CASIO AP20 Service Manual

AP-20

(with price)

ELECTRONIC KEYBOARD

CONTENTS

Safety Notice...................................................................................... 2

Specifications .................................................................................... 3

Block Diagram ................................................................................... 4

PCB Layout ........................................................................................ 5

Disassembly Instructions ................................................................. 6

Circuit Description .......................................................................... 10

Major Waveforms.............................................................................12

Troubleshooting .............................................................................. 13

Wiring Diagram ................................................................................ 17

Exploded View ................................................................................. 18

Parts List .......................................................................................... 21

Schematic Diagrams ....................................................................... 23

SAFETY NOTICE

CAUTION! Danger of explosion if battery is incorrectly replaced. Replace only with the same of equivalent type recommended by the appliance manufacturer.Discard used batteries according to manufacturer's instructions.

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SPECIFICATIONS

GENERAL

Number of keys 88 Polyphonic: 32-note Preset tones: 10, PIANO 1, PIANO 2, ELEC. PIANO, HARPSICHORD, VIBRAPHONE,

PIPE ORGAN, STRINGS, CHOIR, W.BASS (Lower tone only), E.BASS (Lower tone only)

Layer/Split function Key transpose: F#-C-F Keyboard controls: Tuning curve, Baroque pitch Temperaments: Equal Temperament, Kirnberger III, Werckmeister, Mean-Tone,

Just Intonation (Minor/Major), Pythagorean System Effects: Reverb (Room, Stage, Hall 1, Hall 2)/Chorus/Tremolo/Brilliance Demo tunes: 8, 1. Polonaise "Héroïque" (F.F. Chopin)

2. Frühlingslied Op. 62-6 (F. Mendelssohn)

3. CASIO original

4. Harmonious blacksmith (G.F. Händel)

5. CASIO original

6. Jesus, Bleibet Meine Freude (J.S. Bach)

7. CASIO original

8. CASIO original

Memory: Number of Songs: 2 (A and B)

System: Real-time recording

Memory Capacity: Approximately 3,000 notes total

Memory Backup Battery: Built-in lithium battery

Battery Life: Approximately 5 years Pedals: Soft, Sostenuto, Damper Tuning control: 440Hz ±50 cents Built-In Speakers: 16 cm dia. x 2 (Output: approx. 20 W + 20 W) MIDI: 16-channel, multi-timbral reception Terminals: PHONES 1 and 2, MIDI (IN/OUT/THRU), LINE OUT L and R (Output Imped-

ance: 10 KΩ; Output Voltage: 2 V, RMS, max.), LINE IN R and L (Input Impedance: 20 KΩ, Input sensitivity: 200 mV)

Power source: 120V (for U.S.A.),

120V, 220V, 230V and 240V (for other countries) Power consumption: 65W (with 120V AC), 55W (with 220V, 230V and 240V AC) Dimensions (HWD): Without stand: 185 × 1340 × 520 mm (7-5/16 × 52-13/16 × 20-1/2 inches)

With stand: 820 × 1360 × 550 mm (32-5/16 × 53-9/16 × 21-11/16 inches) Weight: Without stand: 35.5 kg (78.3 lbs)/38.5 kg (84.0 lbs)

With stand: 45.5 kg (100.4 lbs)/48.5 kg (106.1 lbs)

Note: There are two models of AP-20, one has a keyboard cover, the other has no keyboard cover.

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BLOCK DIAGRAM

RAM 256K

HM62256BLP-10

ROM

MX23C1010PC-

12CA25

BRILLIANCE

D0 ~ 7

A0 ~ 14

PEDAL

SF SS DP

CPU

HD6435328RC13F

HG51B155FD

MIDI

IN OUT

MIDI MIDO

A0 ~ 3

DSP

P70 ~

P77

MUTE

Keyboard Controller

HG52E35P

P12 ~

P14

Switch & LED

Controller

µPD65005GF-419

RST

Reset IC

MB3771P

RA0 ~ 19

RD0 ~ 15

EA0 ~ 14

ED0 ~ 15

KC0 ~ 7

FI0 ~ 10 SI0 ~ 10

KC0 ~ 4

KI0 ~ 3

L1 ~ 9 LA ~ J

HN62418PD25 HN624116D44

HM65256BLSP 10 × 2

Keyboard

Switches

LEDs

ROM

8M + 16M

RAM

256K × 2

AVCC

AVDD

AVFF

+12V

+5V

–12V

M527BL05

M5F78M12L × 2

Voltage Regulator

T101

Power Switch

VDD

+5V

T8, T9

LINE IN

Power Transformer

SOLM, SOLP

D/A Converter

µPD6376CX

Filter

Main

Volume

BDK, WOK1, SORM, SORP

D/A Converter

µPD6376CX

Filter

Mixer, Mute Circuit

T6, T7, T10, T11

Power Amp.

STK4132MK

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PCB LAYOUT

MA2M

PS1

MA1M

IF1M

HALL 2

REVERB

VOLUME

CONTROL

ON OFF

POWER

MIN MAX

BRILLIANCE

MELLOW BRIGHT

CN2M CN1M

TONE

PIANO 2 E.PIANO HARPSICHORD PIPE ORGAN STRINGS CHOIRVIBRAPHONE W.BASS E.BASS

PIANO 1

LOWER TONE

HALL 1

TREMOLO

STAGE

CHORUS

SONG A

ROOM

SONG B RECORD

TUNE DEMO

MEMORY

START/ STOP

CN3M

TP10-KY1M TP10-KY2M

MA4M MA5M

Note: IF1M PCB is a terminal board for the keyboard PCBs, and included in the main PCB.

Main PCB

Jack PCBs

PCB

MA1M

MA2M

JCM433-

Components

CPU, DSP, Sound Source ROM Working storage RAM, Effect RAM Reset IC, DAC, Filter, Key controller, Power amp, Power supply circuit

LINE IN/OUT jack, MIDI jacks

Console PCBs

Power PCB

MA4M MA5M CN1M

CN2M CN3M PS1

Phone jacks Power indicator Gate array (Button controller/LED driver), LEDs,

Buttons Main Volume, Brilliance volume Tune Buttons, Demo button Fuse, Noise filter

— 5 —

DISASSEMBLY INSTRUCTIONS

1. Disassembling top board

1-1. Remove 8 screws on the rear. 1-2. Slide the top board towards the rear.

The top board will be free from catches on the case.

1-3. Lift the top board.

For keyboard-cover model

2. Disassembling keyboard cover

2-1. Slide the keyboard cover to open fully. 2-2. Passing the gear into the opening on each

rack, lift the keyboard cover.

For no-keyboard-cover model

2. Disassembling the front cover

2-1. Remove 4 screws at both ends of the front cover. 2-2. Remove the front cover.

— 6 —

3. Disassembling console panel

Note: To avoid scratch on the side board, put paper between the

console panel and the side board at both ends.

3-1. The console panel is fixed with screws and nuts. Holding the

nut, remove the screw. 3-2. Remove the screw fixing a grounding wire at the transformer. 3-3. Slide the console panel towards the front to free from catches. 3-4. Turn round the console panel. 3-5. Remove the 2 screws fixing the power switch.

Insert paper here.

4. Disassembling front cover

4-1. Remove 5 screws at the front edge on the bottom. 4-2. Disconnect the connector for phone jacks from the main PCB. 4-3. Watching the phone-jack cable, pull out the front cover towards the front.

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5. Disassembling keyboard unit

5-1. Remove 6 screws at both ends on the bottom, and a screw at the middle.

5-2. Remove 2 screws at both ends of keyboard unit.

5-3. Disconnect 2 connectors for the keyboard unit from the main PCB. 5-4. Moving the keyboard unit towards the front, remove the unit from the case.

6. Disassembling keys

6-1. Peel the red felt and sponges off the keyboard unit. 6-2. Using a long-nose plier, remove key springs. 6-3. Pressing the hook with a long-nose plier. Lift the key.

— 8 —

7. Disassembling keyboard PCBs

7-1. Turn round the keyboard unit to face the PCB

up. 7-2. Disconnect the connector at the middle of

keyboard. 7-3. Remove screws on the keyboard PCBs.

8. Replacing the main PCB

Note: The main PCB contains a lithium battery for memory back-up. Please remove the jumper

before replacing the PCB. And make sure that the jumper is reset on new main PCB after replacing the PCB. Because no jumper is set on a spare part of the main PCB.

Jumper

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