ALLEN & HEATH ZED 420 User manual

ALLEN&HEATH ZED 4 bus service manual AP7224 Issue 4 Page - 1 - of 11
ZED 420 ZED 428 ZED 436
ALLEN&HEATH
SERVICE MANUAL
Copyright © 2007 Allen & Heath Limited. All rights reserved
Allen & Heath Limited
Kernick Industrial Estate, Penryn, Cornwall, TR10 9LU, UK
http://www.allen-heath.com
ZED
4 bus

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Release notes for this issue
First issue – no release notes.
Limited One Year Warranty
This product is warranted to be free from defects in materials or workmanship for period of
one year from the date of purchase by the original owner. To ensure a high level of
performance and reliability for which this equipment has been designed and manufactured,
read this User Guide before operating. In the event of a failure, notify and return the
defective unit to ALLEN & HEATH Limited or its authorised agent as soon as possible for
repair under warranty subject to the following conditions
Conditions of Warranty
The equipment has been installed and operated in accordance with the instructions in this
User Guide. The equipment has not been subject to misuse either intended or accidental,
neglect, or alteration other than as described in the User Guide or Service Manual, or
approved by ALLEN & HEATH. Any necessary adjustment, alteration or repair has been
carried out by ALLEN & HEATH or its authorised agent. This warranty does not cover fader
wear and tear. The defective unit is to be returned carriage prepaid to ALLEN & HEATH or its
authorised agent with proof of purchase. Units returned should be packed to avoid transit
damage. In certain territories the terms may vary. Check with your ALLEN & HEATH agent
for any additional warranty which may apply.
For further assistance please contact our distributor or your territory.
http://www.allen-heath.com/UK/distributors.asp

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CONTENTS
DEVELOPMENT CHANGES
SERVICING PRECAUTIONS AND GENERAL NOTES
PARTS IDENTIFICATION
•How to order parts
•Exterior parts
•Interior parts
SOFTWARE & FIRMWARE
SPECIFICATION

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DEVELOPMENT CHANGES
NOTE: These changes have been implemented at the factory as part of our ongoing
development policy.
They are not critical to the basic function of the unit.
It is for the owner / service engineer to decide to update a unit with development changes.

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Servicing Precautions – General Notes
Service personnel:
Service work should be carried out by technically qualified service personnel only.
Mains power is dangerous and can kill. Do not attempt to work on a linear or switched
mode power supply if you are not suitably qualified to do so. Do not attempt to repair
surface mount circuit assemblies unless you are suitably qualified and have the
necessary facilities to do so. Replacement circuit assemblies can be ordered.
Service facilities:
Ensure a suitably sized work surface is available. Ensure this is clear of dirt, debris and
obstructions which may damage the equipment surfaces. Ensure adequate lighting.
Use the correct tools for the job and ensure they are in good working order. Ensure all
workshop safety requirements are adhered to.
Service information:
Check that you have all the information you need before starting the service job. Refer
to the Allen & Heath web site or contact Allen & Heath technical support for details on
the latest information. Full technical information can be downloaded from the web site
Distributor Zone (password required).
Mains power:
Connect the equipment to mains power only of the type described in the user guide and
marked on the rear panel. The power source must provide a good ground connection.
Ensure you always use an isolation transformer when working on any mains power
supply unit.
Mains cord and fuse:
Use the correct power cord as supplied with the equipment. Do not remove or tamper
with the ground connection in the power cord. Heed the Important Mains Plug Wiring
Instructions printed in the user guide if it is necessary to rewire the mains cord. Always
replace the equipment mains fuse with the correct type and rating as described in the
user guide and marked on the equipment panel.
Opening the unit:
Switch off and remove the mains power cord before opening the equipment. Ensure all
power supply covers and safety shields are in place before applying power with the unit
open for diagnostic fault finding.
Closing the unit:
Before finishing, check the quality and accuracy of the service work carried out.
Remove any dirt or debris as this may cause equipment failure in the future. Ensure all
assemblies, harnesses and connectors are correctly aligned and plugged in. Ensure
that jumper settings and control configurations are correctly set according to the
requirements of the customer.
Continued -

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Testing the unit:
Before operating the equipment, read and adhere to the Important Safety Instructions
printed in the user guide. Test that the service work has been successfully carried out.
Shipping the unit:
Use adequate packing such as the original packaging or purpose designed flight case if
you need to ship the unit. To avoid injury to yourself or damage to the equipment take
care when lifting, moving or carrying the equipment.
Operation:
To test the console make sure it is connected as described in the user guide. Check
that the voltage setting marked on the rear panel is correct for the local mains supply.
Fault finding:
For effective fault diagnosis trace the signal flow through the circuit path. Refer to the
system block diagram. Replacement circuit assemblies are available from Allen &
Heath.

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Switch cap
Round Grey
AJ3955
Switch cap
Rectangle White
AJ7180
Switch cap
Rectangle Grey
AJ7179
Switch cap
Squre Grey
AJ7210
How to order parts
Parts must be ordered from our distributor in your territory. A list of international distributors can be viewed at http://www.allen-
heath.com/UK/distributors.asp
UK parts must be ordered through an appointed A&H dealer or service centre. A list of UK service centres can be viewed at
http://www.allen-heath.com/UK/service_centres.asp
PARTS IDENTIFICATION
EXTERIOR PARTS:
Knob Grey
AJ2078A
Knob Blue
AJ2075A
Knob Red
AJ6949
Knob Black
AJ6106A
Switch cap
Rectangle Black
AJ7812
Fader knob
Grey
AJ6278
Fader knob
Blue
AJ6237
Fader knob
Black
AJ6278
Plastic side
moulding left
AA6983-LJIT
Plastic side
moulding right
AA6983-RJIT
Feet
AK0102
Nut pot
AB8050
Nut & socket
(supplied with complete
socket)
AL6893
Fader knob
Red
AJ6950
Small
headphone
socket
A
L5323

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Fader mono group/master
003-662JIT
Fader mono
003-780JIT
Fader stereo
003-663JIT
Mono
Gain
AI8174
Frequency
AI8004
Boost/cut
AI8005
Pan
AI8008
Aux
AI8008
Headphone
AI8007
Mono Stereo
Boost/cut
AI8006
Aux
AI8003
Pan
AI8008
Aux master
AI8003
Pan
AI8008
Matrix
AI8003
Level
AI8003
Talkback
AI8111
Stereo Gain
AI8007

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INTERIOR PARTS:
003-732JIT
Mono i/p
003-733JIT
Stereoo i/p
003-734JIT
Group 1
003-735JIT
Group 3
003-734JIT
Group 2
003-736JIT
Group 4
USB
003-738JIT
Master Right
003-737JIT
Master Left
003-739JIT
Distribution
003-740JIT
Master out
003-746JIT
Mono-R meter
003-741JIT
PSU
Fan AM6601

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Screws:
Screw front
panel
AB4661
Screw fader
AB4661
Screw XLR
AB2810
Screw base
AB4661
Screw side
moulding
AB6889

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SPECIFICATIONS:
Operating Levels
Inputs
Mono channel (XLR) Input +6 to –63dBu for nominal (+17dBu in max)
Mono channel Line Input (Jack socket) +10 to –26dBu (+30dBu maximum)
Insert point (TRS Jack socket) 0dBu nominal +21dBu maximum
Stereo Input (Jack sockets) 0dBu nominal (control = Off to +10dB)
Stereo input (phono sockets) 0dBu nominal (control = Off to +10dB)
2 Track Input (phono sockets) 0dBu nominal +21dBu maximum
Outputs
L, R & Mono Outputs (XLR) +4dBu nominal. +27dBu maximum.
L, R & M Insert (TRS Jack socket) -2dBu nominal +21dBu maximum
Group Outputs (Jack sockets) +4dBu nominal. +27dBu maximum.
Group Insert (TRS Jack socket) -2dBu nominal +21dBu maximum
Aux Outputs (Jack sockets) -2dBu nominal +21dBu maximum (Bal Option +4)
Matrix Outputs (TRS Jack socket) -2dBu nominal. +21dBu maximum. (Bal Option +4)
2 Track Output (phono sockets) 0dBu nominal. +21dBu maximum.
Direct Out (TRS Jack socket) 0dBu nominal. +21dBu maximum.
Frequency Response
Mic in to Mix L/R Out, 30dB gain +0.5/-1dB 20Hz to 20kHz.
Line in to Mix L/R out 0dB gain +0.5/-1dB 10Hz to 30kHz
Stereo in to Mix L/R out +0.5/-1dB 10Hz to 30kHz
THD+n
Mic in to Mix L/R Out, 0dB gain 1kHz +10dBu out 0.004%
Mic in to Mix L/R Out, 30dB gain 1kHz 0.014%
Line in to Mix L/R out 0dB gain 0dBu 1kHz 0.005%
Stereo in to Mix L/R out 0dB gain +10dBu 1kHz 0.003%
Headroom
Analogue Headroom from nominal (0Vu) 21dB
USB in & out headroom from nominal (0Vu) 14dB
USB Audio CODEC (Coder/Decoder)
USB Audio In/Out USB 1.1 compliant 16bit.
Sample Rate 32, 44.1, or 48kHz
Noise
Mix Noise, LR out, 16 channels routed, Ref +4dBu, 22-22kHz -90dB (-86dBu)
Mix Noise, LR out, 24 channels routed, Ref +4dBu, 22-22kHz -89dB (-85dBu)
Mix Noise, LR out, 32 channels routed, Ref +4dBu, 22-22kHz -88dB (-84dBu)
Mic Pre EIN @ max gain 150R input Z 22-22kHz -127dBu