Yamaha SPX990 Service Manual

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SPX990

Yamaha SPX990 Specifications

General

Sampling Frequency	44.1 kHz
Dynamic Range	90dB
Type	Digital Multi-Effect Processor
Total Harmonic Distortion	0.03%
Input Connectors	XLR, 1/4" TRS
Output Connectors	XLR, 1/4" TRS
MIDI	In, Out, Thru
Power Supply	AC 120V, 60Hz
Effects	Reverb, Delay, Modulation, Pitch Change
Dimensions	480 x 44 x 280 mm
Weight	3.5 kg
Frequency Response	20Hz - 20kHz (+1dB, -3dB)

Summary

Important Notices and Safety Warnings

General Safety Warnings

Provides critical safety instructions and warnings for servicing the product to prevent injury or damage.

Chemical Content Notice

Alerts users about potential chemical hazards in components and safe handling procedures.

Specifications Overview

Electrical & Audio Characteristics

Details on frequency response, dynamic range, distortion, input/output levels, and impedance.

Input, Output & Conversion Specifications

Panel Layout and Identification

Front Panel Controls and Indicators

Identifies and describes the functions of front panel buttons, knobs, and displays.

Rear Panel Connectors and Switches

Details the rear panel's input/output jacks, MIDI terminals, and switches.

System Block Diagram

Overall System Block Diagram

Shows the functional blocks and signal flow of the SPX990 processor.

Disassembly Procedures

Top Cover and Front Panel Removal

Step-by-step instructions for removing the top cover and front panel assembly.

Rear Panel and AD Circuit Board Removal

LSI Pin Descriptions

CPU and ACIA LSI Pinouts

Digital EQ and DSP LSI Pinouts

Filter, Driver, and Other LSI Pinouts

Gate Array LSI Pinout

Integrated Circuit Block Diagrams

Logic IC Diagrams

Analog IC Diagrams

Test Program Procedures

Test Program Overview and Preparation

Covers test setup, initiation, navigation, and overall program flow.

Basic Operation and Interface Tests

MIDI, RAM, and System Reset Tests

DSP and DEQ Performance Tests

Memory and Circuit Board Tests

Checks and Adjustments

Preparation and Basic Performance Checks

Covers unit preparation and checks for gain, frequency response, distortion, output, and noise.

Circuit, Voltage, and Level Meter Checks

Adjustment Procedures

Detailed steps for adjusting clipping levels and audio gain settings.

Error Messages Guide

Interpreting Error Codes

Lists error codes (E1-E4) and their corresponding meanings for troubleshooting.

MIDI Data Format Specifications

1. Transmission Conditions

2. Transmission Data: System Information

4-1 Channel Information

MIDI Implementation Chart

MIDI Protocol Compatibility

Details transmitted and recognized MIDI messages and system modes.