Lincoln 1421-000-E, 1455, 1454 service manual With Power on and Thermocouple

		24VAC at transformer secondary. If there is primary
		voltage, but no secondary voltage, replace control
		transformer.
	Oven control	Check for 24VAC supply to oven control. If no voltage is
		present, trace wiring back to control transformer. Check
		for supply voltage to oven control. If no voltage is
		present, trace wiring back to hi-limit thermostat. If
		voltage is present, check for a read-out on the display. If
		there is no read-out on the display, replace oven control.
		If there is a read-out on the display, set the oven control
		to maximum temperature (see installation operations
		manual for temperature adjustment). With the oven
		control at maximum temperature, check for supply
		voltage to the heat contactor. If there is voltage at the
		heat contactor, proceed to “Heat contactor “. If there is
		no voltage at the heat contactor, trace wiring back to the
		oven control. If there is no voltage output at the oven
		control, check the read-out on the oven control. If the
		oven control reads “PROBE FAIL” this indicates that the
		thermocouple has failed or become disconnected from
		the oven control
	Contactor, hi-limit (Model	Check for supply voltage to contactor coil. If no voltage
	1421-000-E only)	is present, trace wiring back to oven cavity hi-limit
		thermostat. If supply voltage is present at the coil, check
		to see that contacts are closed. If there is voltage to the
		coil and the contacts are not closed, replace contactor.
	Thermocouple	Check to see that the thermocouple is securely
		connected to the oven control. If the thermocouple is
		connected to the oven control, and the display indicates
		“PROBE FAIL”, disconnect the thermocouple from the
		oven control and measure the resistance of the
		thermocouple. The thermocouple should read approx.
		11Ω. If these readings are not achieved, replace the
		thermocouple. If these readings are correct, proceed.
	Oven control	If the thermocouple checks good, but the oven control
		display indicates that there is a thermocouple failure,
		replace the oven control. If the oven control indicates a
		temperature reading, but the oven will not heat, proceed.
	Thermocouple	WITH POWER ON AND THERMOCOUPLE
		ATTACHED TO THE OVEN CONTROL: Measure the
		DC millivolt output of the thermocouple. Refer to the
		thermocouple chart (located in the “Removal” section of
		the manual) for proper millivolt readings. If these
		readings are not achieved, replace thermocouple.
	Oven control	If the thermocouple checks good, but there is no supply
		voltage output to the temperature regulation valve,
		replace the oven control. If there is supply voltage output
		to the heat contactor, proceed.
	Heat contactor	Check for supply voltage to the heat contactor. If voltage
		is present, listen for contacts to open and close. Also
		check for opens or shorts in the operating coil. Replace
		heat contactor as needed.
Intermittent heating	Thermal/overload of main fan	The main fan motor is equipped with internal thermal
	motor	protection and will cease to operate if overheating
		occurs. As the motor overheats and cool, this will cause
		the heating system to cycle on and off intermittently.
		Improper ventilation or lack of preventive maintenance
		may cause this problem. Also most of the problems
		listed under “Oven will not heat” can cause intermittent
		failure.
Conveyor will not run	Incoming power supply	Check circuit breaker, reset if required. Check power

Impinger I -–Adv Digital – Electric Service Manual - International 7