Casella CEL CEL-296 - Manual (Page 21)

No functions are performed in the "Off' position, except that any
spectra stored in the autoscan memory locations are retained,
provided the batteries are not removed (or an auxiliary power supply
disconnected).
When this switch is moved from the "Off' position to apply power to
the instrument, the microprocessor performs a self checking
procedure.
The start up message "CEL" will appear on the display while some
of the arrow markers may also be shown to indicate which of the
store locations contain octave data. Shortly afterwards the message
changes to "CEL 296" while arrows may appear on the display to
show which store locations contain third octave data. When this test
has been satisfactorily completed, all analysis and band switching
functions become available. Should the instrument fail the self test,
the "Err ALL" error message will be displayed.
Normally when the filter set is used with CEL sound level meters,
(except for the CEL-493/3,/2N, or /2 which have a 100 dB dynamic
range), the CEL-296/3 RANGE switch is set to "Hi" so that the upper
75 dB of its dynamic range is brought into operation.
When used with the CEL-493/3/, 2N, or /2 Sound Level Meters, set
the filter set RANGE switch to the following settings for frequency
analysis:
Level within CEL-493 CEL-296
Freq. Band Range Setting Range Setting
Less than 40 dB Lo Lo
Between 40 and 80 Lo Lo or Hi
More than 70 dB Med Hi
More than 120 dB Hi Hi
If both instruments are set to Lo range, an overload will be indicated
whenever the linear path (all pass) signal exceeds 80 dB, (refer to
Figure 5). Should such an overload occur, move the filter set
RANGE switch to "Hi' and use the top 75 dB of its range.
CEL Instruments Ltd CEL-296/3 Operator Handbook Page 21