RODE Microphones AI-1 User manual

AI-1 SERVICE MANUAL
Spetember 9, 1994
Revision 2.02

PREFACE
This document is intended to assist the service technician in the operation, maintenance and repair of
the AI-1 Digital Interface. This unit represents one of the building blocks of the complete ADAT
system. Together with the AI-1 Reference Manual, this document provides a complete description of the
functionality and serviceability of the AI-1. Any comments or suggestions you may have pertaining to
the document are welcome and encouraged.
WARNINGS
TO REDUCE THE RISK OF ELECTRIC SHOCK OR FIRE, DO NOT EXPOSE THIS
PRODUCT TO WATER OR MOISTURE.
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
The arrowhead symbol on a lightning flash inside a triangle is intended to alert the user to
the presence of un-insulated "dangerous voltage" within the enclosed product which may
be of sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point inside a triangle is intended to alert the user to the presence of
important operating, maintenance and servicing instructions in the literature which
accompanies the product.
REPAIR BY ANY PERSON OR ENTITY OTHER THAN AN AUTHORIZED ALESIS
SERVICE CENTER WILL VOID THE ALESIS WARRANTY.
PROVISION OF THIS MANUAL DOES NOT AUTHORIZE THE RECIPIENT TO COMPETE
WITH ANY ALESIS DISTRIBUTOR OR AUTHORIZED REPAIR SERVICE CENTER IN THE
PROVISION OF REPAIR SERVICES OR TO BE OR MAKE REPAIRS AS AN AUTHORIZED
SERVICE CENTER.
ALL REPAIRS DONE BY ANY ENTITY OTHER THAN AN AUTHORIZED ALESIS
SERVICE CENTER SHALL BE SOLELY THE RESPONSIBILITY OF THAT ENTITY, AND
ALESIS SHALL HAVE NO LIABILITY TO THAT ENTITY OR TO ANY OTHER PARTY
FOR ANY REPAIRS BY THAT ENTITY.
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SAFETY SUGGESTIONS
Carefully read the applicable items of the operating instructions and these safety suggestions before
using this product. Use extra care to follow the warnings written on the product itself and in the
operating instructions. Keep the operating instructions and safety suggestions for reference in the future.
1. Power Source. The product should only be connected to a power supply which is described either in the operating
instructions or in markings on the product.
2. Power Cord Protection. AC power supply cords should be placed such that no one is likely to step on the cords and such
that nothing will be placed on or against them.
3. Grounding the Plug. This product has a 3-wire grounding type of plug (a plug with a grounding pin) for safety purposes.
This plug can only be used in a grounding power outlet. If the plug does not insert into the outlet you are using, the outlet
probably is not a grounding type of power outlet. Contact your electrician to replace the obsolete outlet with a grounding
type of outlet instead of defeating the safety feature of the grounding type of plug.
4. Periods of Non-use. If the product is not used for any significant period of time, the product's AC power supply cord
should be unplugged from the AC outlet.
5. Foreign Objects and Liquids. Take care not to allow liquids to spill or objects to fall into any openings of the product.
6. Water or Moisture. The product should not be used near any water or in moisture.
7. Heat. Do not place the product near heat sources such as stoves, heat registers, radiators or other heat producing
equipment.
8. Ventilation. When installing the product, make sure that the product has adequate ventilation. Improperly ventilating the
product may cause overheating, which may damage the product.
9. Mounting. The product should only be used with a rack which the manufacturer recommends. The combination of the
product and rack should be moved carefully. Quick movements, excessive force or uneven surfaces may overturn the
combination which may damage the product and rack combination.
10. Cleaning. The product should only be cleaned as the manufacturer recommends.
11. Service. The user should only attempt the limited service or upkeep specifically described in the operating instructions
for the user. For any other service required, the product should be taken to an authorized service center as described in the
operating instructions.
12. Damage to the Product. Qualified service personnel should service the unit in certain situations including without
limitation when:
a. Liquid has spilled or objects have fallen into the product,
b. The product is exposed to water or excessive moisture,
c. The AC power supply plug or cord is damaged,
d. The product shows an inappropriate change in performance or does not operate normally, or
e. The enclosure of the product has been damaged.
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DOCUMENT REVISIONS
Revision 1.2 6/23/93 Original Issue
Revision 2.0 2/20/94 Revised entire manual. Added AI-1 QC Test Procedure.
Revision 2.01 4/1/94 Added Parts Order Forms to Appendix D. Revised Table
of Contents. Issued the following change pages:
Title Page, p. iii, p. v, pp. D-4 through D-7
Revision 2.02 9/9/94 Removed Parts Order Forms from Appendix D. Revised
Appendix D (Bill Of Material). Revised Section 1.3.
Revised Section 2.3.1.1. Removed redundant section
3.2.3 and changed it to section 3.2.4. Revised Table of
Contents. Issued the following change pages: Title Page,
pp. iii-v, p. 2, p. 4, p. 8, Appendix D
Revision 2.02 iii 9/9/94

TABLE OF CONTENTS
PREFACE............................................................................................................i
WARNINGS........................................................................................................i
SAFETY SUGGESTIONS.................................................................................ii
DOCUMENT REVISIONS................................................................................iii
TABLE OF CONTENTS ...................................................................................iv
LIST OF FIGURES............................................................................................v
LIST OF TABLES..............................................................................................v
1.0 INTRODUCTION.........................................................................................1
1.1 Scope..............................................................................................................1
1.1.1 Document Conventions ..................................................................1
1.2 AI-1 Reference Manual .................................................................................1
1.3 List Of Abbreviations....................................................................................2
2.0 AI-1 BUILDING BLOCKS..........................................................................3
2.1 AI-1 Power Supply........................................................................................3
2.2 Front Panel PCB............................................................................................3
2.2.1 Front Panel Controls.......................................................................3
2.2.1.1 ADAT Channel Group.....................................................3
2.2.1.2 Destination Rate Group ...................................................3
2.2.1.3 Source and Destination Groups.......................................4
2.3 Main PCB ......................................................................................................4
2.3.1 Main PCB Input/Output..................................................................4
2.3.1.1 ADAT Interface...............................................................4
2.3.1.2 AES/EBU Interface .........................................................5
2.3.1.3 S/PDIF Interface..............................................................5
2.3.2 Main PCB Interconnectivity...........................................................5
3.0 AI-1 REPAIR ................................................................................................6
3.1 AI-1 General Troubleshooting.......................................................................6
3.2 Main PCB Troubleshooting...........................................................................6
3.2.1 AES/SPDIF to AES/SPDIF transfers .............................................6
3.2.2 AES/SPDIF to ADAT transfers......................................................7
3.2.3 ADAT to AES/SPDIF transfers......................................................7
3.2.4 ADAT to ADAT transfers..............................................................8
4.0 AI-1 TESTING..............................................................................................10
4.1 Software Version Check................................................................................10
4.2 AI-1 Self Test Routines.................................................................................10
4.2.1 AI-1 Self Test Setup .......................................................................10
4.2.2 AI-1 Self Test Description..............................................................10
Revision 2.02 iv 9/9/94

APPENDIX A
AI-1 SCHEMATICS ...........................................................................................A-1
APPENDIX B
AI-1 HARDWARE UPGRADES........................................................................B-1
APPENDIX C
AI-1 SOFTWARE HISTORY.............................................................................C-1
Version 1.3...............................................................................................C-2
Version 1.4...............................................................................................C-2
Version 1.5...............................................................................................C-2
APPENDIX D
AI-1 PARTS LIST...............................................................................................D-1
APPENDIX E
AI-1 QC TEST PROCEDURE............................................................................E-1
1.0 Equipment Requirements...................................................................E-2
2.0 AI-1 Self Test ....................................................................................E-2
3.0 AI-1 Interface Test Setup ..................................................................E-4
4.0 ADAT to S/PDIF Interface Test........................................................E-5
5.0 S/PDIF to ADAT Interface Test........................................................E-6
6.0 ADAT to AES/EBU Interface Test ...................................................E-10
7.0 AES/EBU to ADAT Interface Test ...................................................E-12
8.0 Preparation For Delivery ...................................................................E-15
LIST OF FIGURES
Figure 3-1 - AI-1 Signal Flow.............................................................................9
Figure E-1 - Self Test Configuration...................................................................E-3
Figure E-2 - Configuration for AI-1 QC Test Procedure ....................................E-4
LIST OF TABLES
TABLE 4.1 - SELF TEST FAILURES...............................................................11
Revision 2.02 v 9/9/94

1.0 INTRODUCTION
1.1 Scope
This service manual is intended to serve as a primer to assist repair technicians in isolating and
correcting problems associated with the AI-1 Digital Interface. This service manual includes PCB
schematics, PCB comp. IDs., self test routines, and a description of the hardware operation of the AI-1
from a servicing point of view.
1.1.1 Document Conventions
Throughout this service manual, certain conventions are followed in order to make this manual
more coherent. LEDs and signal mnemonics are spelled with all capital letters (such as SOURCE and
SLAVECLK) while functions to be performed by the operator are spelled in bold capital letters (such as
PLAY or REWIND).
1.2 AI-1 Reference Manual
The AI-1 Reference Manual (Alesis P/N 7-51-1071) is included with every AI-1 sold. This
manual explains the basic operation, features, and applications of the AI-1. The manual contains
diagrams of both the AI-1 front panel controls and the rear panel interface. Moreover, the manual
contains several connection diagrams for a variety of recording situations. Please refer to this manual
when information on the operation or connectivity of the AI-1 is required.
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1.3 List Of Abbreviations
The following is a list of abbreviations to terms used throughout this service manual.
Abbreviation Definition Abbreviation Definition
A Amps (unit of current) LAN Local Area Network
AC Alternating Current LED Light Emitting Diode
AES Audio Engineering Society LRC Little Remote Control
A/D Analog to Digital MHz Mega Hertz (1,000,000 Hz)
ADA Analog/Digital/Analog MIDI Musical Instrument Digital
ADAT Alesis Digital Audio Tape Interface
ADC Analog to Digital Converter MMC MIDI Machine Code
ASIC Application Specific Integrated
Circuit MTC OSC MIDI Time Code Oscillator
BRC Big Remote Control PCB Printed Circuit Board
CD Compact Disc PG Phase Generator
D/A Digital to Analog PLCC Plastic Leaded Chip Carrier
DAC Digital to Analog Converter QC Quality Control
DAT Digital Audio Tape RAM Random Access Memory
dB Decibel RMB Remote Meter Bridge
DC Direct Current ROM Read Only Memory
DRAM Dynamic Random Access
Memory S/PDIF SMPTE Sony/Phillips Digital Interface Society of Motion Picture and
EBU European Broadcasters Union Television Engineers
EMI Electromagnetic Interference SRAM Static Random Access Memory
EQ Equalization SVHS Super Home Video System
EPROM Erasable Programmable Read
Only Memory S/W TP Software Test Point
EEPROM Electrically Erasable
Programmable Read Only
Memory
µs
V
VCA
Microseconds (1/1,000,000 sec)
Volt (unit of voltage)
Voltage Controlled Amplifier
ESD Electrostatic Sensitive Device VLSI Very Large Scale Integrated
FG Frequency Generator Circuit
GND Ground VCR Video Cassette Recorder
H/W Hardware VHS Video Home System
Hz Hertz (unit of Frequency) VCO Voltage Controlled Oscillator
IC Integrated Circuit VU Volume Unit
I/O Input/Output W Watt (unit of power)
Revision 2.02 2 9/9/94

2.0 AI-1 BUILDING BLOCKS
The AI-1 provides a means of interfacing digital audio between the ADAT digital multitrack
recorder and any other digital recording system. The AI-1 converts data from the ADAT format to either
the AES/EBU or S/PDIF interface standards and vice versa. Additionally, the AI-1 is capable of
performing sample rate conversion from 48 KHz to 44.1 KHz and vice versa. With a touch of a button,
any configuration of sending and receiving digital audio is possible, without ever leaving the digital
domain.
Within the AI-1 is a power supply, the Main PCB, and a Front Panel PCB. The Main PCB
connects to the Front Panel PCB via a ribbon cable. A description of each AI-1 building block as well as
the interconnectivity between each building block is presented in the following sections
2.1 AI-1 Power Supply
The power supply is a switching power supply that outputs 5 VDC to the main PCB. A copy of
the schematic is provided in Appendix A. However, there are no serviceable parts within this supply.
Alesis purchases this supply off-the-shelf from an outside vendor. If there is a problem with the power
supply, It is usually less time consuming to replace the whole power supply.
CAUTION: HIGH VOLTAGE. AVOID TOUCHING THE POWER SUPPLY WHEN THE
UNIT IS ON.
2.2 Front Panel PCB
The front panel PCB houses the button pads which cause the LEDs to light up when depressed.
The front panel PCB interfaces to the AI-1 main PCB via a 24-pin ribbon cable. For a description of the
pinout of this cable, refer to Appendix A of this service manual.
2.2.1 Front Panel Controls
The controls on the front panel are classified in four groups: ADAT CHANNEL,
DESTINATION RATE, SOURCE, and DESTINATION. A description of each group is provided in the
following paragraphs.
2.2.1.1 ADAT Channel Group
The ADAT CHANNEL group contains four buttons which are used to select the two ADAT
tracks that will transmit or receive digital audio. Under normal operation, that is when data is being
transferred between the ADAT and an external digital source, only one of the four ADAT CHANNEL
buttons can be enabled at any one time. However, if both the SOURCE and DESTINATION groups are
set to ADAT, all four of the ADAT CHANNEL buttons will be lit, indicating that all eight channels of
the ADAT digital bus are to be transferred.
2.2.1.2 Destination Rate Group
The DESTINATION RATE group provides the operator with the option to change the sampling
rate from 48 KHz to 44.1 KHz or vice versa. However, if the destination of the digital audio signal is the
ADAT, the DESTINATION RATE will automatically default to the 48 KHz sampling rate.
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Note that the DESTINATION RATE to the ADAT can be set at 44.1 KHz. However, the ADAT
will recognize this sampling rate as a pitch down of -147 cents.
2.2.1.3 Source and Destination Groups
The SOURCE and DESTINATION groups allow the operator to select the configuration that is
being used to transfer the digital audio. Each group contains a button for either ADAT, AES/EBU or
S/PDIF interfaces. Only one of each group's buttons can be pressed at any one time. That is, only one
source and one destination can be selected at any time. If any of the LEDs in either group flash, it
signifies that no device has been selected to receive or send the digital audio.
2.3 Main PCB
The main PCB handles and controls all the various functions of the AI-1. It contains headers
which connect this PCB to the power supply and the front panel PCB as well as numerous input and
output jacks which interface the AI-1 with the outside world.
The main PCB utilizes a CS8411 receiver (U14) and a CS8401 transmitter (U13) to allow the
digital signal to be received and sent respectively. This transmitter/receiver pair also accomplishes the
AES to S/PDIF conversion process based on the operator setup of the AI-1. A DSP56001 digital signal
processor (U38) on the main board accomplishes any sample rate conversion required.
The AI-1 contains the same Audio ASIC (U1) that is used within the ADAT for digital transfer
of data via the Alesis Fiber Optic Interface. The 80C31 micro controller (U9) is used for all of the
clocking and timing within the AI-1 while the EPROM (U10) contains the system software. Finally, an
EEPROM (U41) is used to store the current mode settings of the AI-1. That is, when the AI-1 is
powered on, the unit recalls the most recent mode of operation and lights the appropriate LEDs.
Whenever a change is made to the existing mode settings, the EEPROM is updated to reflect the current
mode settings.
For more information on the Audio ASIC or the Alesis Proprietary Digital Interface, refer to the
ADAT Service Manual.
2.3.1 Main PCB Input/Output
The main PCB contains those connectors which interface the AI-1 with the ADAT, as well as
AES/EBU and S/PDIF protocol devices. The following paragraphs describe the purpose of each type of
connector which is mounted to the main PCB.
2.3.1.1 ADAT Interface
The AI-1 contains two 9 pin D Shell female sync connectors which interface to the ADAT
System. When properly connected to the ADAT or BRC, this interface provides the sample accurate
synchronization with the ADAT system. Moreover, if the BRC is being used to control the ADAT
system in addition to other external equipment, a 48 KHz BNC connector is provided. By connecting the
BRC to the AI-1 through this connector, all clocking is controlled from the BRC. In essence, the BRC
can be used as a master clock for the entire system. The use of a standard "LAN" cable is suggested
when connecting the AI-1 to a BRC
The AI-1 also contains two fiber optic connectors to interface the digital audio to and from the
ADAT. These connectors accept the ADAT fiber optic cable for the transfer of digital data between the
ADAT and the AI-1 using the Alesis Proprietary Digital Interface.
Revision 2.02 4 9/9/94