17
OTHER MATTERS
Diode OR gate D4 and D5 drive comparator U2A, whose output goes low whenever
SOLO-CNTL-IP
or
SOLO-CNTL-OP
is high. U2A’s active low output drives the
LCR-MUTE
line,
which controls shunt-series analog switches U1209A, U1209B, U1209C, and U1209D.
Q2 operates as a 25 mA current source for the Rude Solo Light (RSL). Diode OR gate D6,
D7 and D11 link both oscillators (U1A and U1B) to comparator U2D whose output drives
transistor Q3 which shorts and unshorts the RSL, causing it to flash. Note that the RSL is
out-of-phase with the solo LEDs at any of the solo switches; that is, they alternate. D11
couples the
LCR-MUTE
line to U2D, ensuring that the RSL is extinguished when nothing is
soloed (the resting state for U1A and U1B is low, which would allow the RSL to be on).
D8 couples the
IP-SOLO
line to the input to the
SOLO-CNTL-OP
comparators. Since U1D
acts as a current-sink, it (via D8) prevents the output solo comparators from functioning
any time that
SOLO-CNTL-OP
is present. This means that inputs have precedence over
outputs in the solo system; if an output is soloed, and the user solos any input, that input
will be heard, and the output solo muted. The corresponding output solo LED is
extinguished during this time.
