Lincoln Impinger Conveyor Ovens 1100 Series - Manual (Page 39)

LEADS ATTACHED TO THE TEMPERATURE
CONTROL BOARD: measure D. C. millivolt output of
these leads. Refer to thermocouple chart in SectionD
for proper readings. If these readings
are not achieved, replace thermocouple.
Temperature Control WITH POWER OFF: remove the
Potentiometer potentiometer leads from the temperature control
board and measure ohms from black to white leads.
The reading should be from approximately
0 to 2.5k ohms as the dial of the
potentiometer is turned throughout its full rotation.
From black to red leads, the reading should be
approximately 2.5k ohms (constant) throughout the
full rotation of the dial. If these readings are not
achieved, replace potentiometer. If the thermocouple
probe and the control potentiometer check good,
then the problem is usually with the temperature
control board.
Mercury Contactor Check for 120 VAC to the contactor coil. If voltage is
present and contactor will not activate, replace the
contactor. Also, check each contactor for proper
high voltage input and output.
Heater Elements Check the Amp. draw on each hot leg for
proper load.Check the specifications plate for rating
information.If the Amp. draw is low or high, 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 an accurate digital VOM. The element resistance
should be as follows:
220V - 30 ohms approximately
240V - 36 ohms approximately
Oven heats with switch off Mercury Contactor The mercury contactor has probably
malfunctioned 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 The main fan is equipped with internal
of motort hermal protection and will cease to
operate if overheating occurs. If the
motor overheats and then cools, this will
cause the unit to cycle on and off
intermittently. This may be caused by
improper ventilation or preventative
maintenance. Also, most of the problems
listed under “Oven will not heat” can
cause intermittent failure.
Impinger II - 1100 Series Service Manual - International 39