Lincoln Impringer Conveyor Oven 1200 - Manual (Page 11)

Impinger I -–1000 Series Service Manual - International 11
TIME/TEMP
DISPLAY(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) 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 infra-red 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.