Service Procedures And Adjustments; Solid State Temperature Control Calibration - Vulcan-Hart VC4EC Service Manual

FULL SIZE ELECTRIC CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS

SERVICE PROCEDURES AND ADJUSTMENTS

Certain procedures in this section require electrical test or measurements while power is
applied to the machine. Exercise extreme caution at all times. If test points are not easily accessible,
disconnect power and follow lockout / tagout procedures, attach test equipment and reapply power to
test.
SOLID STATE TEMPERATURE
CONTROL CALIBRATION
1. Place a thermocouple in the geometric center of
the oven cavity.
2. Set the power switch to ON.
3. Set the temperature control dial to 350 °F.
4. Allow the oven temperature to stabilize
(normally 3 cycles).
5. Record the temperature at which the Heat lamp
goes OFF and comes ON for at least two
complete heating cycles.
6. Calculate the differential by subtracting the
temperature indicated when the lamp goes out
from the temperature indicated when the lamp
comes on.
A. The differential calculated should be less
than 20 °F.
1) If the differential is 20 °F or less, the
temperature control circuit is
functioning properly.
a. Proceed to step 7.
2) If the differential is more than 20 °F:
a. Check the temperature probe as
outlined under "TEMPERATURE
PROBE TEST (SOLID STATE
CONTROL)".
b. If the probe is functioning
properly then temperature control
is malfunctioning.
a)
7. Calculate the average temperature by adding
the temperature indicated when the lamp goes
out to the temperature indicated when the lamp
comes on and dividing this answer by 2.
A. If the average temperature is 10 °F or
less, from the dial setting, the thermostat is
properly calibrated.
Install a replacement
temperature control and
check calibration.
B. If the average temperature is more than
10 °F from the dial setting, the thermostat
calibration must be adjusted.
1)
2)
Page 17 of 60
Loosen the temperature control knob
set screw and remove the knob from
the stem.
Loosen temperature control mounting
screws only enough to rotate the
control.
a. Place thumb and forefinger on
the head of the mounting screws,
apply pressure and slightly rotate
the screw heads (body of control)
in the slot. Rotate clockwise to
increase temperature and
counterclockwise to decrease.
b. Center the stem in the opening
and re-tighten the temperature
control mounting screws.
c. Replace knob and re-tighten set
screw.
d. Rotate the knob to the lowest
temperature setting then back to
350°F.
e. Repeat the average temperature
calculation in step 7.
F25105 (Rev. A, October 2007)