Korg A4 User Manual

SERVICE
MANUAL
CONTENTS
1.
SPECIFICATIONS
1
2.
STRUCTURAL
DIAGRAM
3
3.
BLOCK
DIAGRAM
5
4.
CIRCUIT
DIAGRAM
6
5.
P.C. BOARDS
7
6.
HOWTO
DISASSEMBLY
9
7.
DIAGNOSTIC
TEST
11
8.
REFERENCE
DATA
18
9.
PARTS
LIST
26

Korg A4 Specifications

General

Power	9V DC
MIDI	No
Inputs	1/4" instrument input
Outputs	1/4" output
Type	Guitar multi-effects processor

Summary

Specifications

Structural Diagram

Block Diagram

Circuit Diagram

P.C. Boards

How to Disassemble

Diagnostic Test

System Checks (Battery, MIDI, CPU)

Verifies internal battery voltage, MIDI circuitry, and CPU type.

User Interface Checks

Tests front panel switches, LEDs, parameter knobs, and volume pedal.

External Control Jacks Check

Confirms the ON/OFF status of EXT.CTRL OUT 1 and 2 jacks.

Signal Processing and Output Tests

Checks DSP, Tuner, and Peak LED functionality.

Test Mode Completion

Details procedures for ending test mode and loading preload data.

Reference Data

CPU Pin Assignments and Functions

Details pin assignments and functions for the MB89710A CPU.

ADC and DAC Block Diagrams and Pinouts

Provides block diagrams and pin functions for AK5349 ADC and AD1868 DAC.

DSP Pin Assignments and Functions

Details pin assignments and functions for the TMS57002 DSP.

Parts List

Parts List for A4GTR

Lists all part codes, names, and specifications for the A4GTR model.

Parts List for A4BASS

Lists all part codes, names, and specifications for the A4BASS model.