Alesis HD24 User Manual

ALESIS
HD24 (RL)
Service Manual
P/N: 8-31-0092-B
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Alesis HD24 Specifications

General

Type	Hard Disk Recorder
Number of Tracks	24
Simultaneous Recording Channels	24
Simultaneous Playback Channels	24
A/D Resolution	24-bit
Sample Rate	44.1kHz, 48kHz, 88.2kHz, 96kHz
Hard Drive Bays	2
Connectivity	Ethernet (for file transfer)
Hard Drive Type	IDE
Sync I/O	1 x BNC Word Clock In, 1 x BNC Word Clock Out
Storage	Internal Hard Drive

Summary

Preface

ADAT HD24 Hot Keys

Restore Defaults

Restores system variables to default values to fix minor software issues.

Jump to MIDI OS loader

Forces boot software to load OS code via MIDI for software updates.

Reconfigure Hardware

Reloads PLD firmware, useful after part replacement.

Production Tests

Initiates automated self-diagnostics mode for testing.

Diagnostics Tests

Initiates manual self-diagnostics mode for testing.

ADAT HD24 Gain Stage Diagram

Balanced Input Levels

Specifies balanced input signal levels and voltage ratios.

Single-Ended to Balanced Conversion

Describes the conversion from single-ended to balanced signal levels.

ADC Input Ranges

Outlines ADC input ranges and maximum signal levels.

ADAT HD24 Switch Matrix

Front Panel Button Map

Maps front panel button labels to their corresponding switch matrix assignments.

VFD and Driver Circuitry

VFD AC and High Voltage Supply

Describes the AC and high voltage power supply for the VFD.

RL HD Backplane PCB Schematic

Centronics and IDE Connectors

IDE Standard Pinout

Pin assignments for the IDE standard interface.

IDE Power Connector Definitions

Power and control pin definitions for the IDE connector.

Engineering Change Notice B27401

Change Details

Details the specific modifications implemented in the ECN.

Reason for Change

Explains the technical justification for the engineering change.

Special Instructions

Provides specific guidance for implementing the ECN.

Material Disposition

Outlines how existing materials and units are handled during the change.

Sync In Wordclock Modification (Rev. C)

Circuit Modification Diagram

Visual guide illustrating the circuit modification steps.

Step-by-Step Modification Instructions

Step-by-step instructions for performing the circuit modification.

System Wordclock Modification (Rev. C)

Circuit Modification Diagram

Visual guide illustrating the circuit modification steps.

Step-by-Step Modification Instructions

Step-by-step instructions for performing the circuit modification.

HD Backplane ECN (9-79-0238)

PCB Modification Procedure

Details the steps for modifying the HD Backplane PCB.

Assembly Diagram for Modification

Assembly diagram showing the location of modifications.

Front View of Modification Area

Front view of the PCB assembly showing modification points.

HD Backplane Modification Views

Top View of Modification

Top view illustration of the PCB modification for the HD Backplane.

Side View of Modification

Side view illustration of the PCB modification for the HD Backplane.