Yamaha Dx21 User manual

DIGITAL

PROGRAMMABLE

ALGORITHM

SYNTHESIZER

DX21

SERVICE

MANUAL

■

CONTENTS

IMPORTANT

NOTICE.

1

SPECIFICATIONS.

1

PANEL

LAYOUT.

2

TEST

PROGRAMS.3/4

BASIC

CIRCUIT

OPERATIONS.

5

TABLE

OF

1C

FUNCTIONS.

6

MIDI

DATA

FORMAT.7

~

17

CIRCUIT

BOARDS

.18~21

BLOCK

DIAGRAM

.

22

PARTS

LIST

OVERALL

ASSEMBLY

.23/24

KEYBOARD

ASSEMBLY.

25

LCD

ASSEMBLY

&

WHEEL

ASSEMBLY.

26

CIRCUIT

BOARDS

&

ELECTRICAL

PARTS

.27~29

OVERALL

CIRCUIT

DIAGRAM.

30

006667

NIPPON

GAKKI

CO.,

LTD.

HAMAMATSU,

JAPAN

2.93K-403

(HI

®

Printed

in

Japan

’85.6.

DX21

IMPORTANT

NOTICE

This

manual

has

been

provided

for

the

use

of

authorized

Yamaha

Retailers

and

their

service

personnel.

It

has

been

assumed

that

basic

service

procedures

inherent

to

the

industry,

and

more

specifically

Yamaha

Products,

are

already

known

and

understood

by

the

users,

and

have

therefore

not

been

restated.

WARNING:

Failure

to

follow

appropriate

service

and

safety

procedures

when

servicing

this

product

may

result

in

personal

injury,

destruction

of

expensive

components

and

failure

of

the

product

to

perform

as

specified.

For

these

reasons,

we

advise

all

Yamaha

product

owners

that

all

service

required

should

be

performed

by

an

authorized

Yamaha

Retailer

or

the

appointed

service

representative.

IMPORTANT:

The

presentation

or

sale

of

this

manual

to

any

individual

or

firm

does

not

constitute

authorization,

certification,

recognition

of

any

applicable

technical

capabilities,

or

establish

a

principle-agent

relationship

of

any

form.

The

data

provided

is

believed

to

be

accurate

and

applicable

to

the

unit(s)

indicated

on

the

cover.

The

research,

engineering,

and

service

departments

of

Yamaha

are

continually

striving

to

improve

Yamaha

products.

Modifications

are,

therefore,

inevitable

and

changes

in

specification

are

subject

to

change

without

notice

or

obligation

to

retrofit.

Should

any

discrepancy

appear

to

exist,

please

contact

the

distributor’s

Service

Division.

WARNING:

Static

discharges

can

destroy

expensive

components.

Discharge

any

static

electricity

your

body

may

have

accumulated

by

grounding

yourself

to

the

ground

buss

in

the

unit

(heavy

gauge

black

wires

connect

to

this

buss).

IMPORTANT:

Turn

the

unit

OFF

during

disassembly

and

parts

replacement.

Recheck

all_

work

before

you

apply

power

to

the

unit.

■

SPECIFICATIONS

Keyboard

.

61

keys,

Ci

~

C6

Sound

Source

.

FM

Tone

Generator:

4

operators

x

2

(A,B),

8

Algorithms

Simultaneous

Note

Output

Polyphonic:

8

notes

(SINGLE),

4

notes

(DUAL),

4

+

4

notes

(SPLIT)

Monophonic:

1

note

(SINGLE,

DUAL),

1

+

1

note

(SPLIT)

Internal

Memory

.

128

ROM

voice

memory

32

RAM

voice

memory

32

RAM

performance

memory

Controls

.

PITCH

BEND

WHEEL,

MODULATION

WHEEL,

VOLUME,

BALANCE,

DATA

ENTRY

Display

.

LCD

(16

characters

x

2

tines)

Connecting

Terminals

.

OUTPUT

MIX/A,

OUTPUT

B,

PHONES,

CASSETTE

Control

Terminals

.

FOOTSWITCH

(SUSTAIN,

PORTAMENTO),

FOOT

CONTROLLER

(VOLUME),

MIDI

(IN,

OUT,

THRU)

Dimensions/Weight

.

909

(W)

x

82

(H)

x

270

(D)

mm

(35.8"

x

3.2"

x

10.6")

8

kg

(17.6

lbs)

Power

Requirements

.

U.S.

&

Canadian

Models:

120

V,

50/60

Hz

General

Models:

220

~

240

V,

50

Hz

Power

Consumption

.

7

W

Standard

Accessories

.

Music

Stand,

Cassette

Cable

Optional

Accessories

1

FC7

Foot

Controller,

FC4

or

FC5

Footswitch,

BC1

Breath

Controller,

LC-21S

or

SC-21

Carrying

Case,

LG-21

Stand,

MIDI-03

or

MIDI-15

MIDI

Cable

•

Control

Panel

DX21

■

TEST

PROGRAMS

NOTE:__

When

the

test

program

is

executed,

data

in

the

performance

memory

will

be

initialized.

Please

write

down

the

data

to

the

performance

data

table

before

executing

the

program.

BEFORE

ENTERING

THE

TEST

MODE

OF

THE

DX21,

IT

IS

RECOMMENDED

THAT

YOU

READ

THROUGH

THE

TEST

PROGRAM

PROCEDURES.

.

TEST

2

REQUIRES

THE

CONNECTION

OF

EXTER¬

NAL

DEVICES

AND

IT

MAY

HELP

TO

MAKE

THE

CONNECTIONS

AND

ADJUSTMENTS

OF

THIS

TEST

PRIOR

TO

ENTERING

THE

TEST

MODE.

Test

Mode

Entry

Procedure

To

enter

the

internal

test

mode

of

the

DX21,

turn

the

power

switch

on

while

depressing

the

voice

buttons

I

1

l

a

nd

[

2

|

o

n

the

side

A.

Release

buttons

j

1

|

a

nd

|

2

|

o

nce

characters

are

displayed

on

the

LCD.

The

unit

will

then

display

the

ROM

version

message

and

auto¬

matically

go

to

the

first

test

or

check.

TEST

1:

ROM

version

message

and

level

check

After

initiating

the

Test

Mode,

the

unit

displays

the

message

shown

below.

VI.

s

05-rVlar—85

Check

Level

The

first

line

of

the

LCD

display

indicates

the

ROM

version

number

(VI.

2)

and

the

date

of

that

version.

The

second

line

of

the

display

indicates

that

the

unit

is

in

the

Level

Verification

Mode.

Sine

waves

of

440Hz

are

output

from

each

output

jack

when

the

volume

is

at

its

maximum

level.

The

table

shown

below

has

the

necessary

information

to

check

or

verify

each

output

level.

Output

Jack

Level

Load

OUT

A,

B

—22dBm

10K

PHONES

R,

L

—13dBm

47

Before

proceeding

to

the

TEST

2,

please

read

the

instructions

of

that

test.

After

reviewing

the

test

procedure,

depress

the

1

+

1

button

to

initiate

the

test.

TEST

2:

Check

of

RAM,

MIDI

I/O,

and

Cassette

I

nterface

Before

initiating

this

test

make

the

following

connec¬

tions

as

indicated

below:

1.

Connect

MIDI

IN

and

OUT

with

a

MIDI

cable.

2.

Connect

the

cassette

OUT

jack

to

the

input

of

an

amplifier

and

connect

the

output

of

the

amplifier

to

the

cassette

IN

jack.

SPECIAL

INSTRUCTIONS:

*A

mixer

or

stereo

cassette

deck

can

be

used

as

this

amplifier

stage.

This

amplifier

is

essentially

inserted

in

the

cassette

OUT

and

IN

path.

The

mixer

or

stereo

cassette

deck

(in

the

REC/

PAUSE

mode)

must

be

adjusted

to

have

a

gain

of

approximately

10dB.

This

gain

adjustment

should

be

made

before

entering

the

Test

Mode.

To

make

this

gain

adjustment

access

the

CASSETTE

SAVE

function

of

the

DX21

and

initiate

the

SAVE

function

by

depressing

the

|

+1

1

button

twice.

The

Voice

information

of

the

DX21

is

then

transmitted

from

the

Cassette

OUT

jack

and

has

an

approximate

level

of

—28dB.

Therefore,

connect

a

level

meter

to

the

output

of

the

amplifier

stage

and

adjust

the

output

level

to

approximately

—18dB

(a

10dB

gain).

Now

the

amplifier

gain

is

adjusted

to

perform

the

Cassette

OUT/IN

test.

When

you

initiate

TEST

2

by

depressing

the

|

+1

|

button,

this

test

automatically

executes

the

RAM,

MIDI

I/O,

and

cassette

OUT/IN

interface

checks.

If

no

ERRORS

are

detected

then

the

test

routine

auto¬

matically

sequences

to

TEST

3,

the

LCD

Test.

If

the

RAM

is

bad

the

LCD

display

will

indicate

which

1C

is

bad,

providing

that

the

malfunctioning

RAM

1C

does

not

cause

a

system

operation

problem.

If

there

is

a

malfunction

of

the

MIDI

OUTPUT

or

INPUT,

the

LCD

display

indicates

ERROR

MIDI!

Also,

it

should

be

noted

that

if

the

MIDI

test

was

checked

by

another

technician

the

correct

MIDI

data

may

already

be

stored

in

the

MIDI

BUFFER.

There¬

fore,

if

you

initiate

the

MIDI

test

with

no

MIDI

cable

plugged

in

it

will

still

pass

the

test

with

no

ERROR.

You

can

CLEAR

the

MIDI

buffer

by

connect

the

cable

and

play

the

keyboard

in

the

normal

operating

mode.

This

procedure

will

store

different

MIDI

data

into

the

MIDI

BUFFER.

If

the

cassette

OUTPUT,

INPUT

or

the

inserted

amplifier

stage

malfunctions,

the

LCD

display

will

indicate

ERROR

CASS.!

TEST

3:

LCD

Check

This

test

checks

the

LCD

display.

All

dots

on

the

LCD

should

flash.

Verify

that

each

dot

flashes.

Before

proceeding

on

to

TEST

4,

the

A/D

and

foot-

switch

test,

connect

the

BC-1,

FC-7,

and

two

FC-4s

to

all

BREATH,

VOLUME,

SUSTAIN,

and

PORTA¬

MENTO

jacks.

Then

depress

|

+1

|

for

approximately

one

second

to

proceed

to

TEST

4.

DX21

TEST

4:

A/D

and

Footswitch

check

For

this

test

you

operate

the

controls

as

indicated

by

the

LCD

display.

Once

the

control

is

operated

throughout

its

range

LCD

display

will

indicate

the

that

to

be

checked.

If

a

control

or

controller

is

malfunctioning

then

the

test

will

not

advance

to

the

It

should

also

be

noted

that

all

controls

and

controllers

must

be

checked

for

the

Test

Routine

continue

on

to

the

This

test

checks

the

following

controls

and

controllers

listed

below:

1.

The

PITCH

BEND

control

2.

The

MOD.

WHEEL

control

3.

The

DATA

ENTRY

control

4.

The

FOOT

VOL.

controller

5.

The

BREATH

controller

6.

The

SUSTAIN

footswitch

7.

The

PORTAMENTO

footswitch

The

test

routine

automatically

increments

to

the

TEST

5,

once

all

checks

have

been

completed.

TEST

5:

Keyboard

check

Test

5

checks

the

keyboard

contacts.

The

LCD

dis¬

plays

the

keys

to

be

depressed

and

once

the

key

is

depressed

and

released

the

LCD

will

indicate

the

to

be

depressed.

No

error

message

occurs

when

a

key

contact

is

bad

or

a

key

is

depressed

in

error.

Once

all

key

contacts

have

been

verified

by

depressing

and

releasing

the

appropriate

keys,

the

Test

Routine

advances

to

TEST

6,

the

Panel

Switch

check.

TEST

6:

Panel

Switch

check

For

this

test,

press

the

switch

indicated

by

the

LCD

display.

The

numbering

order

of

the

panel

switch

sequence

is

shown

below.

After

the

panel

switch

test

has

been

completed,

the

test

routine

automatically

exits

the

Test

Mode

and

the

unit

returns

to

its

normal

operating

mode.

4

DX21

■

BASIC

CIRCUIT

OPERATIONS

1.

The

Main

Clock

Circuit

The

clock

generation

circuit

for

the

CPU

and

soud

generation,

generates

a

signal

having

a

frequency

of

7.15909MHz.

The

signal

of

7.15090MHz

is

applied

to

the

EXTAL

of

the

CPU,

and

divided

by

a

factor

of

4

inside

the

CPU

to

create

the

system

clock.

A

signal

having

a

frequency

of

3.58MHz

is

used

for

sound

generation.

2.

The

Sub-Clock

Circuit

This

clock

circuit

generates

a

signal

of

500kHz

for

A/D

conversion

and

the

MIDI

clock.

The

500kHz

clock

signals

are

applied

to

22

of

the

CPU,

which

in

turn

is

divided

by

a

factor

of

16

inside

the

CPU

to

create

the

31.25kHz

MIDI

clock.

3.

The

Reset

Circuit

A

reset

signal

is

generated

an

RC

network

and

Schmitt

Trigger

invertor

1C.

A

reset

1C

is

used

to

short

any

remaining

voltage

of

the

10

microfarad

charging

capacitor

to

ground

on

power-up.

Then

the

reset

1C

goes

to

a

high

impedance

state

to

allow

the

capacitor

to

charge

via

a

resistor

con¬

nected

to

the

+5V

supply.

Therefore,

initially

the

reset

signal

is

a

logic

"LOW"

level

until

the

capacitor

reaches

the

threshold

of

the

Schmitt

Trigger

Invertor

ICs

and

then

the

reset

signal

switches

to

a

"HIGH"

logic

level.

The

reset

signal

is

also

fed

to

two

transistors.

One

transistor

controls

the

Battery

Back-Up

circuit

and

the

other

control

the

CHIP

SELECT

2

signal

for

the

RAM

ICs.

The

CHIP

SELECT

2

or

CE2

signals

disables

the

RAM

ICs

so

they

will

not

be

selected.

This

eliminates

the

possibility

of

the

RAM

ICs

being

accessed

and

accidentally

written

to.

4.

The

CPU,

ROM

and

RAM

•

The

CPU

with

clock

input

of

7.15909MHz,

operates

with

a

system

clock

of

approximately

1.8MHz.

The

access

time

for

the

ROM,

RAM,

and

other

components

connected

to

the

bus

must

be

faster

as

the

read/write

pulse

width

is

approximately

260nS.

•

The

ROM

is

allocated

from

addresses

$8000

to

$FFFF

of

the

memory,

with

$8000

to

$A480

being

the

area

for

the

128

voice

data,

and

$A480

to

$FFFD

being

the

program

area.

The

use

of

two

128K

bytes

ROM

is

possible.

In

this

case,

jumper

*1

is

moved

to

*2,

and

IC36

is

installed.

•

The

RAM

is

allocated

from

addresses

$1000

to

$27

FF

of

the

memory

with

the

area

from

$1000

to

$

191F

used

as

the

voice

memory

area,

and

the

area

from

$1920

and

above

is

used

for

the

various

stacks

and

registers.

Furthermore,

the

entire

area

is

memory

backed

up

by

a

battery

to

enable

the

memory

to

be

retained

after

the

power

is

turned

off.

5.

The

Address

Map

The

CPU

addresses

are

as

follows:

$00

$1F

Internal

CPU

registers

and

ports

$20

A/D

output

port

$22

A/D

start

$24

OPM

$26

LCD

$28,$29

CHORU5

ON-OFF

$40

~

$FF

RAM

in

CPU

$1000

~$27EF

RAM

$8000~$FFFF

ROM

6.

The

A/D

Circuit

The

A/D

circuit

uses

an

8

bit

8

channel

ADC

1C.

Five

of

the

eight

input

channels

are

used.

When

a

channel

number

and

start

pulse

are

received

from

CPU,

conversion

is

performed

for

that

channel.

The

CPU

is

notified

of

the

completed

conversion

when

it

receives

the

EOC

signal

from

the

ADC

1C.

The

CPU

outputs

the

OE

signal

after

detection

of

EOC,

and

data

is

fetched

from

the

data

bus.

7.

The

Sound

Generation

Circuit

This

circuit

consists

of

4

function

operator

with

8

note

capability.

The

FM

tone

generator

or

operator

and

the

DAC,

generate

the

FM

tones

based

on

data

from

the

CPU.

There

are

two

channels

for

audio

output,

and

different

voices

are

possible

on

each

channel.

8.

The

Chorus

Circuit

This

is

a

phase

modulation

circuit

with

a

128

stage

BBD.

The

effect

is

turned

on/off

by

the

CPU.

9.

The

HP

Circuit

This

is

an

amplification

circuit

for

the

headphones

which

allows

use

of

headphones

having

an

im¬

pedance

of

8

to

150

ohms.

10.

The

Switch

Scan

Circuit

The

switch

scan

circuit

is

connected

directly

to

the

CPU

and

is

capable

of

scanning

128

(8

x

16)

switches.

With

the

DX21,

61

Keyboard

switches

and

42

panel

switches

are

scanned,

for

a

total

of

103

switches.

11.

The

MIDI

circuit

The

MIDI

circuit

is

connected

directly

to

the

CPU

and

has

IN,

OUT,

and

THRU

OUT

terminals,

and

meets

MIDI

standards

VI.

0.

12.

The

Cassette

Interface

Circuit

The

cassette

interface

circuit

connected

is

also

directly

to

the

CPU

and

runs

the

cassette

I/O

at

a

rate

of

1200

baud

which

is

controlled

by

the

CPU

software.

5

DX21

■

TABLE

OF

1C

FUNCTIONS

YM2164

OPP

1

Name

I/O

____________----—

Function

Remarks

Vss

-

GND

'

.I.

IRQ

1RQ

output

port

mm

7c

1

"L"

reset

input

(Active

Low)

Ao

1

Internal

register

selection

signal

input

WT

1

Data

write

request

input

from

CPU

RD

1

Data

read

request

input

from

CPU

•

CS

1

Chip

selection

input

CTl

0

Filter

characteristics

switch

or

control

signal

output

for

voice

synthesizing

CJ2

0

"

D„

I/O

3-state

data

bus

I/O

port

Vss

-

GND

0,

I/O

Bgfli

t

r

3-state

data

I/O

port

■

|fl||B

d

7

I/O

J

SH2

0

T

rnimmi

SHI

0

J

Signal

output

for

L/R

separation

21

So

0

Sound

generation

serial

data

(L/R)

22

Vcc

-

Power

+5V

01

0

Clock

output

for

DAC

synchronization

0M

1

CPU

master

clock

input

for

synchronization

with

CPU

YM3012

DAC

No.

Name

I/O

Remarks

1

Vcc

-

+5V

2

CLOCK

1

Timing

clock

input

for

synchronization

with

OPP

3

GND

-

Digital

GND

IIIIII

DATA

1

Voice

serial

data

input

SAM

1

Data

input

for

sampling

(for

L/R

separation)

6

SAM

2

1

(

"

)

ICL

1

Initial

clear

input

§$0$%

GND

-

Analog

GND

CH

1

0

CHI

(L

ch)

analog

signal

output

WMMii$.

CH

2

0

CH2

(R

ch)

COM

1

L/R

Separation

input

To

BUF

0

DAC

Analog

output

pll

j

Mid.

Point

1

Reference

voltage

input

of

analog

signal

W&MA

BC

0

Bias

compensation

15

RB

0

1/2

Vcc

bias

regulator

output

16

GND

-

6

DX21

■

MIDI

DATA

FORMAT

1.

Transmission

Conditions

ACTIVE

SENSING

NOTE

OFF

NOTE

ON

SUSTAIN

SWITCH

PITCH

BENDER

MODULATION

WHEEL

BREATH

CONTROL

DATA

ENTRY

SLIDER

VOLUME

PORTAMENTO

SWITCH

PROGRAM

CHANGE

PARAMETER

CHANGE

I

VOICE

BULK

32

VOICE

BULK

$FO,

$43,

$On,

$04

2.

Transmission

Data

All

MIDI

data

is

transmitted

when

the

MIDI

ON/OFF

function

is

ON.

The

MIDI

transmission

channel

is

determined

by

the

setting

of

the

MIDI

TRNS

CH

function.

2-1.

CHANNEL

INFORMATION

2-1-1.

Channel

Voice

Message

(1)

Key

Off

Status

lOOOnnnn

n=channel

no.

Note

no.

Okkkkkkk

k=36(C1)

~

96(C6)

Velocity

01000000

DX21

(2)

Key

On

Status

1OOOnnnn

n=channel

no.

Note

no.

Okkkkkkk

k=36(C1)

~

96(C6)

Velocity

01000000

Control

Change

Status

1011nnnn

n=channel

no.

Control

no.

Occccccc

Control

code

Ovvvvvvv

a)

Transmitted

whether

MIDI

CH

INFO

is

ON

or

OFF

Control

no.

Control

code.

C=64:

Sustain

sw.

V=0:OFF

(

127:ON

b)

Transmitted

when

MIDI

CH

INFO

is

ON

Control

No.

C=1:

modulation

wheel

C=2:

breath

control

C=6:

data

entry

slider

C=7:

foot

volume

C=65:

portamento

sw.

Control

code

V=0~127

V=0:OFF,

127:ON

(4)

Program

Change

Status

llOOnnnn

n=channel

no.

Program

no.

Oppppppp

p=0~31

This

data

is

transmitted

when

a

voice

selector

is

pressed

during

the

play

mode,

when

MIDI

CH

INFO

is

ON

and

MIDI

SYS

INFO

is

OFF.

Also

transmitted

when

a

performance

selector

is

pressed

in

the

performance

mode.

(5)

Pitch

Bend

Status

IllOnnnn

Code(LSB)

Ouuuuuuu

Code

(MSB)

Ovvvvvvv

The

transmitted

data

is

as

follows:

MSB

00000000

01000000

01111111

LSB

00000000

01111110

n=channel

no.

Lowest

value

Center

value

Highest

value

2-2.

SYSTEM

INFORMATION

2-2-1.

System

Real-time

Message

Active

sensing

Status

11111110

Transmitted

once

approximately

every

200

milliseconds

2-2-2.

System

Exclusive

Message

Trasnmitted

only

when

MIDI

SYS

INFO

is

ON

8

DX21

(1)

Parameter

Change

Status

11110000

ID

no.

01000011

Substatus/ch.

no.

0001nnnn

n=channel

no.

Parameter

group

no.

00010010

Perameter

no.

Oppppppp

Data

Oddddddd

EOX

11110111

This

data

is

transmitted

when

voice

or

function

parameters

are

changed

in

the

EDIT

or

FUNCTION

modes.

The

voice

parameters

transmitted

are

those

given

in

voice

parameter

table

5-2,

and

the

function

parameters

transmitted

are

shown

in

function

parameter

table

5-3.

(2)

1

Voice

Bulk

Data

Status

11110000

ID

no.

01000011

Substatus/ch.

no.

OOOOnnnn

n=channei

no.

Format

no.

00000011

Byte

count

00000000

Byte

count

01011101

Data

Oddddddd

j

1

93

bytes

Oddddddd

Checksum

Oeeeeeee

EOX

11110111

The

data

for

one

voice

is

transmitted

when

a

voice

selector

is

pressed

in

the

PLAY

SINGLE

mode.

Data

in

the

voice

edit

buffer

is

transmitted

when

a

format

no.

f=3

dump

request

is

received.

The

transmitted

data

is

showm

in

voice

parameter

table

5-2.

The

checksum

is

the

lowest

7

bits

of

the

two's

complement

sum

of

all

data

bytes

(the

same

applies

below).

(3)

32

Voice

Bluk

Data

Status

11110000

ID

no.

01000011

Substatus/ch.

no.

OOOOnnnn

n=channel

no.

Format

no.

00000100

Byte

count

00100000

Byte

count

00000000

Data

Oddddddd

1

4096

bytes

Oddddddd

Checksum

Oeeeeeee

EOX

11110111

The

data

of

all

32

voices

in

RAM

memory

will

be

transmitted

if

the

YES

(or

BULK)

key

is

pressed

in

response

to

the

"MIDI

Transmit?"

display

which

appears

when

the

BULK

key

is

pressed

in

the

FUNCTION

mode.

The

data

for

all

32

voices

will

also

be

transmitted

when

a

format

no.

f=4

dump

request

is

received.

The

transmitted

data

is

shown

in

voice

data

table

5-1.

55

bytes

of

0's

are

added

to

the

73

bytes

in

this

table,

so

128

bytes

are

transmitted

for

each

voice.

4096

bytes

are

therefore

transmitted

for

all

32

voices.

9

Yamaha DX21 User manual

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