The scheme for switching on the sound signal is shown in fig. 7-33.
Pic. 7-33. Sound signal switching circuit:
1 - socket for a portable lamp; 2 - sound signal; 3 - sound signal switch; 4 - fuse block.
If the signal strength decreases or wheezing appears, adjust the signal by turning the screw on its body in one direction or another until a loud and clear sound is obtained.
If the signal does not turn on, then check the reliability of the wire connection and the condition of the switch contacts.