Model 78 and 78-1
Technical Manual
Section 4
Ludlum Measurements, Inc.
Page 4-4
March 2021
OVL (Detector Overload)
: a multi-turn potentiometer (approximately 20 revolutions) that
adjusts the detector current level, which must be exceeded to initiate an
OVERLOAD
alarm.
This control adjusts the current level discrimination point from 0.5 and 40 microamperes,
corresponding to the specific detector saturation point. The Cal/Switch board also utilizes a
16-position rotary switch (
FUNCTION
) to select the 16 setup parameters. (Refer to schematics
and component layout drawing near the end of the manual.) All of the setup parameters are
stored in the non-volatile EEPROM, which will retain data even after the Model 78 batteries
are removed. Changing parameters and information on switchboard controls, other than
those detailed above, are covered in Section 8 of this manual.
