Setting of key protection switch function

The key protection switch is in the bottom part of the Sound Level Meter (LA-1240/1250/1350/4350) to prevent incorrect setting of measurement conditions.

When you turn ON the key protection mode, you can only operate panel switches of [Lp/Leq…(Lx)], [START], [PAUSE], [CAL], [PRINT], and [STORE] shown in the following figure.

Procedure of changing key protection mode

When you set the key protection switch to the right position (a key symbol is printed), the key protection mode is entered. When you set it to the left position, the key protection mode is cancelled. In the key protection mode, a key protection symbol appears on the LCD.