Lincoln 1400 Series Service Manual page 17

Thermocouple Probe
Flame Monitor
Relay, Main Burner
Valve, Temperature
Regulation
Main Flame will not Flame Monitor
stay lit
Intermittent heating As Follows
Impinger I – 1400 Series Advantage Service Manual – Dom & Int'l
Remove thermocouple leads from the temperature
control board and measure the millivolt output of these
leads. Refer to chart on Page 25 for proper readings.
If the thermocouple probe checks good, replace
temperature control.
Check for 220 VAC at terminal #1. If no voltage is
present, trace wiring back to temperature control.
Check for 220 VAC output at terminal #8. NOTE:
There is a delay of up to 2 seconds for 220 VAC
output at terminal #8. If there is no voltage output at
terminal #8, check the reset button. Replace control
as needed.
Check for 220 VAC at relay coil, if no voltage is
present, trace wiring back to flame monitor. Check for
120 VAC to relay contacts. If no voltage is present,
trace wiring back to power supply. Check to ensure
contacts are closing
Replace relay as needed. Check for 120 VAC at
valve, if no voltage is present, trace wiring back to
relay. If voltage is present, listen for valve to open and
close. Check for opens or shorts in coil. Replace as
needed.
(There should be a visible main flame at this time.) To
check for flame monitor operation, connect a digital
voltmeter (capable of measuring D.C. microamperes)
between the flame sensor and terminal #15 on the
flame monitor. The flame monitor requires a minimum
of 4 micro amp. D.C. for proof of flame. If these
readings are not achieved, replace sensor assembly.
Also check for any type of damage to flame sensor
wire and connections. If the reading is above the
minimum required, and the flame monitor will not
supply 220 VAC to the relay coil, replace the flame
monitor.
Both the main fan motor and burner blower motor are
equipped with thermal protection and will cease to
operate if overheating occurs. This can cause the
units to cycle on and off intermittently. This may be
caused by improper ventilation. Also most of the
problems listed under "oven will not heat" can cause
intermittent failure. See page 13 for test lights.
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