Service manual

The comms module plays no part in the cancelling mode of operation but it is used to select the

additive mode via section A of invertor IC37 and section A of NAND gate IC36. These gates

form a bi-stable flip flop which is triggered by the solo add switch SW26 and capacitor C181.

When additive mode is active section B of IC36 holds the solo clear line low via diode D66. This

shorts out any clear pulses and eliminates the cancelling action. When the solo add mode is

switched off capacitor C182 creates a negative going pulse which is inverted by section B of IC37

and fed on to the solo clear line via diode D67 which cancels all active solos.

Any solo on the console will set the solo on line high when it is active. Section C of invertor IC37

and transistors Q8 and Q9 sense this line and illuminate the lamp in switch SW27 if a solo is on. If

the solo clear switch SW27 is pressed it triggers a mono-stable flip flop formed by section E and

F of IC37 and section C of IC36. This temporarily overrides the additive mode via section B of

IC36 and produces a pulse on the clear line via section B of IC37 which cancels all active solos.

The 8 automute master switches are formed by the NAND gates IC30, IC31, IC32 and IC33.

These gates form bi-stable flip flops which are triggered by switches SW18, SW19, SW20,

SW21, SW22, SW23, SW24 and SW25 and capacitors C147, C150, C153, C156, C159, C162,

C165 and C168. The outputs from these flip flops are fed via passive lo pass filters to ideal diode

buffer amplifiers formed by amplifiers IC34 and IC35. These provide a low impedance drive onto

the automute busses but allow diode or action to take place when consoles are linked.

10. Matrix Module.

The matrix module houses the group to matrix level controls, the matrix insert and main outputs

as well as the stereo aux output master controls.

The pre and post fader audio group signals are received via the edge connector SK3. CMOS

switches IC16, IC18, IC20, IC21, IC22, IC24, IC25 and IC26 select pre or post fade signals to

feed the matrix. This selection is controlled by the global pre on switch SW4 and transistors Q2

and Q3. All signals are buffered by amplifiers IC17, IC19, IC23 and IC24 and fed to the matrix

bus and summing amplifiers via level control potentiometers RV6 to RV37.

Matrix bus inject signals are fed via T filters in the frame to differential amplifiers IC9 and IC15.

Pre-set VR6 and VR9 provide CMR adjustment and capacitors C42, C43, C44, C45, C69, C70,

C71 and C72 provide additional high frequency filtering; C46, C47, C73 and C74 provide AC

coupling.

Inputs from the master module (pre fader) are buffered by amplifier IC11 and fed to the matrix

busses via potentiometers RV2 to RV5. The matrix busses are virtual earth types which are

summed by amplifiers IC10 and IC13. Capacitors C52 and C53 provide AC coupling and capaci-

tor/resistor networks C50, C54, R82 and R91 ensure maximum stability and high frequency

rejection at all gains.

The summed matrix signals are fed to the insert send circuits formed by differential output ampli-

fiers IC12 and IC14. Output symmetry is adjusted by pre-sets VR7 and VR8 while high frequency

stability into any load is assured by filter capacitors C58, C59, C60, C62, C64, C65, C66 and

C68. Further filtering is achieved by T filters in the console frame and AC coupling is via C57,

C61, C63 and C67.

The insert return circuits are fed via T filters in the frame to the differential amplifiers IC28 and