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Impinger I -–1000 Series Service Manual - Domestic
6
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
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.
CONVEYOR DRIVE
(S/N Q14790 & Below,
1200 series
S/N Q14973 & Below
1000 series)
(S/N Q14791 & Above,
1200 series refer to Pg.
5 & 6 S/N Q14974 &
Above, 1000 series refer
to Pg. 5 & 6 (STEPPER)
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 Conveyor 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.
NOTE: The 1200 Series Ovens utilize 2 complete conveyor drive systems.
TIME/TEMP
DISPLAY(S/N Q14790 &
Below, 1200 series
S/N Q14973 & Below
1000 series)
(S/N Q14791 & Above,
1200 series refer to Pg.
5 & 6 S/N Q14974 &
Above, 1000 series refer
to Pg. 5 & 6 (STEPPER)
The Time/Temp. Display is energized when the Fan Switch is closed, supplying 120
VAC to the primary of the12.6 volt Transformer. The secondary output of the
transformer, normally 13 to 14 VAC (depending on input), with a center tap, is
supplied to terminals 1,2, and 3 of the Time/Temp. Display. The center tap is
terminal 2. The display works on a balanced input and center tap voltage to each leg
must be 1/2 the total reading.
The speed side of the Time/Temp. Display uses a slotted disc (cemented to tach.
coupling) to break the infrared light beam of the optical switch (mounted on gear
motor) producing electrical pulses that are transmitted to the display. The display
converts these pulses into a read-out of minutes and seconds. The temperature
portion of the display uses a Thermistor Probe to sense oven temperature. The
thermistor outputs a resistance proportional to the oven temperature. This resistance
is then converted by the display into a temperature reading.
NOTE* The 1200 Series Ovens use a Double Pole Double Throw Switch to connect the two
Optical Encoder Assemblies to the Time/Temp. Display. By activating the switch,
either the front or rear belt speed can be shown by the Time/Temp Display .
CONVEYOR DRIVE Closing the Oven Fan Switch supplies 120 VAC, through the Power Transformer, to
the normally open Conveyor Switch. Closing the Conveyor Switch supplies 120 VAC,
through a 3 AMP Fuse, to the primary of the Conveyor Control Transformer. The
secondary of this Transformer supplies 10 VAC and 29 VAC to the Conveyor
Control. The conveyor control supplies voltage pulses to the Conveyor Control. The
Conveyor Control Potentiometer varies the frequency of these pulses. The motor
speed will increase or decrease, as the frequency of the pulses increase or decrease
respectively.