Casio LK-127 Troubleshooting guide

LK-127
MAR. 2013

LK-127
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............................................................................. 27

LK-127
– 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, 2= 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-127
– 2 –
BLOCK AND WIRING DIAGRAM
VD5
VE5
VC
RIGHT
SPEAKER
LEFT
SPEAKER
VE5VA5VD5
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)
DC 9 V
(J201)
POWER & AMP PCB (M820-PSA1)
MAIN PCB
(M821-MDA1)
BUTTONS VOLUME
POWER
SWITCH
POWER OFF
CIRCUIT
Q201
MPU
IC1
BUTTONS
KI0S~KI7S,
KO8S~KO11S
RESET
RESET
A0~A2
DB0~DB3
DB4~DB7
CN202 (-)
CN203 (+) BATTERY

LK-127
– 3 –
PCB INFORMATION
M820-PSA1 M800-KYA2M800-KYA1 M821-MDA1
CSM446-LD5M
M821-LDA2M821-LDA1
CSM446-LD3M CSM446-LD4M
Parts Name PCB Name Functions
MAIN PCB
PCB UNIT/MAIN M821-MDA1 MPU, LCD controller, Keyboard LED controller, Reset IC,
Buttons, Right speaker
POWER & AMP PCB
PCB UNIT/
POWER & AMP MX820-PSA1 Power supply circuit, Power ampli er, Power switch, Volume, Buttons, DC 9.5 V jack, Left speaker, PHONES/OUTPUT jack
KEYBOARD PCB
PCB UNIT/KYA M800-KYA1 Keyboard
M800-KYA2
KEYBOARD LED PCB
PCB UNIT/LDA M821-LDA1
Keyboard LED
M821-LDA2
PCB UNIT/LD3 CSM446-LD3M
PCB UNIT/LD4 CSM446-LD4M
PCB UNIT/LD5 CSM446-LD5M

LK-127
– 4 –
CIRCUIT DESCRIPTION
 Nomenclature of Keys
C2 C3 C4 C5 C6 C7
 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
 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-127
– 5 –
PRINTED CIRCUIT BOARDS
MAIN PCB: M821-MDA1 POWER & AMP PCB: M820-PSA1

LK-127
– 6 –
KEYBOARD PCB: M800-KYA1
KEYBOARD PCB: M800-KYA2
KEYBOARD LED PCB: M821-LDA1
KEYBOARD LED PCB: M821-LDA2

LK-127
– 7 –
DISASSEMBLY
 About Repair
• The photos show a prototype. The appearance of the instrument, such as color, may differ
from the actual model.
• Toavoiddamagestotheinstrumentandoor,laytheinstrumentonamattressorblanket
beforestartingdisassembling.
• Thereareseveralkindsofscrews.Besuretousethecorrecttypeofscrewswhen
reassembling.Itisadvisabletosortthescrewsasshownbelowafterremovingthem.
• Ifascrewcapisattachedtothescrew,removeit.Besuretoreattachthescrewcapwhen
assembling.
• Checkhowcablesarewiredbeforeremovingcables.Besuretowirethecablesinthesame
mannerastheywerebeforedisassembly.
• Incasecablesaresecuredwithcableties,securingbands,clips,ortapes,removethemrst.
Besuretosecurethecablesinplaceinthesamemannerastheywerebeforedisassembly.
 Before Starting Repair or Servicing
• RemovetheACadaptor,ACcordorbatteries.
• Remove accessories such as the music stand.
 Flowchart
B. PCB UNIT/MAIN
C. PCB UNIT/POWER & AMP
A. Panel Unit
Assembled Product
D. SPEAKER
E. KEY
F. PCB UNIT/KYA
G. PCB UNIT/LDA
PCB UNIT/LD3
PCB UNIT/LD4
PCB UNIT/LD5

LK-127
– 8 –
 Disassembly Procedure
A. Remove the Panel Unit
A-1. Undo 11 screws on the bottom surface of the main unit
A-2. When replacing the keyboard LED PCB, undo 16 screws and then remove the LOWER COVER.
LOWER COVER/C LOWER COVER/B LOWER COVER/A
<Notes on Assembly>
• To install the LOWER COVER, tighten the screws indicated with arrows engraved on each
cover rst.
LOWER COVER/C LOWER COVER/B LOWER COVER/A