Lincoln 1400 Temp Display out or, NOTE: Time/Temp displays, inaccurate, sensor, Thermistor Probe

Temp Display out or	NOTE: Time/Temp displays	Place your pyrometer thermocouple into the center
inaccurate	use two types of temperature	between fingers T2 and T3 in the oven. Disconnect
	sensor, Thermistor Probe – 2	the yellow tipped thermistor leads from the
	yellow wires Thermocouple	time/temp. terminals 9 and 10. Measure the
	Probe 1 red wire and 1 white	resistance of the thermistor probe. See chart in
	wire	Section D for proper resistance readings.
	Thermistor Probe	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.
	Erratic time/temp display	If strange or unusual behavior is experienced such
		as a rolling of numbers, lock up at a given number,
		first check for a display circuit lock up. This can be
		caused by a voltage spike or surge. To eliminate
		this condition remove power from the time/temp.
		display by shutting off the main fan switch, or if
		display stays on, (older models) circuit breaker
		interruption may be required. This should eliminate
		the problem. If the problem continues, jumper the
		two fuses in the red wires leading from the 12.6
		VAC transformer to the display. If this does not
		solve the problem, it may be coming in through the
		commercial power lines. Suggest that customer
		contact his power company for evaluation.
	Temp Display inaccurate	Perform the power supply check, the thermistor
	erratic, or inoperative	probe check, and then perform the time/temp
		simulator test. Refer to page 51 for instructions.
		Remember, when using the time/temp simulator,
		remove all the leads from the back of the display
		except the 3 power leads. After completion of this
		test and if reinstalling back into the oven, the dip
		switches must be reset for oven operation.
	Time display inaccurate	Perform all checks as in the above evaluation. If
	erratic, or inoperative	the time check is okay, refer to the next section
		optical encoder.
	Optical Encoder	The above time/temp test should have already
		been performed. Remove dust cover from the
		gearmotor and inspect the coupling and encoder
		disc. The coupling set screws should be tight and
		not slipping on the motor shaft or the tach.
		generator shaft. The encoder disc should be firmly
		attached to the coupling and not warped. Check
		the positioning of the optical encoder disc. The disc
		should not be touching the optical encoder
		assembly and the encoder assembly should be
		mounted so it is squarely facing the coupling shaft.
		This is to allow the infrared beams to be broken by
		the encoder disc. If all this is okay, then replace the
		optical encoder assembly.

30 Impinger I -–1000 Series Service Manual - Domestic