Toa VX-2000SF - 4. SPEAKER LINE FAILURE DETECTION METHODS

Chapter 3: SYSTEM OPERATION OUTLINE
4. SPEAKER LINE FAILURE DETECTION METHODS
3-6
4. 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.
4.1. Impedance Detection Method
The VX-200SZ Impedance Detection module compares impedances to detect speaker line failures. A 40Hz
pilot signal for impedance detection is superimposed on the signal line. The VX-200SZ checks the impedance
before the [SP OUT] terminal, and compares it with the initially set impedance to detect speaker line failures.
The VX-200SZ module's initial impedance value must be set at the time of installation or during periodic service
maintenance.
Refer to
p. 10-10 for the initialisation method.
[VX-200SZ Failure detection]
[VX-200SP Failure detection]
VX-2000SF
VX-200SZ
Ground fault
detection
Short/open circuit detection
through impedance detection
SP OUT
PA IN
PA LINK
40 Hz
Pilot Tone
VX-2000SF
VX-200SP
Ground fault
detection
Short/open circuit
detection
SP OUT
LINE MONITOR
End of line
PA IN
PA LINK
20 kHz
Pilot Tone
4.2. Pilot Tone Detection Method
The VX-200SP Pilot Tone Detection module detects speaker line failures by using a pilot tone. A 20kHz failure
detection pilot signal is superimposed on the signal line. To detect speaker line failures, the VX-200SP checks
the signal return from the speaker line end to the LINE MONITOR terminal.