# 8 2 8 O p e r a t i o n a n d C a r e M a n u a l • 12.
√
S E R V I C E
THERMOSTAT/INDICATOR LIGHT
SEQUENCE
Whenever the dial thermostat is turned ON, the light
will indicate the power ON/OFF condition of the
heating cable; and consequently, the cycling of the
cabinet as it maintains the dialed cavity temperature.
If the indicator light does not illuminate after normal
start-up, the main power source, thermostat, and/or
light must be checked. If the warming cabinet does
not hold the temperature as dialed, the calibration of
the thermostat must be checked. If the warming cab-
inet fails to heat or heats continuously with the ther-
mostat “OFF,” the thermostat must be initially
checked for proper operation. If these items are
checked and found to be in order, a continuity and
resistance check of the heating cable should be
made. SEE CIRCUIT DIAGRAM.
THERMOSTAT CALIBRATION
The thermostat is precision calibrated at the factory.
Normally, no adjustment or recalibration is necessary
unless the thermostat has been mishandled in transit,
changed or abused while in service. A thermostat
with a sensing bulb operates on hydraulic pressure;
consequently, any bending of the bulb results in a
change in its volume, and alters the accuracy of the
thermostat calibration.
A thermostat should be checked or recalibrated by
placing a quality, thermal indicator at the center of
an empty holding cavity.
DO NOT CALIBRATE
WITH ANY FOOD PRODUCT IN THE CABI-
NET.
The thermostat should be set at 140°F
(60°C), and should be allowed to stabilize at that set-
ting for a minimum of one hour. Following tempera-
ture stabilization, the center of the thermal swing of
the air temperature within the cabinet should
approximately coincide with the thermostat setting.
If calibration is necessary, the calibration screw
should be adjusted with great care. The calibration
screw of the thermostat is located in the thermostat
dial shaft. With the shaft held stationary, a minute,
clockwise motion of the calibration screw apprecia-
bly lowers the thermostat setting. A reverse, or
counter-clockwise motion appreciably raises the ther-
mostat setting. After achieving the desired cycling
of the thermostat, the calibration screw must be
sealed. Place a few drops of enamel sealant directly
on the calibration screw.
(
RED NAIL POLISH OR EQUIVALENT IS
ACCEPTABLE
.)
Heating Cable Replacement Service Kit
No. 4881
includes:
CB-3045
Cable Heating Element . . . . . . . . . . . . . . . . . . . . . . .210 feet
CR-3226
Ring Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
IN-3488
Insulation Corner . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 foot
BU-3105
Shoulder Bushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
BU-3106
Cup Bushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
SL-3063
Insulating Sleeve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
TA-3540
Electrical Tape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 roll
ST-2439
Stud, 10-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
NU-2215
Hex Nut, 10-32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24