), as sensed by an RTD probe (18), the heat
relay (4) closes sending 115 VAC to one termiĆ
nal of a N.C. SPST thermal switch (19). The
switch toggles if the temperature passing its
face exceeds the rating on the back of the
switch. If the switch is closed, 115 VAC is delivĆ
ered to the burner control valve (20). This valve
opens sending gas to the flame blower (21) for
ignition.
NOTE: The RTD probe is located in front of the
combustion motor. It should be
checked with an ohm meter. The SPST
thermal switch is located in the rear of
the convection fan compartment.
5. The conveyor is driven by an open loop DC
control system consisting of a DC speed conĆ
trol board (5), a 130 VDC motor (22) and the
DAC located in the cooking computer (1). If a
time is programmed into the cooking computĆ
er, a voltage ranging between .47 and 4.7 is apĆ
plied to the DC speed control board. The outĆ
put voltage measured at A1 and A2 of the
board to the motor varies from 20 to130 VDC
based on the DAC voltage applied to the board
or the time programmed into the computer.
NOTE: The DAC receives 20 VDC from the
speed control boards. The DAC reĆ
turns a portion of the voltage (between
.47 and 4.7 VDC). The amount of voltĆ
age is dependent on the time proĆ
grammed into the computer.
NOTE: This type of system does not sense the
weight of the product and will slow
down slightly if the belt is fully loaded.