Mackie d8b v3, Service Manual

Page: 26 / 117

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 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.
SIGNAL BACKPLANE BACKPLANE DESCRIPTION
NAME CONNECTION IN/OUTS
MUTE J23, PINS 12+51 J15, PIN 1 To CODEC board (J15, Pin 1)
To TAPE CARDS (J22, J20, J19, all pins 12+51)
RESET J23, PINS 13+50 J24, PIN 29 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 50)
To FX CARDS (J17, J14, J16 and J51,
all on pins 6+57)
UNMUTE J23, PINS 14+49 J24, PIN 27 From DSP board
NOTE that RESET is known as M_RESET on the DSP board. It simply changes name at the connec-
tors J24 and J21.
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.)
MUTE