Lincoln Impringer Conveyor Oven 1200 - Manual (Page 51)

Impinger I -–1000 Series Service Manual - International 51
Conveyor Drive(Stepper)
Motor Check the drive sprocket on motor output shaft to
insure that it is tight. Check motor windings
measurement should be approximately 2 ohms.
Terminals 1-5, 2-6, 3-7, 4-8. WITH POWER OFF:
Turn the motor shaft to check for jammed gear box.
If motor shaft will not turn, replace conveyor
drive(stepper) motor.
12 VAC Power Supply
(Transformer) Measure the transformer primary for a nominal 120
VAC input, if voltage is not present, trace wiring
back to the oven fan switch. Measure the
secondary output, which will normally be 12-15
VAC. Voltage across terminals 1 and 3 on the
time/temp. display should read 12-15 VAC.
Terminals 1-2 and 2-3 should be 1/2 the voltage
reading 1 to 3. If the above secondary readings are
not achieved, replace transformer. Time/Temp. Display
inoperative
Time/Temp. Display If proper voltage is present at terminal 1,2, and 3
on time/temp. display, but the display is not lighted,
recheck all connections for tightness. If time/temp.
display is still not operating, replace the time/temp.
display.
NOTE: Time/temp displays
use two types of temperature
sensor Thermistor Probe - 2
yellow wires. Thermocouple
Probe - 1 red & one white
wire Place your pyrometer thermocouple into the center
between finger T2 and T3 in the oven. Disconnect
the yellow tipped thermistor leads from the
time/temp. terminals 9 and 10. Measure the
resistance of the thermistor probe.
Thermistor Probe See chart on page 72 for proper resistance
readings. Inspect the thermistor bulb for its proper
location in its spring holder. Check for short in
leads where they enter the sensor bulb. Also check
each thermistor lead for short to ground.
Thermocouple Probe Place your pyrometer thermocouple into the center
between fingers T2 and T3 in the oven. Connect
temperature meter to thermocouple at terminals 9
& 10 on back of the time/temp display. (Be sure to
maintain proper polarity on thermocouple
connections.) Compare actual oven temperature
with the reading at the time/temp display. If the
temperature readings match, recalibrate or replace
time/temp display. If the readings do not match,
replace thermocouple probe.
Temp. Display out or
inaccurate
Power Supply If a strange or unusual behavior is experienced,
such as a rolling of numbers, or lock-up at a given
number, first check for a display circuit lock-up.
This may be caused by a voltage spike or surge in
the incoming power lines. To eliminate this
condition, remove power from time/temp. display by
shutting off the main fan switch for 15 seconds.
This should eliminate the problem. If this does not
solve the problem, it may becoming in through the
Commercial power lines. Suggest that customer
contact their power company for evaluation.