Casella CEL CEL-393 - Manual (Page 79)

At switch on, the CEL-393 will always default to a standard set of
operating conditions pending receipt of operator instructions to the
contrary. These conditions are: battery check mode for approximately 25
seconds from switch on, after which the instrument goes to the 70dB
range with the period time set to 9999 minutes (infinite period giving
event mode storage).
The clock will assume 00.00 hours, and will thereby indicate elapsed
time until set to real time. There is no default for the delay start time
register, but its flag is set OFF.
The filter switch should be in the Off position on power up, and when
filters are selected, the instrument will default to the 1kHz band and
increment +ve (to higher frequencies) when the A key is operated.
Unless specified differently on purchase, the instrument will be provided
with L
10 , L 50 and L 90 as the statistical L n parameters.
8 CALIBRATION PROCEDURE
8.1 Introduction
Each instrument is carefully calibrated and inspected at our factory prior
to despatch. This is a complex procedure that is governed by verification
rules and international standards.
It is recommended that the instrument calibration be verified (preferably
annually but at least biannually) by a competant calibration laboratory.
393 Handbook /75.