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Impinger II – Advantage Digital Service Manual - International
14
connected to the oven control, and the display 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
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 supply
voltage output to the mercury contactor, replace the
oven control. If there is supply 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 should be as follows:
230V – 33 ohm.
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 at the operating coil, but
there is high voltage output from the contactor, replace
the mercury contactor.
Intermittent heating Thermal/overload of
main fan motor
The main fan motor is equipped with internal thermal
protection and will cease to operate if overheating
occurs. As the motor overheats and cools, this will
cause the heating system to cycle on and off
intermittently. Improper ventilation or lack of preventive
maintenance may cause this problem. Also, most of the
problem listed under “Oven will not heat” can cause
intermittent failure.
Conveyor will not run Incoming power supply Check breaker, reset if required. Check power plug to
be sure it is firmly in receptacle. Measure incoming
power, call power co. if needed.
Fuse, 10 amp Check, replace if necessary.
Fuse holder Check, replace if necessary.
Hi-limit thermostat, control
box
Check for voltage on both sides of switch. Terminals are
normally closed. If open, reset and test oven for proper
operation. If thermostat will not hold, and control box
temperature is not exceeding 140°F (60°C), replace
thermostat.
Switch, main fan With power off, check continuity between switch
terminals. Replace as needed.