Thermal Compensation - GE SCB2000 Technical Service Manual

85% of 32 seconds. The upper rear halogen lamp
will cycle off just prior to the upper front.

Thermal Compensation

Note: Thermal compensation only occurs during
speedcook operation (preselect menu item). In
other words, when cooking with manual cook,
thermal compensation does not occur. When
using speedcook, you are selecting preselected
items from a menu. These items require
compensation for accurate and consistent cooking
results.
When cooking several food items consecutively,
the temperature in the oven's interior can become
very hot. The Advantium speedcooking program
(smart board) automatically compensates for the
increased temperature by adjusting the cooking
power levels of the upper and/or lower halogen
lamps. This innovative technology gives you oven-
quality food with consistent results.
Located inside of the oven cavity (upper right rear)
is a thermistor. At the start of each new
speedcooking operation (just prior to voltage
compensation occurring), the cavity thermistor
reads the oven cavity temperature. Depending
upon the oven cavity temperature and the amount
of cooking time selected, the smart board will
adjust the power level of the upper and/or the
lower halogen lamps to compensate for the
additional heat that may already exist in the oven
cavity (if previous cooking occurred).
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CN6 APPROX. 219 K
3
The oven cavity thermistor has a negative
temperature coefficient. In other words, as the
temperature of the thermistor probe increases, the
resistance of the thermistor decreases. This
resistance changes rapidly with small changes in
temperature. In fact, you can squeeze the
thermistor and see the resistance change fairly
quickly. At room temperature, the thermistor
should read approximately 200K to 250K ohms.
Thermal compensation can affect the upper
halogen lamps power level, the lower halogen
lamp power level, or both the upper and lower
halogen power levels simultaneously. Thermal
compensation can lower the upper halogen pair
by 1, 2, or 3 power levels. The lower halogen lamp
can also be reduced by 1, 2, or 3 power levels, but
never independently of the top halogen lamp pair.
In other words, thermal compensation on the
lower lamp will never be greater than the
compensation occurring on the top lamps. It is
possible, however, to have thermal compensation
occurring on the upper halogen lamp pair, but not
on the lower lamp.
Neither the upper halogen lamp pair nor the lower
halogen lamp can be compensated below power
levels of 2. In other words, if a power level of 3 is
selected for either the upper halogen pair or the
lower halogen lamp, then thermal compensation
can only reduce the power level by a maximum of
1 power level.
Thermal compensation only occurs when oven
cavity temperatures are higher than normal from
the previous cooking operation. When thermal
compensation is required, it will occur immediately
upon the start of a new speedcook operation (just
prior to voltage compensation occurring) and
GEA00439
there will be no indication in the display that
thermal compensation has occurred. The amount
of thermal compensation (1, 2, or 3 power levels)
depends upon the temperature of the oven cavity
at the start of the speedcook operation and the
amount of time selected.
When thermal compensation occurs, it is not
possible to see the adjusted power levels in the
display. If you were to press the power level pad
during a speedcook operation in which thermal
compensation occurred, you would not see the
adjusted power levels in the display. In fact, what
you would see is the original power level setting.
However, you can visually see compensation
@ ROOM TEMP.
occurring by carefully observing the cycling of the
halogen lamps.
GEA00400
WARNING: When viewing the halogen lamps, do
not stare directly into the face of the door window.
View the oven interior from a distance far enough
not to cause eye strain.
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