REVISION C
BMX SERIES III CONSOLE
74
PACIFIC RESEARCH & ENGINEERING
amplifier U1A. The output of the INPUT MODE switch is also routed to the AUTO-CUE FUNCTION
header, and relays K5 and K6.
The SOLO bus input is summed by amplifier U2A and inverted by U3A. The output is connected to
the SOLO METER output terminal, and to SOLO relay K2 in the monitor section.
The CUE bus input is summed by amplifier U5A and inverted by U6A. The output is connected to the
CUE METER output terminal and AUTO-CUE FUNCTION header U7. The output of U6A is also
routed through the front panel CUE level control, mute relay K9, and output buffer amplifier U10A.
The 6 dB loss of the Talkback insert circuit is made up by the 6 dB gain of the buffer amplifier.
The headphone signal from AUTO-CUE relays K5 and K6 is routed through Talkback insert relay K7
and the HEADPHONE level control, to plug-in amplifier assembly A2. The line amplifier operates
at a fixed gain of 12 dB.
The Talkback to Control Room bus signal is summed by U8A and inverted by U8B. The output of U8B
is connected to the TALKBACK OUTPUT terminal, to Talkback insert relays K1 and K7, and to the
TALKBACK level control. The output of the TALKBACK control is routed to Talk to CUE relay K8A,
Talkback mute relay K8B, and output buffer amplifier U9. This buffer operates at unity gain, as supplied
by the factory. The gain of this stage may be increased to 6 dB with the installation of R61 and C44
as shown in the schematic.
LOGIC
The Control Room monitor system may be muted by a low applied to the MUTE CR logic bus or by
a low applied to the REMOTE MUTE CR input line. In either case, the low command causes a high
output on gate U200A. This high signal is routed to monitor mute relay K4, MUTE OUTPUT transistor
Q200, and through inverter U201F to warning lamp driver circuit Q201 and Q202.
The Control Room monitor system may be dimmed by a low applied to the DIM CR logic bus or by
a low applied to the REMOTE DIM CR input line. In either case, the low command causes a high output
on gate U200D. This high is routed through gate U202D to dim relay K3, and to DIM OUTPUT
transistor Q203.
The TALK CR bus is driven low whenever a Microphone Input Module, or the External input to the
Slate/Talkback/Test Oscillator Module, initiates communication to the Control Room. This low is
routed through gate U202B and inverter U201B to Talk to headphone relay K7. This low may also be
applied to Talk to CUE relay K8A by closing internal option switch S200-1, and to Talk to direct relay
K1 by closing switch S200-3.
The Talk to Control Room command may also be set to dim the Control Room monitor system by
closing switch S200-2, which directs the high output of U201B to monitor dim relay K3.
The Control Room monitors are automatically dimmed whenever the console initiates Talkback to
another location. This low dim command comes into the monitor module on the DIM CR bus. This