Mackie Digital 8-Bus Service Manual page 26

MUTE and UNMUTE
On the clock card, there is an important Mute/Unmute circuit. It could have been fitted to any board,
but it just so happens it was placed on the clock card. Here is the circuit:
The left column of the table below shows the signals on the CLOCK card. This plugs into the
BACKPLANE card connector J23. The traces on the BACKPLANE lead to it's various inputs and output
connectors such as ribbon connector J15 to CODEC, J24 and J21 to DSP, card connectors J22, J20, J19
etc.)
SIGNAL
NAME
MUTE
RESET
UNMUTE
NOTE that RESET is known as M_RESET on the DSP board. It simply changes name at the connec-
tors J24 and J21.
26
MUTE
BACKPLANE BACKPLANE
CONNECTION IN/OUTS
J23, PINS 12+51 J15, PIN 1
J23, PINS 13+50 J24, PIN 29
J23, PINS 14+49 J24, PIN 27
The UNMUTE and RESET signals come from the DSP
board.
The MUTE signal will mute the D/A converters
(CS4390 pins 15 and 16) on the CODEC board and
the Tape Cards.
DESCRIPTION
To CODEC board (J15, Pin 1)
To TAPE CARDS (J22, J20, J19, all pins 12+51)
From DSP board (J24, pin 29, and J21, pin 7)
To CODEC board (J15, pin 3)
To TAPE CARDS, EXTRA and DIG IO
(J22, J20, J19, J18 and J30 all pins13+50)
To FX CARDS (J17, J14, J16 and J51,
all on pins 6+57)
From DSP board