KORG A4 SERVICE MANUAL

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GUITAR/BASS

SERVICE MANUAL

CONTENTS

BLOCK DIAGRAM
CIRCUIT DIAGRAM

P.C. BOARDS

HOW TO DISASSEMBLY
DIAGNOSTIC TEST
REFERENCE DATA
PARTS LIST

I.
2.
3.
4.
5.
6.
7.
8.
9.

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1. SPECIFICATIONS

FOR A4GTR

Internal Effects

- Programs

Front panel

Rear panel

Sampling Frequency:
Dynamic Range

TUNER

Power Supply
Power Consumption

Maximum Input
Level/Impedance

Maximum Output
Level/Impedance

Dimensions

Weight

: COMPRESSOR, OISTORTION/OVERDRIVE, 3 BAND EO, PITCH/DELAY.

CHORUS/FLANGER, REVERE. AMP SIMULATION, NOISE REDUCTION

: Preset; 30 programs

User programable; 80 programs

1 Volume; INPUT VOLUME. PARAMETER EDITORS. OUTPUT VOLUME

Keys/Switches; BANK UP SWITCH, WRITE REY. USER/PRESET KEY,
BYPASS/TUNE SWITCH. EFCT/PROG SWITCHES, PROS/EDIT SWITCH,
MODE(Effect)SELECT REYS(UP. DOWN)

Display; BANK/VALUE Display (8 segment LED x 2)

Dot type LEDs; EFCT/PROG LEDs, MODE LEDs, Peak indicator

2 Power Switch, DCSV Jack, INPUT Terminal. OUTPUT Terminals

(L/MONO, R). PHONE Jack. VOLUME PEDAL Jack, EXTERNAL CONTROL
OUTPUT Terminals (l, 2). MIDI Terminals (MIDI IN, MIDI OUT)

48 RN:

2 90dB or more(IHF-A. when bypassing)

2 Measurement Range; A0-C7

Measurement Accuracy; $0.5 cent.

: DCSV

Z 350mA

2 +7dBu/1Mfl

: +7.5dBu/1kfl
: 498(M) x 227.5(0) x 48.7(H)mm

: 2.2ke

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(5.

LED MATRIX FOR A4 GTR

LINEI LINEZ LINE3 LINE4 LINES
(P70) (P71) (P72) (P73) (P50)

LEDl(P40) EFFECT dp DP ' BYP/TUN 3BAND E0
EDIT PEDAL MODE

LEDZ(P41) TUNE e E COMP UTILITY
+1 PEDAL MODE
LEDS(P42) TUNE d D DIST/OD REVERB
O PEDAL MODE
LE04(P43) TUNE s G SBAND E0 CH/FL
-l PEDAL MODE

LED5(P44) TUNE a A PIT/DLYZ
2 MODE
LED8(P45) USER f F PIT/DLY COMP
PEDAL MODE

LED7(P46) PROG c C REVERE DIST/OD
PEDAL MODE

LEDS(P47) TUNE b B CH/FL PIT/DLYI
+2 PEDAL MODE

X LINEZ and LINE3 are the ports for the 7-seslent LEDs.

(4) When this check ends, press [WRITE] to proceed to the next check.

PARAMETER KNOB CHECK )

(I) Here. the pare-eter knobs (A-F) on the panel and the volume pedal functions are
checked.

(2) First. when the knob is turned fully to the right (for the volume pedal.
when the pedal is pressed back as far as possible), this check confirms whether
the corresponding LED changes tron a blinking state to a steady-lit state.

(3) Next. when the knob is turned fully to the left (for the volume pedal,
when the pedal is pressed forward as for as possible). this check confirms
whether the corresponding LED goes out.

(4) The check proceeds one by one, in sequence fro- knob A.

(5) The table below shows the knobs and their corresponding LEDs.

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