Lincoln 1400 Series Service Manual page 13

Thermocouple Probe
Temperature Control
Solenoid Valve
Intermittent Heating AS FOLLOWS
For continuing intermittent problems, a series of test lights may be made and installed in the ovens. The lights will allow the
customer to advise the service technician a trouble code when the oven fails
The lights should be connected in the following manner:
Light#1 attached in 120 VAC line after oven fan switch.
Light #2 attached after 120 VAC contacts of oven motor centrifugal switch
Light #3 in 24 VAC Burner Transformer Secondary.
Light #4 in 24 VAC at terminal #6 of Ignition control valve.
Light #5 in 24 VAC at terminal #3 of Ignition control valve.
Light #6 in 24 VAC at terminal #1 of Ignition control valve.
CODE:
All lights off - lights of main power, main fan off, oven fan switch out.
1 on 2 off 3 off 4 off 5 off 6 off - Oven Motor Centrifugal Switch open
1 on 2 on 3 on 4 off 5 off 6 off - Burner Motor Centrifugal Switch bad.
1 on 2 on 3 on 4 on 5 0ff 6 off - Ignition Control bad
1 on 2 on 3 on 4 on 5 on 6 off - Pilot Shield missing or warped, no flame rectification, Pilot
1 on 2 on 3 on 4 on 5 on 6 on - Unit still not working Main Orifice plugged, Gas Valve bad,
Conveyor will not run Voltage Supply
3 Amp Fuse
Fuseholder
Fan Switch
Speed Adjustment
Potentiometer
Impinger I – 1400 Series Advantage Service Manual – Dom & Int'l
- Orifice plugged, or Gas Control Valve bad.
- Temperature Control bad.
- However, Main Orifice would not be intermittent problem.
Remove thermocouple leads from the temperature
control board, and measure the millivolt output of
these leads. Refer to charts on page 25 in the
adjustment section for proper readings.
Turn temperature control dial to full "on" position.
NOTE: Thermocouple must be connected. Measure
for 120 VAC across terminals "N.O." and Com., if
voltage is not present; replace control.
If voltage is present at terminals "N.O." and Com.,
check for voltage at solenoid valve. If voltage is
present, listen for valve to open and close. Also,
check for opens and shorts in coil. If solenoid valve is
defective, replace.
Both the main fan motor and burner blower motor are
equipped with thermo-protection and will cease to
operate when not cooled properly. This can cause
the units to cycle on and off intermittently. Also, most
of the problems listed under "oven will not heat" can
cause intermittent failures.
Check incoming voltage supply at line 1 to neutral.
There should be a voltage reading of 120 VAC. If not
present, check breakers.
This control fuse is located on the front panel.
Replace if defective.
Check and/or replace.
See procedure for checking on page 11.
This is a 0 to 10 K ohm, 1 turn potentiometer. With
power off, remove the black and white pot leads from
the motor control board at terminals P1, P2. Place the
meter leads on the black lead (P2) and on the white
lead (P1). Rotating the pot., slowly, from low to high,
the meter reading should show an even transition
from 0 to 10K ohms ± 5%. There should be no dead or
open spots through out the 1 turn of the pot. Check
both leads to ground. There should be no continuity to
ground. If any of the above checks fail, replace the
pot.
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