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Impinger I -–1000 Series Service Manual - International 10
SEQUENCE OF OPERATIONS 1042 / 1043 / 1242 / 1243
MODEL 1042 - 240V - 50HZ - NATURAL GAS
MODEL 1043 - 240V - 50HZ - L.P. GAS
MODEL 1242 - 240V - 50HZ - NATURAL GAS/DUAL BELT
MODEL 1243 - 240V - 50HZ - L.P.GAS/DUAL BELT
POWER SUPPLY Electrical Power to be supplied to the Oven by a three conductor service.
Black conductor is Hot
Red conductor is Neutral
Green conductor is Ground
CONTROL BOX AUTO
COOL DOWN
When the temperature in the Control Box reaches 120°F + 3°, the Cooling Fan
Thermostat will switch power to the Control Box Cooling Fan. The Thermostat will
interrupt power to the Cooling Fan when the Control Box temperature falls to 100°F +
3°.
MAIN FAN CIRCUIT Electrical power is permanently supplied to the normally open contacts of the Double
Pole Main Fan Relay, the Cooling Fan Thermostat, the normally open Double Pole
Main Fan Switch, and the normally open Cool Down Thermostat (thermostat closes
at 160°F and opens at 140°F). Closing the Main Fan Switch supplies 240 VAC
through a 3A Fuse to the primary of the control circuit Step Down Transformer. The
Transformer steps the voltage down to 120 VAC for the control circuit. 120 VAC is
supplied to the coil of the Double Pole Main Fan Relay. The coil of the relay is
energized. The normally open contacts now close, energizing the Main Fan Motor
through one 10A Fuse. Closing the Fan Switch also supplies power to the Cooling
Fan, the 12.6 VAC Transformer the Burner and Conveyor Switches.
TRANSFORMER (12.6
VAC)
Upon closure of the Fan Switch, 120 VAC is supplied to the primary of the 12.6 VAC
Transformer. The Transformer steps the voltage down to 12.6 VAC (normally 13 to
14 VAC) with a center tap, and supplies power to the Time/Temp Display. The
voltage from each leg of the Transformer's secondary to the center tap should be
one half of the secondary voltage.
BURNER CIRCUIT Closing the Fan Switch and the normally open Burner Switch supplies 120 VAC
through the Air Pressure Switch, to the Temperature Control Board, the normally
open contacts of the Burner Motor Relay (Burner Motor Relay discontinued after S/N
14791) and the primary of the 24 VAC Transformer. The transformer's secondary
supplies 24 VAC to the burner motor relay coil (the normally open contacts close
within 30 seconds), and the normally open Centrifugal Switch. When the relay
contacts close, the Burner Blower Motor is energized. As this motor reaches approx.
1,600 R.P.M its internal centrifugal switch closes, supplying 24 VAC to the Gas
Control Valve. When the Gas Control Valve is supplied with 24 VAC, the pilot valve
is energized, and the igniter circuit is energized. Ignition should now occur. After pilot
flame is proven, the Main Gas Valve is energized. The Burner Indicator Light is also
energized.
TEMPERATURE
CONTROL
CONVEYOR DRIVE
(S/N Q14790 & Below,
1200 series
S/N Q14973 & Below,
1000 series)
(S/N Q14791 & Above,
1200 series
S/N Q14974 & Above,
1000 series refer to
Pg. 9)
Closing the Fan Switch and Burner Switch supplies 120 VAC to the Temperature
Control Board. The 1K or 1000 ohm Temperature Potentiometer is adjusted to
desired temperature. The Thermocouple will provide varying millivolts to the
Temperature Controller. The Temperature Controller supplies 120 VAC to the
Solenoid Valve at intermittent intervals to maintain desired temperature.
Closing the fan switch and the normally open conveyor switch supplies 120 VAC to
the Motor Control Board. AC volts are converted to DC volts and are supplied to the
Conveyor Motor at terminals A+ and A-. Adjustment of the Speed Control
Potentiometer (5,000 ohm 10 turn ) will change resistance at terminals P1, P2, and
P3 varying the DC voltage to the motor. The speed of the conveyor motor will
increase or decrease as the DC voltage from the board increases or decreases
respectively. As the motor turns, it drives both the reducer gearbox and the tach.
generator. The tach. generator is a DC voltage generator which supplies a voltage to
the DC motor control board and is used as a reference for maintaining a constant
conveyor speed.