Allen&Heath WZ 20S SERVICE MANUAL

ALLEN&H

EATH

WARNING – HIGH VOLTAGES

Power Supply Unit (PSU) work should only

e carried out by qualified personnel.

b

We recommend that you use an approved Allen & Heath

service centre for all power supply work.

Please contact your local Allen & Heath distributor for more details.

http://www.allen-heath.com/

MixWizard Series

WZ20S

Stereo Audio Mixing Console

SERVICE MANUAL

Publication No: AP3638

CONTENTS

INTRODUCTION, SERVICE AND TECHNICAL SUPPORT.................3

FLIGHTCASING THE CONSOLE & DIMENSIONS .............................4

SPECIFICATIONS & CONNECTIONS.................................................5

ORDERING A MIXWIZARD WZ20S UNIT, OPTIONS & MANUALS ....6

ORDERING SPARE ASSEMBLIES......................................................6

ORDERING SPARE PARTS.................................................................7-8

MONO INPUT BOARD COMPONENT IDENT.....................................AG3379

MONO INPUT BOARD CIRCUIT DIAGRAM........................................C3379

STEREO INPUT BOARD COMPONENT IDENT .................................AG3408

STEREO INPUT BOARD CIRCUIT DIAGRAM....................................C3408

LEFT BOARD COMPONENT IDENT...................................................AG3627

LEFT BOARD CIRCUIT DIAGRAM (PAGE 1 OF 2)................................C3627

LEFT BOARD CIRCUIT DIAGRAM (PAGE 2 OF 2) ................................C3627

RIGHT BOARD COMPONENT IDENT.................................................AG3626

RIGHT BOARD CONNECTOR CIRCUIT DIAGRAM (PAGE 1 OF 2)......C3626

RIGHT BOARD CONNECTOR CIRCUIT DIAGRAM (PAGE 2 OF 2)......C3626

CONNECTOR BOARD COMPONENT IDENT.....................................AG3632

CONNECTOR BOARD CIRCUIT DIAGRAM (PAGE 1 OF 3)..................C3632

CONNECTOR BOARD CIRCUIT DIAGRAM (PAGE 2 OF 3)..................C3632

CONNECTOR BOARD CIRCUIT DIAGRAM (PAGE 3 OF 3)..................C3632

Warning to the Service Engineer

Allen & Heath warns that any unauthorised changes or modifications to the WZ20S unit may
invalidate the legal compliance of the unit and could void the user’s authority to operate the
equipment.

WZ20S Service Manual AP3638 Issue 2. Copyright © 2005 Allen & Heath. All rights reserved

MANUFACTURED IN ENGLAND BY: ALLEN & HEATH AGENT:

ALLEN&HEATH

Kernick Industrial Estate
Penryn, Cornwall, TR10 9LU. UK

http://www.allen-heath.com

2 WZ20S SERVICE MANUAL

Introduction

The information presented in this manual is intended for competent technical personnel to carry out
service and product support for the MixWizard WZ20S console. We assume that the reader is
familiar with the related electronic theory and audio terminology, and is able to carry out basic
servicing, faultfinding and repair of audio equipment of this type. Service personnel should also be
familiar with audio systems, mains earthing and power requirements, as well as handling precautions.

For information on the configuration, operation and application of the MixWizard WZ20S
please refer to the User Guide.

Whilst we believe the information in this manual to be reliable we do not assume responsibility for
inaccuracies. We also reserve the right to make changes in the interest of further product
development.

Service and Technical Support

Under normal operating conditions the MixWizard WZ20S does not require user maintenance or
internal calibration. Any service work required should be carried out by qualified technical personnel
only.

We are able to offer further product support through our worldwide distribution network. To help us
provide an efficient service please quote the console serial number, the date and place of purchase in
any communication regarding this product.

SAFETY WARNING!

Mains electricity is dangerous and can kill. Mains voltage is
present within the unit.
Do not remove the cover with mains electricity connected. To
ensure your safety, mains earth is connected to the chassis
through the power lead. Do not remove this mains earth
connection.
To avoid the risk of fire, replace the mains fuse with the correct
value and type as indicated on the rear panel.

Before switching on your console, check that the fuse is of the correct rating and
type. This is clearly marked on the rear panel. Do not replace the fuse with any
other type, as this could become a safety hazard and will void the warranty.

General Precautions

Your WZ20S is ruggedly constructed to give many years of reliable operation. However, you will
extend the life of the console and preserve its cosmetics by applying these simple common sense
precautions.

• Avoid storing or using the mixing console in conditions of excessive head or cold, or in positions

where it is likely to be subject to vibration, dust dirt or moisture.

• Do not use any liquids to clean the control surface of the console, a soft dry brush or dry lint-free

cloth is ideal.

• Use only water or ethyl alcohol to clean the trim and scribble strips. Other solvents may cause

damage to paint or plastic parts.

• The faders, switches and potentiometers are lubricated for life. The use of electrical lubricants on

these parts is not recommended.

• Avoid using the console close to strong sources of electromagnetism radiation (e.g. video

monitors, high power electric cabling): this may cause degradation of the audio quality due to
induced voltages in connecting leads and chassis.

WZ20S SERVICE MANUAL 3

Flightcasing the Console

If the console is to be regularly moved we recommend that it is installed in a foam-lined flightcase. At
all times avoid applying excessive force to any knobs, switches or connectors.

Dimensions for flightcasing the console are shown below:

Dimensions

Width Height Depth

Desktop ........................ 483mm (19”)................. 192mm (7.6”).................530mm (20.9”)

Rack mounted .............. 483mm (19”) ................. 444mm (17.5”) 10U .......135mm (5.3”)

Packed.......................... 590mm (23.2”).............. 260mm (10.2”)...............610mm (24”)

Unpacked Packed

Weight........................... 10kg (22lbs).................. 13kg (29lbs)

4 WZ20S SERVICE MANUAL

Specifications

0dBu = 0.775 Volts rms +4dBu = 1.23V rms

0dBV = 1 Volt rms -10dBV = 316mV rms

INTERNAL HEADROOM:

....................................... Channels ........................+21dB

....................................... Mix to output................... +23dB

MAXIMUM OUTPUT LEVEL:

XLR ..........................................+26dBu into >2k ohm load

TRS jack ...................................+21dBu into >2k ohm load

PEAK INDICATORS:..............Turn on 5dB before clipping

METERS:

........... MIX 1,2 / MONITOR Peak reading 12 led 3 colour

FREQUENCY RESPONSE:

......................................................20Hz to 50kHz +0/-1dB

DISTORTION: THD+noise @ +14dBu 1kHz

............................................................................ < 0.006%

CROSSTALK: Channel shutoff measured at 1kHz

................................................................................ < 90dB

NOISE: Measured rms 22Hz to 22kHz

MIC EIN: referred to 150 ohm source

................................................................................-128dB

RESIDUAL OUTPUT NOISE:

........................................... XLR -90dBu (-94dB S/N)

........................................... TRS jack -94dBu (-94dB S/N)

MIX NOISE, CH ROUTED:

........................................... XLR -86dBu (-90dB S/N)

........................................... TRS jack -90dBu (-90dB S/N)

POWER SUPPLY: 100 to 240V AC @ 50/60Hz

Internal switch mode power unit with auto sensing mains
input.

Power Consumption............................................35W max

Mains fuse rating 100-240VAC .................T500mA 20mm

Connections

INPUTS:

Mic in...................... XLR.....................pin 2 hot, 3 cold, balanced ..............................2k Ohm......... variable –60 to -20dBu

Line in..................... TRS jack.............tip hot, ring cold, balanced ..............................>10k Ohm..... variable –30 to +10dBu

Stereo Ch in A........ RCA PHONO ......unbalanced......................................................>10k Ohm..... variable –20 to +10dBu

Stereo Ch in B........ TRS jack ............. tip hot, ring cold balanced ...............................>10k Ohm..... variable –20 to +10dBu

EXT in 1-2 .............. TRS jack.............tip hot, ring cold balanced ...............................>10k Ohm..... variable –10dBV (+4dBu option)

OUTPUTS:

Direct out 1-4.......... TRS jack.............tip hot, ring cold, impedance balanced..........<75 Ohm ........ 0dBu

Mix out 1-2 ............. XLR.....................pin 2 hot, 3 cold, balanced ............................<75 Ohm ........+4dBu

Mix out 2................. TRS jack.............tip hot, ring cold, impedance balanced..........<75 Ohm ........ -2dBu

Mono out ................ XLR.....................pin 2 hot, 3 cold, balanced ............................<75 Ohm ........ +4dBu

Aux out 1-6............. TRS jack .............tip hot, ring cold, impedance balanced..........<75 Ohm ........ -2dBu

Phones out 1, 2...... TRS jack .............tip left, ring right.............................................for stereo headphones 75 to 600 Ohms

INSERTS:

Mono Channel:

Send....................... TRS jack ............. tip send, ring return, unbalanced................... <75 Ohm ........ 0dBu

Return .................... TRS jack ............. tip send, ring return, unbalanced...................>3k Ohm

Mix out 1-2:

Send....................... TRS jack ............. tip send, ring return, unbalanced...................<75 Ohm ........ -2dBu

Return .................... TRS jack ............. tip send, ring return, unbalanced...................>7k Ohm

WZ20S SERVICE MANUAL 5

ORDERING A CONSOLE

To order a new MixWizard console please specify the model number and AC mains voltage.

MODEL DESCRIPTION ORDER CODE

MIXWIZARD WZ20S 4 Mono + 8 Stereo Input Channels WZ20S/volts

ORDERING AN OPTION

To order an option please specify the model number required.

RIAA OPTION WZ20S RIAA DUAL INPUT OPTION W21442/20S-RIAA

FADER START WZ20S MONO FADER START OPTION 002-496

FADER START WZ20S 4M8S FADER START OPTION 002-501

MANUALS AND SUPPORT DOCUMENTATION

DESCRIPTION ORDER CODE

MIXWIZARD WZ20S User Guide AP3634

MIXWIZARD WZ20S Service Manual AP3638
MIXWIZARD WZ20S Flyer AP3637

SERVICE TOOLS

The tools required to service the MixWizard WZ20S are standard to an electronics service workshop
and are easily obtainable. The following items are necessary for disassembly and service access:

1-point Crosshead screwdriver (M3, M4, 4AB) AT0004

11mm AF Nutdriver (potentiometer, headphone socket and jack nuts)

ORDERING AN ASSEMBLY

The following assemblies for the MixWizard WZ20S are supplied fully tested. Please quote the
description and order code for the part required.

Printed circuit board (PCB) assemblies:

Mono Input PCB assembly 002-483
Left PCB assembly 002-484
Right PCB assembly 002-485
Stereo PCB assembly 002-487
Connector PCB assembly including Power Supply 002-486

IDC connector harnesses:

WZ20S 16 way Main harness AL3669
WZ12/16/20S/464 34 way Master harness AL3518

6 WZ20S SERVICE MANUAL