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Impinger I -–1000 Series Service Manual - Domestic
26
Temperature Control Board Check for 120 VAC input to temperature control
board. If not present, check wiring from fuse holder
to temperature control board. Turn the temperature
adjustment dial to the maximum temperature
position Check for 120 VAC at coil of mercury
contactor(s). Next, short the leads of thermocouple
on the temperature control board, check for 120
VAC at coil of mercury contactor(s). If voltage is
not present, replace temperature control board. If
voltage is present proceed.
Temperature Control
Potentiometer
Potentiometer is 0 to 2.5K ohm. WITH POWER
OFF: remove the leads from the temperature
control board terminals 1, 2, and 3 and measure
ohms from black to white leads. The ohm reading
should be 0 to approximately 2.5K ohms as the dial
Thermocouple Probe Remove thermocouple leads from the temperature
control board, and measure the millivolt output of
the leads. Refer to chart in adjustment section for
proper millivolt readings.
Mercury Contactor(s) Check for 120 VAC to the contactor coil. If voltage
is present and contactor will not activate, replace
the contactor(s). Also check each contactor for
proper high voltage input and output.
50 Amp Fuses If there is no high voltage input to the mercury
contactor(s), check the 50 amp fuses and replace if
necessary.
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 . To check resistance of the
elements, turn off the power! Remove all leads
from the elements and use an accurate digital
VOM. The element resistance should be as
follows: 208V - 9.8 ohms approx. 220V - 10.5 ohms
approx. 240V - 13 ohms approx. If all readings are
not correct, replace elements as needed.
Oven heats with switch
off
Mercury Contactor(s) 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.
Voltage Supply Check incoming voltage supply at line 1 to neutral.
There should be a voltage reading of 120 VAC. If
not present, check breakers.
3 Amp Fuse This conveyor fuse is located on the front panel.
Replace if defective.
Fuse Holder Check and/or Replace.
Conveyor Switch Same procedure as for fan switch.
Conveyor will not run
(S/N 100-4389)
D. C. Motor Control Board Check for 120 VAC input to D. C. control board
across L1 and L2. Check the 3 amp fuse on the D.
C. control board. Check for D. C. voltage at
terminal F1 and F2. Voltage should be 10 VDC +
10 steady. If this voltage is not present, replace D.
C. control board. Check for D. C. voltage output to
the motor across terminals A1 and A2 (this voltage
should be approx. 125 VDC at maximum conveyor
motor speed).