Lincoln 1628-000-A - Manual (Page 6)

Low Profile – 1600 Series Adv Dig Electric S.M. – Int’l
6
Thermocouple probe Check to be sure that the thermocouple is securely
connected to the oven control. If the thermocouple is
connected to the oven control, and the control
indicates “LP FAIL” or “RP FAIL”, disconnect the
thermocouple from the oven control and measure the
resistance of the thermocouple. The left thermocouple
should read approx. 21
Ω . The right thermocouple
should read approx. 11 Ω . 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
voltage output to the temperature regulation valve,
replace the oven control. If there is voltage output to
the heat relay, proceed.
Oven air pressure switch Check for supply voltage at the air pressure switch, if
no voltage is present, trace wiring back to the oven
control. Check for supply voltage on both sides of
switch. If voltage is present on one side only, check
for air tube blockage. Adjust air pressure switch. If the
above fails, replace air pressure switch.
Heat relay Check for line voltage supplied to the coil of the heat
relay. If no voltage is present, trace wiring back to the
air pressure switch. If voltage is present, check to be
certain that all of the contacts are closing when the
relay is energized.. Also check for opens or shorts in
the operating coil. Replace temperature regulation
valve as needed.
Heating elements Check the Amp draw on each power lead for proper
load. Check the specification plate for proper rating
information.
If the Amp draw is high or low, check the individual
heating elements for opens, shorts and proper
resistance.
To check the resistance of the elements,
TURN OFF THE POWER!
Remove all wiring from the heating elements and use
an accurate digital meter.
The element resistance should be as follows:
220V – 29 ohms approx.
230V – 32 ohms approx.
240V – 34 ohms approx.
If all readings are not correct, replace heating
elements as needed.