Casio Privia PX-720 Troubleshooting guide

ELECTRONIC KEYBOARD
(without price)
PX-720/PX-720C
SEP. 2007
Ver. 6 : Oct. 2015
PX-720C
INDEX

CONTENTS
SPECIFICATIONS ------------------------------------------------------------------------------------------ 1
BLOCK AND WIRING DIAGRAM --------------------------------------------------------------------- 2
PCB LAYOUT ----------------------------------------------------------------------------------------------- 3
CIRCUIT DESCRIPTION --------------------------------------------------------------------------------- 4
PRINTED CIRCUIT BOARDS -------------------------------------------------------------------------- 5
DISASSEMBLY --------------------------------------------------------------------------------------------- 7
DIAGNOSTIC PROGRAM ------------------------------------------------------------------------------18
EXPLODED VIEW ----------------------------------------------------------------------------------------21
PARTS LIST ------------------------------------------------------------------------------------------------23
SCHEMATIC DIAGRAMS -------------------------------------------------------------------------------27

– 1 –
SPECIFICATIONS
Keyboard: 88-key piano keyboard, with Touch Response
Maximum Polyphony: 128 notes
Tones: 11
• Layer (excluding bass tones)
• Split (Low-range bass tones only)
Effects: Brilliance (−3 to +3), Reverb (4 types), chorus (4 types), Acoustic Resonance
Metronome:
• Beats: 0, 2, 3, 4, 6
• Tempo Range: 20 to 255
Duet: Adjustable tone range (−1 to +2 octaves)
Music Library:
• Number of Songs: 60
• Song volume: Adjustable
• Part On/Off: L, R
Recorder:
• Functions: Real-time recording, playback
• Number of Song: 1
• Number of Tracks: 2
• Capacity: Approximately 5,000 notes total
• Recorded Data Protection: Built-in flash memory
Pedals: Damper, soft, sostenuto
Other Functions:
• Touch Select: 3 types, Off
• Transpose: 2 octaves (−12 to 0 to 12)
• Tuning: A4 = 440.0 Hz ±99 cents (variable)
• Operation Lock
MIDI: 16-channel multi-timbre receive
Inputs/Outputs:
• PHONES jack: Stereo standard jacks × 2
Output impedance: 170Ω
Output Voltage: 5.6V (RMS) MAX
• Power: 12V DC
• MIDI OUT/IN terminals
• Pedal connector
Speakers:
φ
12cm × 2 (Output 8W + 8W)
Power Requirements: AC Adaptor: AD-12
Power Consumption: 12V 18W
Dimensions: Digital Piano and Stand: 137.1 (W) × 29.8 (D) × 79.2 (H) cm (54 × 11 3/4 × 31 3/16 inch)
Weight: Digital Piano and Stand: approximately 32.0 kg (70.5 lbs)

– 2 –
BLOCK AND WIRING DIAGRAM
RAM (64Mbit)
IC2
Reset IC
IC1
RESET
12MHz
SAD0 ~ SAD12,
SDBA0,SDBA1
SDD0 ~ SDD15
D8 ~ MD15
Power Amplifier
IC201
Filter
IC205
FLASH (128Mbit)
IC6
ROM (16Mbit)
IC7
A1 ~ A20
D0 ~ D15
MA0 ~ MA3
MD0 ~ MD15
KEY CONTROLLER
IC11
Keyboard
Power Supply Circuit
IC202,Q206,Q207
(12V)
VA12
(5V)
VD5
(5V)
VE5
(12V)
VC
Speakers
(L) (R)
Main
Volume
CONSOLE PCB
(M681-CNA1)
CONSOLE PCB
(M406-CNA4)
Keyboard PCBs
(MCPZ-KYA1/KYB2/KYA3)
SUB PCB
(M408-PSA1)
CONSOLE PCB (M681-CNA3)
CONSOLE PCB
(M681-CNA2)
MAIN PCB (M408-MDA1)
Buttons
SI0 ~ SI10 FI0 ~ FI10
LOUT ROUT
KC0 ~ KC7
MPU
IC5
Control signal
Power
Switch
DAC
IC10
CN9CN13CN2
CN601CN211
CN605
CN14
CN602
CN206
CN203
CN207
CN603
CN15
CN604
CN607
CN606 CN201
CN209
CN204

– 3 –
PCB LAYOUT
PCB Components
MAIN PCB M408-MDA1 MPU, Reset IC, RAM(64Mbit), FLASH memory(128Mbit),
ROM(16Mbit), DAC, Key controller
SUB PCB M408-PSA1 Power supply circuit, Filter, Power amplifer
Console PCBs M681-CNA1 Button, Main volume
M681-CNA2 Phones jack
M681-CNA3 DC 12V terminal, MIDI OUT/IN terminals
M681-CNA4 Power lamp
Rear
M408-MDA1 PCB
M681-CNA1 PCB
M68
1-
C
NA4 P
CB
M681-CNA2 PCB
M681-CNA3 PCB
M408-PSA1 PCB

– 4 –
CIRCUIT DESCRIPTION
KEY MATRIX
NOMENCLATURE OF KEYS
KC0 KC1 KC2 KC3 KC4 KC5 KC6 KC7
FI0 A0A0#B0C1C1#D1D1#E1
SI0 A0A0#B0C1C1#D1D1#E1
FI1 F1F1#G1G1#A1A1#B1C2
SI1 F1F1#G1G1#A1A1#B1C2
FI2 C2#D2D2#E2F2F2#G2G2#
SI2 C2#D2D2#E2F2F2#G2G2#
FI3 A2A2#B2C3C3#D3D3#E3
SI3 A2A2#B2C3C3#D3D3#E3
FI4 F3F3#G3G3#A3A3#B3C4
SI4 F3F3#G3G3#A3A3#B3C4
FI5 C4#D4D4#E4F4F4#G4G4#
SI5 C4#D4D4#E4F4F4#G4G4#
FI6 A4A4#B4C5C5#D5D5#E5
SI6 A4A4#B4C5C5#D5D5#E5
FI7 F5F5#G5G5#A5A5#B5C6
SI7 F5F5#G5G5#A5A5#B5C6
FI8 C6#D6D6#E6F6F6#G6G6#
SI8 C6#D6D6#E6F6F6#G6G6#
FI9 A6A6#B6C7C7#D7D7#E7
SI9 A6A6#B6C7C7#D7D7#E7
FI10 F7F7#G7G7#A7A7#B7C8
SI10 F7F7#G7G7#A7A7#B7C8
F#3G#3 A#3 C#4D#4 F#4G#4A#4 C#5D#5 F#5G#5 A#5
F3 G3 A3 B3 C4 D4 E4 F4 G4 A4 B4 C5 D5 E5 F5 G5 A5 B5 C6
D#3
C2 D2 E2 F2 G2 A2 B2 C3 D3 E3 B6A6G6F6E6D6 C7
C#3A#2G#2F#2D#2C#2
C1 D1 E1 F1 G1 A1 B1A0 B0
A#1A#0 G#1F#1D#1C#1 A#6G#6F#6D#6C#6
B7A7G7F7E7D7 C8
A#7G#7F#7D#7C#7
BUTTON MATRIX
SWB SWC SWD SWE
SI0
SONG
/
MODERN METRONOME
SI1 L / R RECORDER CLASSIC
TONE/
SETTING

– 5 –
PRINTED CIRCUIT BOARDS
Main PCB M408-MDA1
Sub PCB M408-PSA1

– 6 –
Console PCB M681-CNA1 Console PCB M681-CNA2
Console PCB M681-CNA3 Console PCB M681-CNA4

– 7 –
DISASSEMBLY
■ To remove main body and speaker box.
*The screws come with the cap.
*Do not forget to attach the screw caps when assembling.
1. Remove the Connector and Pedal cord.
2. Remove 2 screws and then the Pedal unit
3. To damage neither the floor nor the main body, the main body is put on the mat or the blanket, etc.
4. Remove 8 screws and take off the left and right outer side covers.
ConnectorPedal cord Screws
Pedal unit
Main body
Speaker box

– 8 –
■ Speaker box disassembly
1. Remove the 20 screws and then the back of the speaker box.
2. Remove the 4 screws for each speaker and then take out the speakers (left and right).
■ Removing the T-BRD-UNIT.
1. Remove 18 screws and then the T-BRD unit.
T-BRD unit

– 9 –
■ Removing the Key cover.
1. Remove the 4 screws and the 2 stoppers on the left and right ends.
Precautions During Assembly
To avoid any risk of damaging the stoppers during installation, do not use an electric screwdriver.
2. Remove the key cover.
Stoppers
Key cover

– 10 –
■ Removing the PCBs (M408-MDA1 PCB, M408-PSA1 PCB, M681-CNA3 PCB).
1. Remove the twist ties that hold the cables in place.
3. Remove the PCB case.
M408-MDA1 PCB M408-PSA1 PCB M681-CNA3 PCB
2. Remove 8 screws

– 11 –
4. Remove the 11 connectors, release the lock and then remove the FPC.
Connector
(M681-CNA1)
Connector
(M681-CNA1)
Connector
(M681-CNA3)
Connector
(SPEAKER(R))
Connector
(M681-CNA4)
Connector
(Pedal)
FPC
(Keyboard)
Connector
(M408-MDA1)
Connector
(M681-CNA3)
Connector
(M681-CNA2)
Connector
(SPEAKER(L))
Connector
(Power SW)
5. Remove 4 screws and the M408-MDA1 PCB.
6. Remove 6 screws and the M408-PSA1 PCB.
7. Remove 3 screws and the M681-CNA3 PCB.
M408-MDA1 PCB M408-PSA1 PCB M681-CNA3 PCB

– 12 –
■ Removing the Pedal connector.
1. Remove 2 screws and then the Pedal connector.
■ Removing the Front board.
1. Remove the 10 screws and lift up the front board.
* The panel is still connected by a lead.
2. Remove the front board.
Front board
■ Removing the M681-CN4 PCB.
1. Remove 2 screws and the M681-CNA4 PCB.
M681-CNA4 PCB

– 13 –
■ To remove the CN-PANEL
2. Remove 4 screws and the CN-PANEL.
CN-PANEL
■ Removing the Side block
1. Remove the 6 screws.(left and right).
<The left side> <The right side>
2. Remove the side units (left and right).

– 14 –
■ Disassembling the left side unit (M681-CNA1 PCB, M681-CNA2PCB)
1. Remove the side case.
4. Remove 4 screws.
5. Remove the volume knob and the rubber key and M681-CNA1 PCB.
2. Remove 2 screws and the M681-CNA2 unit.
3. Remove 2 nuts and the M681-CNA2 PCB.
M681-CNA2 PCB
M681-CNA1 PCB
Rubber key

– 15 –
■ Disassembling the right side unit (Power switch)
1. Remove the side case.
2. Remove 2 screws and the Power switch.
Power switch

– 16 –
2. Remove 24 screws and then the KEY-BOARD ASSY.
3. Remove the keys.
■ To remove the Keyboard
1. Remove 2 screws and then 2 brackets

– 17 –
Caution while assembling the keys.
• Set the key as shown in figures below.
4. Remove 8 rubber keys.
* One of the keys has the different length from others.
5. Remove 9 screws then the MCPZ-KYA1 PCB.
6. Remove 11 screws then the MCPZ-KYB2 PCB.
7. Remove 9 screws then the MCPZ-KYA3 PCB.
How to install the rubber keys.
MCPZ-KYA1 PCB
*SCREW x 9
MCPZ-KYB2 PCB
*SCREW x 11
MCPZ-KYA3 PCB
*SCREW x 9

– 18 –
DIAGNOSTIC PROGRAM
 Initial Setting
1. Connect the AC adaptor.
2. Connect the pedal.
NOTE: If there is no pedal, pedal check can be skipped.
3. “Main” volume: MAX
 How to start diagnostic program
1. While pressing down “METRONOME”, “RECORDER”, and “/” buttons at the same time, turn the power ON.
* Wait for confirmation chords C4, E4, G4 sound.
2. Release “METRONOME”, “RECORDER”, and “/” buttons
 Diagnostic program
1. Automatic Test
 RAM check
 ROM check
“L / R” or “/” lights when an error is found in ROM.
 LED check
The LEDs light in thesequence shown below
2. MODEL check
 Press “TONE/SETTING” button to perform the “MODEL check.”
The confirmation chords C4, E4, G4 sounds.
“R” LED flashes.