SoundCraft User Guide

 Series 400B
User Manual
Soundcraft Electronics Ltd.
Unit 2, Borehamwood Industrial Park,
Rowley Lane,
Borehamwood, Herts.
Tel: 01-207-5050.
Telex: 21198
Facsimile:
WD6 5PZ England.
01-207-0194
Soundcraft Canada Inc.
1444, Hymus Blvd.
Dorval,
Quebec. Canada. HIP 1J6.
Tel: (514) 685 1610.
Telex: 05 822582.
Facsimile: (514) 685 2094
Soundcraft Electronics USA.
1517, 20th Street,
Santa Monica,
California. 90404.
Tel: (213) 4534591
Telex: 664923.
Facsimile: (213) 453 5634.
Soundcraft Japan
4F Yoyogi Living,
12-21 Sendagaya 5,
Shibuyaku, Tokyo, 151 Japan.
Tel: (03) 341 6201.
Facsimile: (03) 341 5260
The information in this document has been carefully checked and is
believed to be entirely reliable.
for inaccuracies.
However,
Furthermore, Soundcraft reserves the right to make
changes to any products herein to improve reliability,
no responsibility is assumed
function or design.
Soundcraft does not assume any liability arising out of the application or
use of any product or circuit described herein.
1.00
2.00
2.01
2.02
2.03
2.04
2.05
2.05
2.06
2.07
2.08
2.09
2.10
2.11
3.00
3.01
3.02
3.03
3.04
(b)
SERIES 400B
CONTENT
SERIAL NO. AND CONSOLE SPECIFICATION
CONSOLE DESCRIPTION
Generai Description
4001 Standard Input Module
4002 Standard Output Module
4005 Standard Master Module
4003 Monitor Input Module
4009 Stereo Input Module
4004 Monitor Output Module
4008 Monitor Master Module
4006 Effects Return Module
Input Connector Panel
Standard Output Connector Panel
Monitor Output Connector Panel
INSTALLATION
Applying Power
Interface Levels (Standard Console)
Connector Conventions
General Wiring Procedures
PAGE
10
13
14
15
16
17
18
19
19
19
20
20
4.00
4.01
4.02
4.03
4,04
4.05
5.00
6.00
6.01
6.02
6.03
6.04
6.05
7.00
8.00
9.00
OPERATION: STANDARD CONSOLE
Introduction
Record Mode
Multitrack Playback
Overdubbing
Remix Mode
OPERATION: MONITOR CONSOLE
MAINTENANCE
General Fault Finding
Removing Modules
Meter Alignment
Lamp Replacement
Power Supply Servicing
RECOMMENDED SPARES KIT
WARRANTY
SCHEMATICS
24
24
24
27
27
29
30
31
31
32
32
33
33
34
1.00
Model No. 0000000000000000000000000000000 ..........
Serial No. o0000000.0000000 0000000000000000000000000
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PROGRESS
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Assembled/Wired by .......esessccao ........
First Test By 0000000000000000000002000000000000 .
Final Test By «..e..oncccocccao .00.0000000000000000
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EQUIPPED WITH
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Output Modules .......osces 00.0... ....
Other Modules ......econcoccoccoco ........>.>....
P.S.U. 00000000000000000040000000000 .........>.. ..
OPTIONS - SPECIFY
ALTERATIONS TO SPEC.
SPECIAL INSTRUCTIONS
_
DESPATCH REQUIRED
Page 1
SERIES 400B
FRAME SIZE 00000400000000000000000000000088
PSU Serial No. ....... 00000000000020088 ..... AS Used in
final test
Works Order NO. ...cscsm.o. оооооооовааее
МАМЕ DATE SUPERVISORS
INSPECTION
TYPE QUANTITY ISSUE
2.00
2.01
Page 2
(SERIES 400B CONSOLE DESCRIPTION)
General Description
The series 400B is a fully modular 4 - bus mixing console and is available in
two specifications both available in 24/4/2 and 16/4/2 formats.
Standard
Module types:
4001 Standard Input
4002 Standard Output
4005 Standard Master
4006 Effects Return
Meter Display:
4 VU meters reading outputs 1-4 individually switchable to read 5-
8 plus 2VU meters for monitor source (mix/2 track replay/solos)
N.B.: An option is available for 4 extra VU meters.
Monitor
Module types:
4003 Monitor Input
4004 Monitor Output
4008 Monitor Master
4006 Monitor return
Meter Display:
8VU meters for monitor outputs, 2 VU meters for monitor source
(mix/2 track reply/solos)
Power Supply
For both specifications power is supplied from external unit supplying
+17V/-17V/+48V.
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4001
STANDARD INPUT
MODULE
2.02 4001 STANDARD INPUT MODULE
1.
2.
CHANNEL INPUT SECTION
The channel can be operated in either the microphone or line input modes.
The microphone input is an electronically balanced, transformerless design,
configured for optimum low noise performance. Electronic balancing
reduces the degradation of signal quality which is introduced by the more
normal transformer coupled designs, and endures superior transient
response, minimal phase shift, and excellent common mode rejection, even
with high frequence interference. The input impedance is greater than
2kOhms, which will not cause any loading effects on any normally used
studio microphone. The high level line Input is electronically balanced,
with an input-impedance of greater than 10kOhms which is high enough
to interface to any normal professional peripheral equipmment, without
loading the source.
a) Pad
Depressing the PAD button inserts a 20dB attenuator Into the input
of the microphone amplifier, and allows extremely high level input
signals to be catered for, without overloading the input stage. Such
high level signals can easily occur from high output capacitor
microphones used in close proximity to musical instruments. Direct
injection boxes are also capable of providing high signal levels.
b) LI (Line Input)
The high level input from a stereo type jack socket, is selected by
depressing the LI button. Tape returns should be replugged into
the line input sockets for mix down purposes.
с) Input Gain Trim
The microphone input can be varied between 20dB and 60dB of gain.
Used in conjunction with 20dB PAD, a 60dB control range is
available. The line level input can be varied between -10dB and 30dB
EQUALISER SECTION
The equaliser is an exceptionally versatile unit, allowing 5 areas of control
over the audio spectrum. All amplitude pots are centre detented for easy
zeroing.
a) / (High Pass Filter)
The high pass filter operates at 100Hz with an ultimate slope of
12dB/octave. This will effectively remove low frequency stage
rumble, and other extraneous signals.
b)
c)
d)
e)
f)
Page 4
HF (High Frequency)
15dB of boost or cut is available at 10kHz, with a "shelving"
characteristic, i.e., the slope of the EQ curve does not keep rising
with frequency, but having reached the desired amount, flattens out
or "shelves" from that frequency on.
Hi Mid
The Hi Mid Frequency is continuously variable between 600Hz and
10kHz. 15dB of boost or cut is available. The response is of the
"bell" type, i.e., having reached maximum amplitude (or minimum
in the case of cut) at the selected frequency, the amplitude response
returns to zero on either side of that frequency. The shape of the
curve, when plotted shows a characteristic "bell" shape. The Q of
the network (a measure of bandwidth) is 1.5.
Lo Mid
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The Lo Mid section is identical to the Hi Mid section, with the
exception that the frequency is variable between 150Hz and 2.4kHz.
LF (Low Frequency)
15dB of boost or cut is available at 60Hz, with a "shelving"
characteristic.
EQ
The equaliser circuitry can be switched in or out of the signal path,
independent of the high pass filter.
AUXILIARY SECTION
There are 4 auxiliary send controls available for use as echo, foldback or
other auxiliary effects units.
a)
b)
Sends 1 and 2
Auxiliary sends 1 and 2 are normally post fader, but can be switched
pre-fader. In both cases, they are post equaliser, insert point, and
channe! on/off switch.
Sends 3 and 4
Auxiliary sends 3 and 4 are permanently post-fader.
Page 5
ROUTING SECTION
The channel input signal can be routed to any or all of the 4 group Outputs
and the stereo Mix, by selecting the relevant routing button.
a)
b)
The Pan Pot is a centre detented control, with a loss of 4.5dB at
its centre point. This is a compromise between the 3dB loss required
for constant power panning, and 6dB loss required for constant
voltage panning.
Selection of any routing button assigns the channel signal to a pair
of output groups, or to the stero mix, via the pan pot.
CHANNEL STATUS SECTION
a)
b)
с)
d)
The channel "ON" status is indicated by a green LED. When a
channel is switched off, all auxiliary sends are also switched off,
with the exception of the signal to the insert jack.
PFL (Pre Fade Listen)
PFL soloes the pre-fader, post insert jack signal, independently of
the ON switch.
Peak
A red LED indicates the peak signal level at the insert send point.
It illuminates at a level of approximately 4dB below clipping.
Channel Fader
The channel fader has a slide length of 100mm and an exceptionally
smooth feel. Infinity cut off is greater than 90dB.
4002
STANDARD OUTPUT
MODULE
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4002 STANDARD OUTPUT MODULE
The 4002 Recording Output contains a group section and 2 tape return monitor
channels. The lower monitor section is used to monitor either its associated
group output, or one of the tape return tracks | to 4 depending on its position
in the console. The upper monitor section is used to monitor one of the tape
return tracks 5 to 8. Additionally, this section can also be used as a line level
input during remixing, with its signal panned into the main stereo mix.
1. MTR (METER SOURCE)
The signal that is fed to the meters is selected by this switch. In the
out position the meter is fed from the lower section and when depressed
is fed from the upper section.
NB An option is available to provide 4 extra meters enabling all 8
monitor sections to be shown simultaneously.
2. UPPER MONITOR SECTION (Tracks 5 - 8)
a) Tape Return
The tape return switch selects the monitor source between either
tape send (group output) or tape return (monitor input).
b) Vol
The monitor volume control enables the monitor contribution to the
stereo mix to be adjusted in level, to allow a satisfactory monitor
balance to be achieved during recording or playback of the multitrack
tape.
с) Auxiliary Sends 1 and 2
Auxiliary sends 1 and 2 are normally post-fader, but can be switched
pre-fader by selecting PRE. In both cases, the auxiliary signal is
derived after the monitor ON switch. These are used to provide
headphone mixes during recording and overdubbing.
d) Pan
The pan control allows the monitor signal to be panned to the
required position within the stereo mix.
e) PFL (Prefade Listen)
PFL the monitor channel signal independently of the Vol control.
3. LOWER MONITOR SECTION (Tracks 1 to 4)
The lower monitor section is similar in operation to the upper section,
and provides monitoring of tracks ! to 4.
Page 7
GROUP OUTPUT
Each group output controls the signal level to 2 tracks of the multitrack
recorder during the recording process i.e., group 1 will feed tracks | to
>, group 2 will feed tracks 2 to 6 etc. the group output signal is then
normally monitored by the relevant upper or lower monitor section.
2.04
Page 8
4005 STANDARD MASTER MODULE
This module contains the stereo output as well as the four unbalanced auxiliary
outputs.
It also contains the controls for the monitoring facilities and the talkback system.
1.
PHANTOM POWER
Capacitor microphones can be powered by the internal 48 Volt phantom
power supply by depressing the 'ON' button. This supplies power to all
mic inputs. Operation is indicated by a red LED.
N.B. When using direct injection boxes or unbalanced sources, the phantom
power supply should not be switched on.
Individual channel phantom power switching is available as an option.
AUXILIARY MASTERS 1-4
Each of the 4 auxiliary busses has an overall master level control. An
associated AFL (after fade listen) button allows the signal at the auxiliary
output to be monitored and metered.
OSCILLATOR
a) Frequency
The oscillator frequency can be changed between two set values of
700HZ when the button is 'out' and 10KHZ when the button is
depressed.
b) ON
Operation of this routes the oscillator signal to all the auxiliary
and group busses.
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Page 9
TALKBACK
a)
b)
с)
Input XLR
This provides the input point for a dynamic microphone.
Mic Level
The level of the talkback mic signal can be fully adjusted.
TB
Depressing this button routes the talkback signal to all aux and
group busses.
Monitor Section
a)
b)
c)
d)
REP
Depressing REP will monitor the electronically balanced 2 track
return.
MNO
To provide a compatibility check of the stereo signal, the left and
right monitor channels can be summed together by the MNO switch.
Monitor Level
The signal level to the headphones socket can be adjusted.
Phones/Pre Amp
The headphones output allows monitoring of the main stereo mix
output, also of any soloed signal. Depressing the button decreases
the signal by 8dB, to allow the use of an external power amplifier
to drive monitor loudspeakers.
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Page 10
2.05 4003 MONITOR INPUT
1.
CHANNEL INPUT SECTION
The Channel can be operated in either the microphone or line input modes.
The microphone input is an electronically balanced, transformerless design,
configured for optimum low noise performance. Electronic balancing
reduces the degradation of signal quality which is introduced by the more
normal transformer coupled designs, and ensures superior transient response,
minimal phase shift, and excellent common mode rejection, even at high
frequencies. This results in excellent immunity to Radio Frequency
interference. The input impedance is greater than 2KOhms which will
not cause any loading effects on any normally used studio microphone,
The high level line input is electronically balanced, with an input impedance
of greater than 10K ohms, which is high enough to interface to any normal
professional peripheral equipment, without loading the source.
a) PAD
Depressing the PAD button inserts a 20dB attenuator into the input
of the microphone amplifier, and allows extremely high level input
signals to be catered for, without overloading the input stage. Such
high level signals can easily occur from high output capacitor
microphones used in close proximity to musical instruments. Direct
injection boxes are also capable of providing high signal levels.
b) LI (Line Input)
The high level line input is selected by depressing the LI button,
with access via al/4 inch stereo jack on the rear panel.
с) Input Gain Trim
The microphone input can be varied between 20dB and 60dB of gain.
Used in conjunction with the 20dB PAD, a 60dB control range is
available,
The line input can be varied between -10dB and 30dB.
Page 11
EQUALISER SECTION
The equaliser is a versatile unit, allowing 5 areas of control to be exercised
over the audio spectrum. All amplitude pots are centre detented for easy
zeroing.
a)
b)
c)
d)
e)
f)
M (High Pass Filter)
The high pass filter operates at 100Hz with an ultimate slope of
12dB/Octave. This effectively removes low frequency stage rumble,
and other extraneous signals.
HF (High Frequency)
15dB of boost or cut is available at 100KHz, with a "shelving"
characteristic, i.e., the slope of the curve does not keep rising with
frequency, but having reached the desired amount, flattens out or
"shelves" from that frequency on.
Hi Mid
The Hi Mid Frequency is continuously variable between 600Hz and
10KHz. 15dB of boost cut is available. The response is of the
"bell" type, i.e., having reached maximum amplitude (or minimum
in the case of cut) at the selected frequency. The shape of the
curve, when plotted shows a characteristic "bell" shape. The Q of
the network (a measure of bandwidth) is 1.5.
Lo Mid
The Lo Mid section is identical to the Hi Mid section, with the
exception that the frequency is variable between 150Hz and 2.4KHz.
LF (Low Frequency)
15dB of boost or cut is available at 60Hz, with a "shelving"
characteristic.
EQ
The equaliser circuitry can be switched in or out of the signal path,
independent of the high pass filter.
3.
Page 12
MONITOR SECTION
a)
b)
с)
The 8 monitor sends are normally post the channel level control,
they can however be selected pre-fader. It is possible to select
sends 1-2 independently of 3-8 or vice versa. It is of course possible
to select all 8 as pre-fader.
The channel signal can be indpendently routed to the stereo mix
and panned between left and right.
The channel signal can be varied by the rotary channel fader.
CHANNEL STATUS SECTION
a)
b)
с)
ON
The channel "ON" mode is indicated by a green LED. When a
channel is switched off, all auxiliary sends are also switched off,
with the exception of the signal to the insert send jack.
PFL (Pre Fade Listen)
PFL soloes the pre-fader, post insert jack signal, independently of
the ON switch.
Peak
A red LED indicates the peak signal level at the output of the
equaliser. It illuminates at a level of 4dB below clipping.
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4009 STEREO INPUT MODULE
1.
2.
CHANNEL INPUT SECTION
The Channel can be operated using either Line Input A OR Line Input
B. Both Line Inputs are balanced, with an Input Impedance of greater
than 10kOhms, which is high enough to interface to any normal
professional peripheral equipment without loading the source.
a)
b)
с)
d)
B
Line Input B may be selected by pressing the button marked B.
(Phase)
Pressing the Phase button will invert the phase on the left-
hand input only to correct for any input mismatch.
Input Gain
The Input Gain can be varied between -12dB and +8dB of gain
using the Gain Trim control.
Г & К
i. With both these switches out the module works in stereo
mode.
il. With either L or R switched in, both channels of the
module are fed by either the left or right input.
iil. — With both switches depressed, both channels of the module
are fed by a mono sum of the left and right input.
EQUALISER SECTION
The Equaliser allows 3 areas of control over the audio spectrum. All
amplitude pots are centre detented for easy zeroing.
a)
b)
(High Pass Filter)
The High Pass Filter operates at 100Hz with an ultimate slope
of 12dB/Octave. This will effectively remove low frequency
stage rumble, and other extraneous signals.
HF (High Frequency)
15dB of boost or cut is available at 12kHz, with a "shelving"
characteristic, i.e. the slope of the EQ curve does not keep
rising with frequency, but having reached the desired amount,
flattens out or "shelves" from that frequency on.
3.
4.
с)
d)
LF (Low Frequency)
15dB of boost or cut is available at 60Hz, with a "shelving"
characteristic.
EQ
The Equaliser circuitry can be switched in and out of the signal
path, independant of the high pass filter.
AUXILIARY SECTION
There are 4 Auxiliary send controls available for use as echo, foldback
or other auxiliary effects units.
a)
b)
c)
Sends 1 and 2
Auxiliary sends 1 and 2 are normally post-fader, but can be
swtched Pre-fader by pressing the appropriate PRE button. In
both cases they are post equaliser. Auxiliaries 1 and 2 can be
selected mono or stereo and dependant/independant of the
channel mute by push-on links located on the PCB.
PRE
Auxiliary sends 1-2 may be routed Pre-fader by pressing the
PRE button.
Sends 3 and 4
Auxiliary sends 3 and 4 are permanently post-fader. Sends 3
and 4 can also be selected mono or stereo by push-on links.
ROUTING SECTION
The channel input signal may be routed to any of the pairs of Group
Outputs (1-2, 3-4) or the Stereo Mix, by selecting the relevant routing
button.
a)
b)
Balance
The balance control corrects or deliberately creates any errors
in stereo matching before the fader and the auxiliary sends.
Routing
Selection of any routing button assigns the channel signal to a
pair of output groups, or the stereo mix, via the balance
correction.
5.
CHANNEL STATUS SECTION
a)
b)
с)
Я)
ON
The channel "ON" status is indicated by a green LED. When
a channel is switched off the auxiliary sends 1 and 2 are not
necessarily cut and depend on the set up of the push-on links
(jumpers).
PFL
Pre-fade Listen Soloes the Pre-fader independently of the ON
switch. This gives a mono check of signal before the on/off
switch. PFL operation is indicated by a red LED on the channel,
and a master warning LED on the master module.
Peak
A red LED indicates the peak signal level. This gives visual
warning that the higher signal Right or Left is within 5dB of
clipping.
Channel Fader
The channel fader is an accurately matched stereo fader of
slide length 100mm and an exceptionally smooth feel. Infinity
cut off is greater than 90dB.
4004
MONITOR OUTPUT
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2.06 4004 MONITOR OUTPUT
The 4004 Monitor output is a double module, although physically the same width
as a single module, providing two totally independent outputs. The modules are
configured such that the lower sections provide outputs 1,3 5 and 7 while the
upper sections provide outputs 2,4,6 and 8. Each output is provided with its
own meter.
|. UPPER SECTION
a) SUB
This places the output of the volume pot into the stereo mix via
the pan pot.
b) AFL (After Fade Listen)
Group output signal can be soloed.
2. LOWER SECTION
The lower section is similar in operation to the upper.
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2.07 4008 MONITOR MASTER
This is similar in all operation with the exception that the auxiliary's are not
present on a monitor desk.
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Page 15
4006 EFFECTS RETURN MODULE
This module contains 4 identical sections for controlling signals from external
effects devices.
1. SECTION 1
a)
b)
с)
d)
e)
Auxiliary Sends 1 and 2
Auxiliary Sends land 2 are normally post-fader, but can be switched
pre-fader by selectign PRE. In both cases, the auxiliary signal is
derived after the ON switch.
PAN
The pan control allows the signal to be panned to the required
position within the stereo mix.
VOL
The volume control enables the contribution to the stereo mix to
be adjusted in level.
ON
The return channel and associated auxiliary sends are activated by
depressing the "ON" button. Operation is indicated by an adjacent
green LED.
PFL
The return signal can be soloed independent of the "ON" switch.
SECTIONS 2, 3 AND 4
These sections are similar in operation to section |.
2.09
Page 16
INPUT CONNECTOR PANEL
This panel is common on both standard and monitor consoles.
|.
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Line Inputs
These stereo standard jacks carry the balanced line inputs. They are
wired with the tip as signal high, the ring as signal low and the sleeve
as earth.
These connections are not normalled from the tape returns.
Mic Inputs
These carry the balanced microphone inputs. They are wired with pin 3
as signal high, pin 2 as signal low and pin 1 as earth.
They can be fed with +48V phantom power for capacitor microphones.
This is controlled by a master phantom switch on the master module.
N.B. The phantom power should not be turned on when an unbalanced
microphone or direct inject box is used.
Phantom Power Switching
In addition to the master phantom switch individual channel phantom
switches can be fitted as an option.
Channel Inserts
These stereo standard jacks carry both the insert send and insert return
signals. They are wired with the tip as insert return, the ring as insert
send and the sleeve as earth.
Under normal conditions with nothing inserted the signal is normalled
through by the jack socket and thus inserting a jack will automatically
break this link.
The Insert is post eq. but is before the channel! fader and is independent
of the channel on switch.
Multicore Fixing
This provides the facility to mount a 56 way Varelco connector which
would normally be wired to carry the microphone inputs.
PSU Connector
This provides the d.c. power to the console from the external power supply.
Please ensure cable connector is screwed fully in to alleviate any chance
of intermittent contact.
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Page 17
2.10 STANDARD OUTPUT CONNECTOR PANEL
|.
3.
5.
Tape Sends
These are fed direct from the group outputs. They are connected in pairs,
i.e. group 1 feeds tape sends | and 5 etc. These outputs are unbalanced
with pin 3 as signal.
Group Inserts
This is a stereo, standard break point jack socket which contains both
insert send and return. The socket is connected with the tip as insert
return and the ring as insert send. The sleeve is, of course, ground.
Under normal conditions i.e. with socket not in use the send is connected
to return by the socket such that inserting a jack automatically breaks
this link,
The insert point is before the group fader.
Mix Outputs
These sockets carry the main stereo outputs. These outputs are unbalanced
with pin 3 as the signal.
Mix Inserts
These are identical in form and operation to the group insert points.
Auxiliary Outputs
These are standard jack socket outputs for the auxiliary masters. These
outputs are unbalanced.
Effect Returns
These stereo standard jack sockets carry the balanced inputs for the
optional 4006 Effects Returns Module. These are wired with the tip as
the signal high, the ring as the signal low and the sleeve as earth.
2-Track Return
These stereo standard jacks carry the balanced 2-track returns. These
are wired with the tip as signal high, the ring as signal low and sleeve
as earth,
Tape Returns
These stereo standard jack sockets carry the balanced tape returns and
are wired with the tip as signal high, the ring as signal low and the sleeve
as earth,
4008 MONITOR OUTPUT
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2.11
Page 18
MONITOR OUTPUT CONNECTOR PANEL
|.
Group Sends
These are fed from the eight individual group outputs. The outputs are
unbalanced with pin 3 as the signal.
Group Inserts
This is a stereo, standard break point jack socket which contains both
insert send and return. The socket is connected with the tip as insert
return and the ring as insert send. The sleeve is, of course, ground.
Under normal conditions i.e. with the socket not in use the send is
connected to return by the socket such that inserting a jack automatically
breaks this link.
The insert point is before the group fader.
Mix Outputs
These sockets carry the main stereo outputs. These outputs are unbalanced
with pin 3 as the signal.
Mix Insert
These are identical in form and operation to the group insert points.
Effect Returns
These stereo standard jack sockets carry the balanced inputs for the
optional 4006 Effects Returns Module. These are wired with the tip as
“the signal high, the ring as the signal low and the sleeve as earth.
2-Track Return
These stereo standard jacks carry the balanced 2-track returns. These
are wired with the tip as signal high, the ring as signal low and sleeve
as earth,
3.00
3.01
3.02
Page 19
INSTALLATION
APPLYING POWER
Before switching on the series 400B check that the mains voltage selector on
the power unit is set at the correct mains voltage for your area, and that the
fuse is of the correct rating.
For operation on voltages between 220 and 240VAC, the fuse should be rated at
1.60 amps. 10mm Anti surge.
For operation on voltage between 100 and 120VAC, the fuse should be rated at
3.15amp, 20mm Anti surge,
Do not replace the fuse with any other type, as this could become a safety
hazard, and will void the warranty.
INTERFACE LEVELS (STANDARD CONSOLE)
The Series 400B is normally supplied to provide compatible level interfacing with
standard professionsal equipment i.e., +4dBr (ref 0.775v volt). However, provision
has been made to allow the user to modify the tape interface levels for use
with semi-professional equipment, operating at -10dBV (ref 1.00 Volt), or other
levels,
The change in tape interface operating level is accomplished by reducing the
console group output level by the required amount, and increasing the console
monitor return gain by an identical amount, and can be done by the addition of
1 resistor, the removal of a link and changing 4 resistors on each standard output
circuit board. -
Group Output Level
1. Cut track across rear of Rll.
2. Add resistor in position RXI. Recommended value is 750 ohms.
Monitor Return Gain
For interfacing to the normal Teac/Tascam operation level of -10dBV R14, 15,
31 and 32 should be changed to 22kOhms in value.
Auxiliary Outputs
Power amplifiers are often rated at 300mV sensitivity, for full output. In such
cases, an attenuator should be Installed at the input of the power amplifier, to
attenuate the +4dBr (1.228V) signal from the console, by approximately 10 to 15
dB. This can be achieved by using a 2.2kOhm series resistor, and a 680 ohm,
shunt resistor across the amplifier input.
3.03
3.04
Page 20
CONNECTOR CONVENTIONS
All XLR type connections are normally wired to the following standard
Pin | Signal Earth (Screen)
Pin 2 Signal Low
Pin 3 Signal High
On Series 400B all main outputs are unbalanced.
GENERAL WIRING PROCEDURES
To take full advantage of the excellent signal to noise ratio and low distortion
of Soundcraft consoles care must be taken to ensure that incorrect installation
and wiring does not degrade its performance. Hum, buzz, instability and Radio
Frequency Interference (RFI) can usually be traced to earth loops and inferior
earthing systems. In some areas, especially heavy industrial areas, the incoming
mains earth will not be adequate, and a separate technical earth for all the
audio equipment must be supplied. However, check with your local electricity
supply company to ensure that safety rgulations are not infringed or negated.
The successful, hum free, installation of a systems requires careful forethought,
and the establishment of a set of ground rules, which must be consistently
adhered to at all stages of the installation.
1. Initial Wiring Considerations
a) For optimum performance, it is essential for the earthing system
to be clean and noise free, as all signals are referenced to this
earth, A central point should be decided on for the main earth
point system, and all earths should be "Star fed" from this point. It
is common electrical practice to "daisy chain" the earths to all
electrical outlets but this method is unsuitable for audio installations.
The preferred method is to run an individual earth wire from each
outlet, back to the system star point to form the safety earth of
screen reference for each piece of equipment. A separate earth
wire should also be run from each equipment rack and area, to the
star point.. This may or may not be used depending on
circumstances, but it is easier to install in the first place, than
later, when problems arise.
The location of the star point should be a convenient, easily
accessible place preferably at the rear of the console, or in the
main equipment rack.
b) Install separate "clean" and "dirty" mains outlets, wired individually
back to the incoming mains distribution box. Use the "Clean" supply
for all audio equipment, and the "Dirty" supply for all lighting,
vending machines, etc. Never mix the two systems.
c) If necessary, to provide sufficient isolation from mains borne
interference, install an isolating transformer for the "clean" supply.
The isolation transformer should be provided with a Faraday Shield
which must be connected to earth.
Page 21
d) Never locate the incoming mains distribution box near audio
equipment, especially tape recorders, which are very sensitive to
electro-magnetic fields.
e) Ensure that all equipment racks are connected to earth, via a
separate wire back to the star point.
f) Equipment which has unbalanced inputs and outputs may need to
be isolated from the rack to prevent earth loops.
Audio Wiring
Having provided all equipment with power and earthing connections,
consideration must be given to the method of providing audio
interconnection, and adequate screening of those interconnections. This
must be done in a logical sequence to avoid problems, and assist in the
localisation of problemm equipment.
a) Connect Control Room Monitor system to the console, and check
for any hum, buzz,, or Radio Frequency Interference. Only when
you are satisfied with the quietness of the console and monitor
system should you proceed to the next step.
b) Connect multitrack tape recorder, via noise reduction system if
applicable, and again check that the system is still clean.
c) Connect stereo tape recorders, studio monitors, echo and foldback
sends, one at a time, checking and isolating any connection which
degrades performance.
d) Connect all peripheral effects devices.
e) Connect all microphone lines.
By following this sequence much time annd future trouble will be saved,
and the result will be a quiet, stable system.
Shielding
Audio equipment is supplied with a variety of input and output
configurations, which must be taken into consideration when deciding where
the screen connections should be made. There are three sources of
unwanted signal being impressed on the screen, which are as follows:-
i) Extraneous electrostatic or electromagnetic fields
ii) Noise and interference on the earth line
11) ~~ Capacitive coupling between the screen and the signal wires.
Page 22
To minimise the adverse affects of the unwanted coupling to the signal
wires, it is important that the screen is connected at one end only, i.e.,
the screen must not carry any signal current. Any signal on the wires
within the screen will be capacitively coupled to the screen, and this
current will ultimately be returned to the source of the signal, either
directly,, if the screen is connected at the signal source end, or indirectly
via the entire earthing system, if the screen is connected at the signal
destination end. The indirect connection will cause an increase in high
frequency cross talk, and should be avoided wherever possible. Therefore,
in general, always connect the shield only at the signal source end. In
high R.F. areas, the screen can also be connected to earth via a 0.01
micro farad capacitor. This will present a short circuit at R.F. frequencies,
thus lowering the effective shield impedance to ground. However,, at low
audio frequencies the reactance of the capacitor will be sufficiently high
to not cause an earth loop problem.
Combinations of unbalanced, balanced, and electronically balanced
(differential) systems mean that there are nine interconnection
permutations. The optimum of the screen in each case is shown on Table 1.
TABLE |
OUTPUT INPUT SCREEN
1) Unbalanced Unbalanced Source
2) Unbalanced Balanced Source
3) Unbalanced Differential Source
4) Balanced (Note 1) Unbalanced Destination
5) Balanced Balanced Source
6) Balanced (Note 2) Differential Destination
7) Differential (Note 3) Unbalanced Source
8) Differential Balanced Source
9) Differential Differential Source
NOTE 1 The shield is connected to the designation earth point, which
is opposite to normal practice, because the signal wires being
shielded are referenced to the input earth, not the output
earth.
NOTE 2 If the output transformer is centre tapped to earth, the
screen should be connected at the source.
NOTE 3 When an active differential output is operated in unbalanced
mode, it Is very important that the output current returns
to earth via the shortest, least reactive route. Check for
instability at the output.
Page 23
N.B. a) Install cases, use good quality twin screened audio cable.
Check for instability at the output.
b) Always connect both conductors at both ends, and ensure
that the screen is only connected at one end.
с) Do not disconnect the mains earth from each piece of
equipment, This is needed to provide both safety and screen
returns to the system star point.
d) Equipment which has unbalanced inputs and outputs may need
to be electrically isolated from the equipment rack and/or
other equipment, to avoid earth loops.
[t is important to remember that all equipment which is connected to the
mains is a potential source of hum and interference, and may radiate both
electrostatic or electromagnetic radiation. In addition, the mains will also
act as a carrier for many forms of R.F. interference generated by electric
motors, air-conditioning units, thyristor light dimmers etc. Unless the
earth system is clean, all attempts to improve hum noise levels will be
futile. In extreme cases there will be no alternative but to provide a
completely separate and independent "technical! earth" to replace the
incoming "noisy earth". However, always consult your local electricity
supply authority to ensure that safety regulations are not being infringed.
4.00
4.01
4.02
Page 24
OPERATION: RECORDING CONSOLE
INTRODUCTION
The Series 400B console, when fitted with standard input and standard output
modules has been designed to provide the varied facilities required in a modern 4
or 8 track recording studio.
The recording process can be broken down into 4 basic sequences:-
1.
2.
Record mode: Recording direct from microphone or line input on to the
multitrack tape recorder.
Multitrack Playback: listening to what has been recorded.
Overdubbing: Building up the track complement while listening to what
has already been recorded. Basically, this is a combination of one and two.
Mixing: Combining all the recorded tracks, various effects, echo etc. to
form the final stereo mix.
A detailed explanation of all controls and switches has been given in
section 2, and it is assumed that the user is familiar with basic multitrack
recording methods.
RECORD MODE
|.
Record Mode
This is the basic starting point in making a recording. Input channels are
placed in the microphone mode by placing the mic/line switch in the "up"
position, The signal is routed to the desired console group output by
depressing the relevant group routing button on each channel. The signal
can be routed to more than one group if desired and panned between any
odd and even numbered groups by using the channel pan pot.
The signal appearing at the console group output to the tape recorder can
now be metered on the relevant VU meter, if the tape return button is in
the "up" position. A monitor balance is achieved using the appropriate
monitor level control. The monitor pan pot will pan the signal between
left and right speakers.
The various gain and level controls throughout the signal chain may now
be adjusted to set the operating levels for optimum signal to noise ratio
and headroom conditions.
5.
Page 25
Channel and Group Faders
In general the channel and group faders should be set to approximately
the zero position. This will enable the engineer to increase the level by
10dB, or fade out completely, while normally operating in the fine resolution
area of the fader travel. The absolute position of the fader is not too
critical, but situations where for example, the channel fader is operated
at -30dB, with the associated group fader at +10dB should be avoided, as
this will degrade the normally excellent signal to noise ratio of the console.
Similarly, the opposite case runs the risk of distortion.
Microphone Gain
Having set both channel and group faders as above, the microphone gain
is set to give the required level at the group output. The amount of gain
required depends on the type of microphone, the sound pressure level
developed by the instrument or voice and the distance between the sound
source and microphone. In the case of high output and high sound pressure
levels, it may be necessary to switch in the -20dB attenuator pad, to
prevent overloading the input stage.
Insert Patch Points
In situations where the dynamics of the input signal are very wide or
unpredictable, or where a particular effect is required, it is often necessary
to patch in a limiter/compressor, equaliser or effects device into the signal
chain. This can be done either via the channel insert jack points or the
group insert jack points. Which insert point is used will depend on the
actual effect required. If only an individual instrument is to be controlled,
the channel insert point would be used. However, if a number of microphone
channels have been mixed to a single group, such as backing vocals for
instance, then it will be necessary to patch in an overall limiter, using
the group insert point.
Headphone Mix
During recording, it is of course essential for the musicians to hear what
they and everybody else are playing. Headphones mixes are derived using
any or all of auxiliary sends, either direct from the input channels, or
alternatively from the group monitor channels. Deriving the headphone
mix from the monitor channels has the advantage of giving the musicians
a mix when replaying the recording just made, which is useful when
overdubbing to enable them to hear their performance. However, a mix
derived from the monitor channels during recording will be affected by
any gain riding of the channel or group faders, which may cause problems.
This can be avoided by using the input channel auxiliary send | and 2,
switched to Pre. The headphone signal is thus derived from before the
channel fader, and is unaffected by any change in the position of that fader.
Echo Sends
Similarly to headphone mixes, echo sends may also be generated from
either the input channels or the monitor channels. However, unlike
headphone mixes the echo send is usually required to be derived after the
fader, so that it is proportional to the fader level. This ensures that the
percentage of direct signal to echo signal remains constant, regardless of
fader position. This condition is met on auxiliary sends 1 and 2, if Pre is
not selected, and also on sends 3 and 4.
The individual situation determines whether the echo send is derived from
the input channel or the monitor channel. Normally if the echo return
signal is to be recorded on the multitrack tape recorder, then the echo
send will be derived from the input channels. However, if it is an echo
mix for monitoring purposes only,, then it would be more relevant to use
the monitor channel sends to drive the echo send mix.
Echo Returns
The output of the echo or reverberation device, i.e., the echo return
signal, patched into either unused input channels if this signal is required
to go to tape, or alternatively patched into unused monitor channels if it
is only monitor echo and no input channels are available.
If an input channel is used, the return signal is patched into the line input
jack of the relevant channel. The channel must then be placed in the
line mode by depressing LI. Line gain and fader position can now be set
up as described for microphone inputs.
The echo return can now be routed to the stereo mix, or to the group
outputs if it is required to record the echo signal, by depressing mix or
any of the group routing buttons.
Naturally when an input channel is used as an echo return, the echo return
signal may also be sent to any of the auxiliary sends. This allows echo to
be added to the headphone mix if desired. It is also possible of course,
to send the echo return to the echo send and create a loop in the echo
system. When used with a reverbaration device the effect will be to
increase the reverberation time. When used with a tape delay, it will
create multiple delays, decaying in amplitude in a manner controlled by
the send and return levels. This effect must be handled with care. If
the echo send level from the echo return channel is set too high, the
entire system will start to feed back and go into oscillation, instead of
decreasing in amplitude with each successive loop.
If it is not required to record the echo signal, but merely to route it
direct to monitors select mix. This will route the signal directly to the
stereo mix buss, which is also the monitor signal in this mode.
4.03
4.04
Page 27
MULTITRACK PLAYBACK
Having actually recorded something on the multi-track recorder, it
is necessary to be able to listen to the recording. This is achieved
by simply selecting Tape Return. The effect of this is to connect
the individual group monitor to the output of the relevant track of
the multitrack recorder. Therefore the signal from the recorder
now follows the same monitor signal path as the group output signal
had been using. This means that all levels and panning, and therefore
the monitor mix, will remain the same as they were when the
recording was being mmade. This is assuming, of course, that the
tape machines are correctly aligned.
The facility of monitoring the playback of the multitrack in this
way enables the operator to perform a quality check even while
the recocrding is being made, providing that the following
precautions are observed.
i. Isolation between control room and studio is good. If not,
the musicians will hear a delayed version of what they are
playing.
2. Headphone mix is derived from the channel faders, otherwise
the musicians will again hear a delayed version.
3. Noise reduction system is either a simultaneous encode-decode
system, or not used. If it is not a simultaneous encode-
decode system, then while recording it will be in the encode
mode, and the signal presented to the console monitor return
will probably be the tape recorder line input signal i.e., the
signal from the console group output. In this case, depressing
Tape Return will appear to have no effect, as it will be the
same signal in both cases. This particular effect can in some
cases be put to good use, however, when overdubbing as it
allows the monitor switching to be achieved automatically,
depending on the mode of the tape recorder. This will be
dealt with more thoroughly in Section 4.04 which describes
the overdubbing process. |
OVERDUBBING
Overdubbing is the process of building up a recording track by track,
while listening to all the previously recorded trcks. As such it will
be clear that this is a combination of the previous two modes, with
some channels in the microphone (Recording) mode, and some
monitors in the Tape Return (Multi-track playback) mode.
Any tracks which have already been recorded are monitored by
selecting the relevant Tape Return buttons. A headphone mix may
be set up using the auxiliary sends on these monitor channels.
Monitor echo can also be similarly set up, as already described in
Section 4.02.
Page 28
At this stage, a decision must be made as to the source of the
headphone mix signal from the overdub channels. It can be derived
from either the input channel or the group monitor channel or both.
l.
Input Channel
In this case, the musian always hears himself. However he
will not be able to hear his previously recorded signal off
the tape recorder, if heneeds to "drop in" in the middle of
a take.
Monitor Channel
[f the headphone mix is derived from the monitor channels,
the engineer can decide whether the musician hears himself
live or the previously recorded signal off tape (syncplayback(,
by depressing the Tape Return button. However he will not
be able to hear both, and a vocalist for instance may find
it difficult to match levels, and intonation.
This switching can sometimes be achieved automatically if a
noise reduction unit is in use, and with some tape recorders.
If the tape recorder or noise reduction unit is arranged to
switch its sync output to line input whenever the tape recorder
is in stop, fast forward, rewind, or record and only switch
to sync playback off tape when the tape recorder is in the
play mode, the automatic switching condition will be met.
All that is now usually necessary when overdubbing is to
select Tape Return on the relevant monitor channel, and let
the tape reccorder and/or noise reduction system perform
the work of monitor switching.
The musician now hears himself live at all times except when
the tape recorder is actually in the sync play mode, when
he will hear his previous signal off tape. This method saves
the engineer from continually switching monitor sources, but
can only be used with certain tape recorders.
Both
If derived from both, then the musician is able to hear himself
live, via the input channel, and his previous recording via
the monitor channel, if it is switched to monitor Tape Return,
until the moment of entering the record mode. At that
point, most tape recorders switch fromm sync playback to
line input. The effect of this will be a slight increase in
the level of that signal in the headphone mix, due to the
addition of the input channel! signal and tape recorder line
input signal, which is effectively the same signal.
4.05
Page 29
REMIX MODE
When all recording and overdubbing has been completed, the console
is placed in the remix mode.
Remixing is the process of combining all the previously recorded
tracks together with any special effects devices such as harmonisers,
flangers and delay lines.
It is now necessary to replug the tape machine outputs into the
input module line input sockets. Any combination of inputs may
be used, not necessarily arranging track | to input 1, track 2 to
input 2 etc. Once there have been replugged, the monitor channels
may now be used at effects return channel by plugging the effects
device outputs into the tape return juck sockets. It is best to use
monitors 5 to 8 for this purpose, leaving monitors 1-4 to act as
subgroups. .-
The remix mode is entered by selecting line input on each input
channel (LI), which connects the output of the multitrack tape
recorder to the input of each channel, via the line trim control.
This is normally set approximately to the "0" position if the recorder
is operating at a nominal +4dB line level. However, like the mike
trim, it can be adjusted to allow the channel fader to work near
its nominal "0" position.
By selecting MIX, the channel can be routed directly to the stereo
mix, via the channel pan pot, to allow positioning of the signal
within the stereo perspective.
Alternatively the signal can be routed to any of the output groups
to enable the formation of sub groups, which can then be re-routed
back into the stereo mix.
Limiters or other effects devices can be connected to any channel
or output group by patch into the relevant insert points.
All 4 auxiliary sends can be used to feed echo or effects devices,
as headphones mixes are not required during remixing.
The composite stereo mix will be controlled in level by the stereo
master fader and the level metered on the stereo mix meters.
These meters will also indicate the level of any solo signal, or of
the stereo tape return selected on the 2 track replay (REP) button.
This allows quality and level checking of the stereo recording in
the same way as described for multitrack playback.
MICS
or DI'S
MIX SIDEFILL LEFT
OUTPUTS a
SIDEFILL RIGHT
`
/
2
| MONITOR
SPEAKERS
1/P CHANNELS GROUP 4
OUTPUTS 6
8
PHONES
0/P
POWER
AMPS
OPERATOR'S
MONITOR
5.00
Page 30
OPERATION: MONITOR CONSOLE
Monitor mixers are used as a convenient way of obtaining a number of
independently controllable mixes from one set of sound sources.
Typical applications for monitor mixers being:
a) providing on stage foldback for musicians
b) audio distribution in theatres, conferences, etc.
Taking case a) as a practical example, and referring to the diagram, all
instruments are connected to the mixer via microphones or direct injection (D.l.)
boxes, in the usual way. Each output would then be assigned to one or more
monitor loudspeaker on the stage.
e.g. Mix L + R of outputs might feed the sidefills, Groups 1 - 3, the musicians"
individual monitors.
Phones output feeds the mixer operator's monitor.
Sends 1 - 2 on the input module are PRE/POST fade selectable,
independently of sends 3 - 8, thus giving the system a high degree of flexibility.
If, for example, the mix outputs were to be used to make a stereo tape recording
of a performance, then sends 1 - 2 could feed the sidefills in the same way as
MIX, by being selected to POST fade.
Sends 3 - 8, set to pre fade, could then be used for the musicians.
The console could, in fact, be used as a main P.A. mixer, if necessary, using MIX
to drive the P.A. amps, and the groups for auxiliary and foldback functions.
6.00
6.01
Page 31
MAINTENANCE
Although all Soundcraft Consoles have been designed with long term reliability
in mind, it is inevitable that occasional maintenance will be required. However,
due to the amount of attention given to the problems of maintenance during the
design stages of this console, and the modular construction, servicing tends to
be extremely simple to carry out, with the minimumm of test equipment needed
to isolate and rectify faults.
GENERAL FAULT FINDING
With the exception of the electronically balanced microphone amplifier all signal
electronics are configured around high slew rate, low noise integrated circuits.
The microphone amplifier is a proprietory design utilizing a discrete transistor,
noise cancelling front end, differentially summed via a low noise integrated circuit.
The use of integrated circuits means that the majority of the audio faults can
be repaired by simply replacing the I.C., having first isolated the fault to be a
particular stage in the signal chain. The isolation can often be done without
even removing the module from the console, by judicious use of the insert points,
and/or switching the module to various modes. As with all servicing, a good
knowledge of the basic signal flow is necessary for the best results. Each module
should be viewed as a number of signal blocks, through which the signal must
flow. If the signal appears at the input to a block, but not at the output, then
the fault lies within that block. - By dividing a module into individual sections,
what a first appears to be an extremely complicated piece of equipment can be
simpliefied into a series of simple sequential stages. This is the basic first move
in all types of fault finding, and usually requires nothing more than a certain
amount of logical thought. Servicing a mixing console is more a matter of clear
thinking and having an understanding of what should be happening, than having
a highly developed technical knowledge.
To illustrate the method of logical finding, let us assume that we have a non
functioning input module, in both microphone and line modes.
The first step is to ensure that a fault really does exist. Check that the module
is in the correct mode of operation, and that no jacks are inserted in the insert
points, which may be interrupting the signal flow.
If in doubt about the module operation, set up an adjacent module in exactly
the same way, which will allow a direct comparison between a working and
possible non-working module.
Route the channel directly to mix, so that the channel may be monitored in the
normal way. Using an oscillator set to approximately 1kHz, patch the oscillator
signal into the channel line input. If all is well an undistorted signal should now
be heard. More likely, because of the fault, it won't.
Large sections of the module circuitry can be bypassed by switching out the Hi-
pas filter, and the Equaliser.
If switching out a section causes the signal to re-appear, then the fault is located
in that section, which can then be traced at component level, by removing the
module from the console frame, and reconnecting it via extender cables.
6.02
6.03
Page 32
With the module installed on extender cables, access is now available to all parts
of the module, and the signal may be traced through the various stages, using
an oscilloscope, millivoltmeter, or even high impedance headphones. Refer to
the Block Schematic which shows the signal flow through the modules. When a
point is reached where the signal is not present, or is distorted, the probable
faulty components can then be checked and if necessary replaced. Integrated
circuits, due to their internal complexity, are the most likely causes of problems
followed by mechanical components such as switches and faders, which are
susceptible to physical contamination from oxidisation, dust, and liquids.
REMOVING MODULES
Remove the two module retaining screws, which will allow the module to be
carefully withdrawn from the console. The ribbon cable will now be exposed,
and may be detached from the module. The module will still have some cables
attached, but these are sufficiently long to allow the module to be completely
withdrawn from the console. Extender cables can now be plugged into the main
ribbon cable, and the module, taking care not to twist the extender cable.
Although damage to the module will not be caused by plugging and unplugging
the module with the power still switched on, this is not recommended for the
inexperienced, as it is possible to bend the connector pins if care is not taken.
METER ALIGNMENT
Each V.U. meter has its own individual drive circuit on the circuit board of the
meters. This card also contains the detection and drive circuitry for the peak
LED which is pre-set to indicate a peak level of 8dB above OVU,
OVU is normally adjusted to indicate a line level of +4dBv, i.e., a level of 1.228
volts. However, it can be re-adjusted to indicate a different line level if required
by the pre-set potentimeter on the drive card.
Connect a millivoltmeter to the group output. Route the oscillator set to 1kHz
to the group output level to read the required level on the millivoltmeter.
(Normally this would be +4dBv). Adjust the VU drive pre-set to indicate OVU
on the VU meter and repeat for all other groups and the stereo Mix meters.
Note that the peak LED will always indicate a level of 8dB above whatever the
OVU level has been set at.
6.04
6.05
Page 33
LAMP REPLACEMENT
Illumination of the VU meters is provided by 2 lamps in each meter, these are
6 volt lamps wired in series. The lamps in each pair of meters are wired In
series and powered by the + 17 volt audio supply. A series resistor in each
meter pair provides turn on current limiting to prolong the lamp life.
To replace the lamp remove the VU meter from the panel. This is done by the
following method:-
|. Remove the two plastic clamps
2 Unscrew the two screws through the P.C.B.
3. Desolder the illumination wires from the tags on the meter.
The meter can now be slipped free and the front removed to change the bulbs.
POWER SUPPLY SERVICING
The series 400B power supply provides the following regulated supply rails;
i)
ii)
+ 17 volts Audio
+ 48 volts Phantom Power
If a power supply fault is suspected, first ensure that it really is the P.S.U. which
is at fault, and not a short circuit in the console. This can be checked by
disconnecting the P.S.U. from the console, and measuring the voltage at the
connector. A load across the supply should be provided, to simulate the normal
load conditions imposed by the console,
A 10ohm, 20 watt resistor should be connected across each of the audio rails.
The Phantom power supply can be loaded with a 2.2kohm, | watt resistor.
The ripple and noise value of the various supply rails can now be measured, using
a millivoltmeter or an oscilloscope.
If a fault is found to exist in the P.S.U. disconnect the mains supply and remove
the cover. Check visually for any obvious problems, such as blown fuse, burnt
components etc. If nothing obvious is observed, reconnect the mains, and measure
the voltages across the various electrolytic smoothing capacitors, which should
be as follows: |
Audio Supply “CI = +26 volts
C2 = -26 volts
Phantom Supply C12 = +59 volts
Difference of +10% are acceptable, due to variations in the incoming mains
voltage. If satisfactory, the problem lies in the regulator section. If not however,
check the bridge rectifier, smoothing capacitor and transformer for failure.
Page 34
7.00 RECOMMENDED SPARES KIT
SEMICONDUCTORS
Transistor 842GR Soundcraft Part No. BDO0301 (2)
Transistor 1681BL Soundcraft Part No. 6$8D0302 (2)
Transistor PN4355 Soundcraft Part No. BD0312 (2)
Single Op Amp IC TL071 Soundcraft Part No. $8BE0404 (2)
Dual Op Amp IC TL072 Soundcraft Part No. 8E0413 (2)
Single Op Amp IC 5534 Soundcraft Part No. $8E0407 (1)
Dual Op Amp IC 5532 Soundcraft Part No. $8BE0428 (1)
Quad Analogue Gate DG308 Soundcraft Part No. BFO0517 (1)
POTENTIOMETERS
Input Gain and TB vol
(10KRD) Soundcraft Part No. DM1104 (1)
Eq. Lift and Cut (10KB) Soundcraft Part No. DM1102 (1)
Eq. Frequency (100KRDx2) Soundcraft Part No. DMI1106 (1)
Aux sends/masters, monitor
sends and monitor vol
(10KA) Soundcraft Part No. DMI1103 (2)
Phones volume (10KAx2) Soundcraft Part No. DMI1105 (1)
Pan (10KBx2) Soundcraft Part No. DMI1101 (1)
All faders Soundcraft Part No. DD0316 (1)
MISCELLANEOUS
Green Led. Soundcraft Part No. JA0001 (1)
Red Led. Soundcraft Part No. JA0002 (1)
V.U. meter Soundcraft Part No. 2300315 (1)
V.U. meter bulb Soundcraft Part No. JB0122 (5)
Fader knob - white Soundcraft Part No. KA0027 (2)
red Soundcraft Part No. KA0028 (1)
yellow Soundcraft Part No. KA0029 (1)
Brown control knob Soundcraft Part No. KA0030 (5)
Cap for above red Soundcraft Part No. KC0235 (1)
black Soundcraft Part No. KC0230 (1)
orange Soundcraft Part No. | KC0234 (1)
blue Soundcraft Part No. KC0231 (1)
green Soundcraft Part No. | KC0232 (1) ”
yellow Soundcraft Part No. >KC0236 (1)
All switches Soundcraft Part No. DF0516 (1)
Module retaining screws Soundcraft Part No. NA0084 (15)
N.B. The above spares are available as a kit in the quantities noted in brackets.
This kit is suitable for End Users not wanting to keep large stock levels.
To order please quote the Soundcraft Part No. RZ2240.
Page 35
The benefit of this Warranty may not be assigned by the End User.
End Users who are consumers should note their rights under this Warranty
are In addition to and do not affect any other rights to which they may
be entitled against the seller of the Equipment.