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IGNORE SWITCH (Rev 6 PCB)
If the SR40·8 shares the intercom line with the lighting company, there is a high degree of
activity on the line, which would ordinarily be distracting to the mix engineer. The ignore
switch isolates the SR40·8 from the intercom line, while still allowing it to be accessible.
When the IGNORE switch, SW1802, has been depressed, analog switch U1801B opens,
disconnecting the headphone system from the intercom receive audio. When a call
signal comes in, U18.4 goes low, which closes analog switch U1801C, re-connecting the
receive audio from the intercom to the headphone system in the SR40·8. During the time
that the call lamp is lit, the console operator is connected to the intercom system again
(assuming that they’re wearing the headphones).
Answering the call by pressing the INTERCOM switch charges C144 via D1806, closing
analog switch U1801.8, temporarily defeating the effect of pressing the IGNORE switch for
a time determined by the discharge of C144 through R1899. Double-clicking the ignore
switch quickly discharges C144 through R1832, resetting the ignore state.
The ignore LED monitors the state of the ignore timer (C144 and R1899) via analog switch
U1801.16 and Q1807.
IGNORE SWITCH (Rev A and higher PCBs)
If the SR40·8 shares the intercom line with the lighting company, there is a high degree of
activity on the line, which would ordinarily be distracting to the mix engineer. The ignore
switch isolates the SR40·8 from the intercom line, while still allowing it to be accessible.
When the IGNORE switch, SW1802, has been depressed, analog switch U1801B opens,
disconnecting the headphone system from the intercom receive audio. When a call
signal comes in, U18.4 goes low, which closes analog switch U1801C, re-connecting the
receive audio from the intercom to the headphone system in the SR40·8. During the time
that the call lamp is lit, the console operator is connected to the intercom system again
(assuming that they’re wearing the headphones).
Answering the call by pressing the INTERCOM switch charges C144 via D1806, closing
analog switch U1801.8, temporarily defeating the effect of pressing the IGNORE switch for
a time determined by the discharge of C144 through R1899. Double-clicking the ignore
switch quickly discharges C144 through R1832, resetting the ignore state. Another
comparator section monitors the state of the ignore timer (C144 and R1899) and drives
the ignore LED D1803.
