Casio LK-125 Troubleshooting guide

LK-125

SEP. 2010

LK-125

Ver. 2 : Jan. 2012

ELECTRONIC KEYBOARD

CONTENTS

SPECIFICATIONS........................................................................................... 1

BLOCK AND WIRING DIAGRAM .................................................................. 2

PCB INFORMATION....................................................................................... 3

CIRCUIT DESCRIPTION ................................................................................ 4

PRINTED CIRCUIT BOARDS......................................................................... 5

DISASSEMBLY............................................................................................... 7

DIAGNOSTIC PROGRAM ............................................................................ 16

EXPLODED VIEW......................................................................................... 22

PARTS LIST.................................................................................................. 23

SCHEMATIC DIAGRAMS............................................................................. 26

LK-125

– 1 –

SPECIFICATIONS

Keyboard 61 standard-size keys; 5 octaves

Key Light System Can be turned on and off (up to 4 keys can be lit at the same time)

Tones 100 presets

Polyphony 12 notes maximum

3-Step Lesson System Number of simultaneously lit keys; 4

3-Steps

Playback 1 tune repeat playback

Voice Fingering Guide On/Off

Auto-accompaniment

Rhythm Patterns 50 presets

Tempo Adjustable, (216 steps, = 40 to 255), initial value; 120

Chords Two systems; CASIO CHORD, FINGERED

Other Fill-in pattern, Synchro start

Song Bank Tunes 100 tunes

Musical Information Function Tone, Auto Accompaniment, Song Bank numbers and names; tempo,

3 step lesson display, chord name, ngering, timing indicator, key lighting,

voice ngering

Other Functions

Transpose F# to C to F: half-note

Tuning Adjustable A4 = Approx. 440 Hz ± 50 cents,

Initial value: A4 = Approx. 440 Hz

Speakers 10 cm diameter × 2 (Output: 2 W + 2 W)

I/O Terminals

Power Supply DC 9.5 V jack

Headphones/Output Stereo standard jack (Output is monaural.)

Output impedance 78 Ω, output voltage: 4 V (RMS) MAX

Power Supply 2-way

Batteries 6 AA-size zinc-carbon batteries or alkaline batteries

Battery Life:

Approximately 4 hours continuous operation on alkaline batteries

Approximately 1 hour continuous operation on zinc-carbon batteries

AC Adaptor AD-E95100L

Auto Power Off Approximately 6 minutes after the last operation

Power Consumption 9.5 V 7.7 W

Dimensions 94.9 × 30.4 × 9.3 cm (37 3/8× 11 15/16 × 3 11/16 inch)

Weight Approximately 3.4 kg (7.5 lbs) (without batteries)

LK-125

– 2 –

BLOCK AND WIRING DIAGRAM

VD5

VE5

RIGHT

SPEAKER

LEFT

SPEAKER

VE5

VA5

VD5

VCP

D202

LSP

RSP

VA5 VE5

VD5 VA5

VE5

LCD

VCP

KEYBOARD

PCB

(M800-KYA2)

KEYBOARD LED PCB

(M821-LDA2)

KEYBOARD LED PCB

(CSM446-LD5M)

KEYBOARD LED PCB

(M821-LDA1)

KEYBOARD PCB

(M800-KYA1)

LCD

CONTROLLER

IC3

KEYBOARD LED

CONTROLLER

IC2

POWER

AMPLIFIER

IC201

RESET IC

IC4

POWER SUPPLY

CIRCUIT

Q202, Q203, Q204,

D206, D207,

C225-C229

CN3 (17 pin)

CN201 (17 pin)

CN205

CN206CN207

CN6

CN8

CN204

LSP+

LSP-

CN9

CN7

CN4

CN5

RSP+

RSP-

CN803 (16 pin)

CN801 (13 pin)

CN802 (13 pin)

CN1 (16 pin) CN2 (16 pin)

CN506 (16 pin) CN503 (12 pin)

CN504 (6 pin) CN504 (6 pin)CN505 (6 pin)

JE (6 pin)

KEYBOARD LED PCB

(CSM446-LD4M)

JF (6 pin)

KEYBOARD LED PCB

(CSM446-LD3M)

JG (6 pin)

CN501 (12 pin)

SI1, SI2, SI4~SI6,

KI7S, SO1~SO6

KI0~KI7 KO0~KO7 LY0~LY7, LX0~LX7

KI4S~KI7S,

KO11S

PHONES/OUTPUT

(J202)

9 V

DC IN

(J201)

POWER AMP PCB (M820-PSA1)

MAIN PCB

(M821-MDA1)

BUTTONS VOLUME

(SW202)

POWER

SWITCH

(SW201)

POWER OFF

CIRCUIT

Q201

MPU

IC1

BUTTONS

KI0S~KI7S,

KO8S~KO11S

RESET

A0~A2

DB0~DB3

DB4~DB7

CN202 (-)

CN203 (+) BATTERY

LK-125

– 3 –

PCB INFORMATION

M820-PSA1 M800-KYA2M800-KYA1 M821-MDA1

CSM446-LD5

M821-LDA2M821-LDA1

CSM446-LD3 CSM446-LD4

Classiﬁ cation Parts Name PCB Name Components

Main PCB PCB ASSY/MDA1 M821-MDA1

MPU, LCD Controller, Keyboard LED

Controller, Reset IC, Buttons,

Right Speaker Terminal

Power Amp PCB PCB ASSY/PSA1 MX820-PSA1

Power Supply Circuit, Power Ampli er,

Power Switch, Volume, Buttons,

DC 9.5 V Jack, Left Speaker Terminal,

Phones/Output Jack

Keyboard LED

PCB

PCB ASSY/LDA M821-LDA1

Keyboard LED

M821-LDA2

PCB ASSY/LD3M CSM446-LD3M

PCB ASSY/LD4M CSM446-LD4M

PCB ASSY/LD5M CSM446-LD5M

Keyboard PCB PCB ASSY/KYA M800-KYA1 Keyboard

M800-KYA2

LK-125

– 4 –

CIRCUIT DESCRIPTION

KEY MATRIX



KC0 KC1 KC2 KC3 KC4 KC5 KC6 KC7

KI0 C2 C2# D2 D2# E2 F2 F2# G2

KI1 G2# A2 A2# B2 C3 C3# D3 D3#

KI2 E3 F3 F3# G3 G3# A3 A3# B3

KI3 C4 C4# D4 D4# E4 F4 F4# G4

KI4 G4# A4 A4# B4 C5 C5# D5 D5#

KI5 E5 F5 F5# G5 G5# A5 A5# B5

KI6 C6 C6# D6 D6# E6 F6 F6# G6

KI7 G6# A6 A6# B6 C7

NOMENCLATURE OF KEYS



C3 C4 C5

C6 C7

BUTTON MATRIX



KO8S KO9S KO10S KO11S

KI0S 0 5 TONE STEP 1

KI1S 1 6 RHYTHM STEP 2

KI2S 2 7 SONG BANK STEP 3

KI3S 3 8 PART SELECT SPEAK

KI4S 4 9 ONE KEY PLAY

LEFT

FINGERED

(POWER/MODE)

KI5S START/STOP TEMPO DOWN/

VALUE

ONE KEY PLAY

RIGHT

CASIO CHORD

(POWER/MODE)

KI6S TEMPO UP/

VALUE KEY LIGHT NORMAL

(POWER/MODE)

KI7S SYNCHRO/

FILL-IN DEMO OFF

(POWER/MODE)

LK-125

– 5 –

PRINTED CIRCUIT BOARDS

Main PCB: M821-MDA1 Power Amp PCB: M820-PSA1

LK-125

– 6 –

Keyboard PCB: M800-KYA1

Keyboard LED PCB: M821-LDA1

Keyboard PCB: M800-KYA2

LK-125

– 7 –

DISASSEMBLY

CAUTION



The photos show a prototype. The appearance of the instrument, such as color, may

z

differ from the actual model.

To avoid damages to the instrument and the oor, lay the instrument on a mattress

z

or blanket before starting disassembling.

There are several kinds of screws. Be sure to use the correct type of screws when

z

reassembling. It is advisable to sort the screws as shown below after removing

them.

If a screw cap is attached to a screw, be sure to reattach the screw cap when

z

reassembling.

BEFORE STARTING REPAIR OR SERVICING



Remove the AC adaptor or the AC cord.

z

Remove accessories such as the music stand.

z

LK-125

– 8 –

DISASSEMBLY



PANEL UNITA.

Undo 11 screws on the bottom surface of the main unitA-1.

When replacing the keyboard LED PCBs, undo 16 screws and then remove the L-COVER-A/B/C.A-2.

L-COVER-C L-COVER-B L-COVER-A

To install the L-COVER-A/B/C, tighten the screws indicated with arrows engraved on each cover

rst.

L-COVER-C L-COVER-B L-COVER-A

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