Kurzweil K2000 - K2000 Audio;Power Board Theory - Part 13

SECTION 5
AUDPWR6.DOC 12/22/92
RVB OVFLO is produced by the LSI chip to indicate whenm the internal digital signal levels are
too-great. Flip-flop U60-9 (8-4) latches this pulsed signal until the mocriprocessor can
recognize it. After recognition, the microprocessor resets the flip-flop.
Proper timing writes into the microcode RAM are critical and are synchronized with microprocessor
operation by several signals and circuits. The LSI chip actually controls the exact timing of
the write via the RVB MCA and RVB MCO busses while the former is the actual Write Enable signal
to the microcode RAM.- Counters U2l and U23 (8-1 to 8-3) are also involved in sequential address
generation/
RVB MUTE is produced by the Effects Microprocessor from power-up until the Microcode RAM is
initialized. The muting function is implemented at 8-6 on schematic page 4 by overriding the
effects unit output amplifier control voltage via R1S and 01 (8-6 of page 4). When RVB MUTE is
high, the U32-3 (8-6 on page 4) node is pulled high regardless of CACl OUT and passed to U32-l
which is the control voltage to US. Since the voltage-controlled amplIfiers attenuate for
increasing control voltage, US is effectively cut off until the microcode RAM can be initialized.
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