Toa VX-200SZ-2 - Manual (Page 9)

9
5. SPEAKEr LINE FAILUrE DETECTION METHODS
Note
The failure detection functions described here are designed to perform on a 100-volt line of speaker. For the
methods using a 70- or 50-volt line, please consult your TOA dealer.
[VX-200SP-2 Failure detection]
VX-2000SF
VX-200SP-2
SP OUT
LINE MONITOR
Shield
PA IN
PA LINK
20 kHz
Pilot Tone
40 Hz
Pilot Tone
Ground fault
detection
Detector
End-of-line unit
Short/open circuit
detection
5.1. Pilot Tone Detection Method
The VX-200SP-2 Pilot Tone Detection module detects speaker line failures by using a pilot tone.
A 20 kHz failure detection pilot signal is superimposed on the signal line. To detect speaker line failures, the
VX-200SP-2 module is used with the supplied End-of-line (EOL) unit in combination. The module's Detector
circuit controls the pilot tone detection by monitoring the terminated resistance value of the EOL unit, bringing
the same result as brought in the way that the VX-200SP checks the signal return from the speaker line end.