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 and follow Arc Flash
procedures. 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 (VC4GD/
6GD)
UNITS BEFORE JUNE 2013
1.
Place a thermocouple in the geometric center of
the oven cavity.
2.
Set the ON-OFF-COOL DOWN 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.
Differential = Heat lamp OFF - Heat lamp ON
Example: 360° (lamp off) - 340° (lamp on) =
20°
A.
The differential calculated should be
less
than 20°F.
1)
If the differential is
less
than 20°F, the
temperature control circuit is
functioning properly.
a.
2)
If the differential is
more
than 20°F:
a.
Check the temperature probe as
outlined under TEMPERATURE
PROBE TEST (VC4GD/6GD).
b.
If the probe is functioning properly
then temperature control is
malfunctioning.
a)
Install a replacement
temperature control and
check calibration.
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.
[Temp. (lamp off) + Temp. (lamp on)] ÷ 2 =
Average Temp. Example: (360° + 340°) ÷ 2 =
350°
A.
If the average temperature is
less
than 10°F
from the dial setting, the thermostat is
properly calibrated.
B.
If the average temperature is
more
than
10°F from the dial setting, the thermostat
calibration must be adjusted.
1)
Loosen the temperature control knob
set screw and remove the knob from
the stem.
2)
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.
NOTE:
Allow the oven to cycle at least two times
between adjustments before performing the
calculation.
VC4G & VC6G SERIES FULL SIZE CONVECTION OVENS - SERVICE PROCEDURES AND ADJUSTMENTS
F24682 Rev. D (1016)
Page 24 of 75
