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Impinger II – Advantage Digital Express Service Manual - Domestic
18
If there is a read-out on the control, set the control
to maximum temperature (see installation
operations manual for temperature adjustment).
With the control set at maximum temperature,
check for supply voltage at mercury contactor. If
there is voltage at the mercury contactor, proceed
to “mercury contactor” for next check. If there is no
voltage at the mercury contactor, trace wiring back
to the oven control. If there is no voltage output at
the oven control, check the read-out on the
control. If the control reads “PROBE FAIL”, this
indicates that the thermocouple has failed or
become disconnected from the oven control.
Thermocouple 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 “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
voltage output to the mercury contactor, replace
the oven control. If there is voltage output to the
mercury contactor, proceed.
Mercury contactor Check for supply voltage to the contactor coil. If
voltage is present and the contactor will not
activate, replace the mercury contactor. Also
check each contactor for high voltage input and
output.
Heating element(s) Check the Amp draw on each power leg for proper
load. Check the specification plate for rating
information. If the amp draw is high or low, check
the individual elements for opens, shorts and
proper resistance.
WITH POWER OFF: To check resistance of the
elements, remove all leads from the elements and
use a digital multimeter.
The element resistance is should be as follows:
208V – 27 ohms approx.
240V – 36 ohms approx.
Replace heating elements as needed.
Oven heats with switch off Mercury contactor The mercury contactor has probably failed in the
closed position. If there is no voltage to the
operating coil, but there is high voltage at the
contactor output, replace the mercury contactor.
Intermittent heating Thermal/overload of motor The main fan motor is equipped with internal