Service Procedures And Adjustments; Solid State Temperature Control Calibration - Vulcan-Hart ML-126743 Service Manual

VC4E & VC6E Series Full Size Electric Convection Ovens - SERVICE PROCEDURES AND ADJUSTMENTS

SERVICE PROCEDURES AND ADJUSTMENTS

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
UNITS BEFORE JUNE 2013
1. Place a thermocouple in geometric center of
oven cavity.
2. Set ON-OFF-COOL DOWN switch to ON.
3. Set temperature control dial to 350°F.
4. Allow oven temperature to stabilize (normally 3
cycles).
5. Record temperature at which Heat lamp goes
OFF and comes ON for at least two complete
heating cycles.
6. Calculate differential by subtracting temperature
indicated when lamp goes out from temperature
indicated when lamp comes on.
Differential = Heat lamp OFF - Heat lamp ON
Example: 360° (lamp off) - 340° (lamp on) =
20°
A. Calculated differential should be less than
20°F.
1) If differential is less than 20°F,
temperature control circuit is
functioning properly.
a. Proceed to Step 7.
2) If differential is more than 20°F:
a. Check temperature probe as
outlined under TEMPERATURE
PROBE TEST (SOLID STATE
CONTROL).
b. If probe is functioning properly
then temperature control is
malfunctioning.
a)
F25105 Rev. B (0217)
Certain procedures in this section require electrical test or measurements while
Install a replacement
temperature control and
check calibration.
7. Calculate average temperature by adding
temperature indicated when lamp goes out to
temperature indicated when 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 average temperature is less than 10°F
from dial setting, thermostat is properly
calibrated.
B. If average temperature is more than 10°F
from dial setting, thermostat calibration
must be adjusted.
1)
2)
Page 20 of 64
Loosen temperature control knob set
screw and remove knob from stem.
Loosen temperature control mounting
screws only enough to rotate control.
a. Place thumb and forefinger on
mounting screw heads, apply
pressure and slightly rotate screw
heads (body of control) in slot.
Rotate clockwise to increase
temperature and
counterclockwise to decrease.
b. Center stem (Fig. 36) in opening
and re-tighten temperature
control mounting screws.