NOYAFA NF-838 - Manual (Page 13)

Other functions
(1) Low-voltage hint function
When the battery voltage is low, the low-voltage hint sign“ ”on LCD
will flash and the user shall have the battery replaced at this moment.
(2) Earphone function
The earphone can be used in noisy environment for operation so as to
avoid external interference.
(3) Volume adjustment function
Turn “volume” switch on the receiver when tracing cable to adjust.
(4) Floodlight function
The floodlight can be started at night or in darkness environment.
The floodlight turns on so as to facilitate your normal operation.
(5) Keypad sound start and stop function
If the user needs to stop keypad sound in test,the user can slightly
touch “wire sorting” and hunting key, the keypad sound is stopped;
if the keypad sound is about to started again, the operations above
shall be repeated so that the keypad sound is started.
Your excellent helper in cable test! 09