Service Manual CASIO CTK-541 ELECTRONIC KEYBOARD

ELECTRONIC KEYBOARD CTK-541 JULY.1999 CTK-541 E E E

CONTENTS Specifications ................................................................................................................................... 1 Block Diagram .................................................................................................................................. 3 Circuit Description ............................................................................................................................ 4 Adjustment ....................................................................................................................................... 8 Major Waveforms ........................................................................................................................... 10 Printed Circuit Boards .................................................................................................................... 11 Schematic Diagrams ...................................................................................................................... 15 Exploded View ............................................................................................................................... 19 Parts List ........................................................................................................................................ 20

— 1 — SPECIFICATIONS GENERAL Keyboard: 61 standard-size keys, 5 octaves (with touch response on/off) Tones: 100 Polyphony: 16 notes maximum (8 for certain tones) Auto accompaniment Rhythm patterns: 100 Tempo: Variable (236 steps, = 20 to 255) Chords: 2 fingering methods (CASIO CHORD, FINGERED) Rhythm controller: START/STOP, SYNCHRO/FILL-IN Accomp volume: 0 to 9 (10 steps) Song bank Tunes: 100 Controllers: PLAY/PAUSE, STOP, REW, FF, LEFT ON/OFF (ACCOMP), RIGHT ON/ OFF (MELODY) Display Name display: TONE, RHYTHM, SONG BANK name/number, keyboard settings name/value Tempo: Tempo value, metronome, synchro standby, beat indicator Chord: Chord name, Chord form Fingering: Fingering indicators, parts, pedal Song bank status: PLAY, PAUSE, REW, FF Staff: 5 octaves with sharp and flat indications Keyboard: 5 octaves MIDI: 5 multi-timbre receive Other functions Transpose: 12 steps (–6 semitones to +5 semitones) Tuning: Variable (A4 = approximately 440 Hz ± 50 cents) Volume: 0 to 9 (10 steps) Terminals MIDI terminals: IN, OUT Sustain terminal: Standard jack Phones/Output terminal: Stereo standard jack Output Impedance: 50 Ω Output Voltage: 3.5 V (RMS) MAX Power supply terminal: 9 V DC Power supply DC 9 V Batteries: 6 D-size batteries Battery life: Approximately 5 hours on manganese batteries Auto power off: Turns power off approximately six minutes after last key operation. Enabled under battery power only, can be disabled manually. Speaker output: 2.0 W + 2.0 W Power consumption: 9 V --- 7.7 W Dimensions (HWD): 961 × 376 × 143 mm (37-7/8 × 14-13/16 × 5-5/8 inches) Weight: Approximately 5.7 kg (12.6 lbs) (without batteries)

— 2 — ELECTRICAL Current drain with 9 V DC: Nominal Limit No sound output 330 mA 330 mA ± 20% Maximum volume 990 mA 990 mA ± 20% with 16 keys C1 to D3 pressed in Synth-Lead 1 Volume: Maximum, Touch response: ON(Velocity MAX) Phone output level (Vrms with 8 Ω load each channel): L 240mV 240 mV ± 20% with key C3 pressed in Synth-Lead 1 R 250mV 250 mV ± 20% Speaker output level (Vrms with 4 Ω load each channel): with key G1 pressed in Synth-Lead 1 L/R 2500mV 2500 mV ± 20% Output level (Vrms with 47 KΩ load each channel): L 2300mV 2300 mV ± 20% with key C2 pressed in Synth-Lead 1 R 2400mV 2400 mV ± 20% Minimum operating voltage: 6.3V 7.0V

— 3 — BLOCK DIAGRAM CPU GT913F(T) LSI1 Keyboard Buttons LCD LCD Driver KS0066U-10B LSI3 Reset IC UPD6379GR-E1 IC1 Oscillator X1, Q1 Power Supply Circuit Q201 ~ Q203, Q207, Q208, D205 Power Amp. TA8248K IC201 Filter (L) Q206 Filter (R) Q205 Phone/Output VC VCC DVDD AVDD APO DC + 9V IN DB4 ~ DB7 MIDI IN MIDI OUT COM1 ~ COM16 SEG1 ~ SEG40 RS R/W E KI0,KI1 FI8~FI10 FI0 ~ FI7 KC0 ~ KC7 MD0 ~ MD15 MA0 ~ MA19 ROM(8M-bit) MSM538002E- N8GS - KDR1 LSI2 Power Switch

— 4 — CIRCUIT DESCRIPTION KEY MATRIX NOMENCLATURE OF KEYS KI0 KI1 KI2 KI3 KI4 KI5 KI6 KI7 KO0 C2 G#2 E3 C4 G#4 E5 C6 G#6 KO1 C#2 A2 F3 C#4 A4 F5 C#6 A6 KO2 D2 A#2 F#3 D4 A#4 F#5 D6 A#6 KO3 D#2 B2 G3 D#4 B4 G5 D#6 B6 KO4 E2 C3 G#3 E4 C5 G#5 E6 C7 KO5 F2 C#3 A3 F4 C#5 A5 F6 KO6 F#2 D3 A#3 F#4 D5 A#5 F#6 KO7 G2 D#3 B3 G4 D#5 B5 G6 KO8 — + 0 KO9 3 2 1 KO10 6 5 4 Rhythm Tone KO11 9 8 7 Fingered Normal Off KO12 FF Right Stop Left REW Tempo Down Tempo Up Start/ Stop Synchro/ Fill-In Chord Book Accomp Volume Transpose/ Tune/MIDI Song Bank CASIO Chord Play/ Pause Volume Down Volume Up F#3 G#3 A#3 C#4 D#4 F#4 G#4 A#4 C#5 D#5 F#5 G#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 B6 A6 G6 F6 E6 D6 C7 C#3 A#2 G#2 F#2 D#2 C#2 A#6 G#6 F#6 D#6 C#6

— 5 — CPU (LSI1: GT-913F) The 16-bit CPU contains a 1k-byte RAM, three 8-bit I/O ports, two timers, a key controller and serial interfaces. The CPU detects key velocity by counting the time between first-key input signal FI and second-key SI from the keyboard. The CPU reads sound data and velocity data from the sound source ROM in accordance with the selected tone; the CPU can read rhythm data simultaneously when a rhythm pattern is selected. Then the CPU provides 16-bit serial sound data to the DSP. The CPU also controls MIDI input/output and stores sequencer data into the working storage RAM. The following table shows the pin functions of LSI1. Pin No. Terminal In/Out Function 1 TXD0 Out MIDI signal output 2 RXD0 In MIDI signal input 3 SCK0 Out APO (Auto Power Off) signal output 4, 5 TXD/P13, In/Out Data bus for the LCD driver RXD/P14 6 SCK1 Out 1 MHZ synchronizing pulse output 7 AVCC In CVDD (+5 V) source AC adaptor detection terminal. 8 AN0 In +5 V when the keyboard is powered by batteries and becomes 0 V to cancel the APO function when AC adaptor is connected. 9 AN1 In Input from pitch bender 10 AGND In Ground (0 V) source 11 BCK Out Bit clock output 12 SO Out Serial sound data output 13 LRCK Out Word clock output 14 GND In Ground (0 V) source 15, 16 XLT0, XLT1 In/Out 30 MHz clock input/output 17 VCC In +5 V source 18, 19 MOD0, MOD1 In Mode selection terminal 20 RSTB In Reset signal input 21 NMI In Power ON signal input 22 INT/P10 In/Out Data bus for the LCD driver 23 ~ 30 FI0 ~ FI3 In Terminal for key input signal SI0 ~ SI3 31 ~ 38 KC0 ~ KC7 Out Terminal for key scan signal 39 ~ 50 FI4 ~ FI9 In Terminal for key input signal SI4 ~ SI9 51 FI10 In Terminal for button input signal 52 SI10/P23 Out Chip enable signal for the LCD driver 53 ~ 55 KI0 ~ KI2 In Terminal for button input signal 56 MWNB Out Write enable signal for the DSP 57 ~ 76 MA0 ~ MA19 Out Address bus 77 MCSB0 Out Chip enable signal output for the sound source ROM 78 MCSB1 Out Not used 79 MCSB2 Out Chip enable signal output for the DSP

— 6 — Pin No. Terminal In/Out Function 80 VCC In +5 V source 81 GND In Ground (0 V) source 82 MRDB Out Read enable signal output for the sound source ROM 83 ~ 98 MD0 ~ MD15 In/Out Data bus 99 PLE Out Reset signal output for the DSP 100 P17 In/Out Data bus for the LCD driver LCD DRIVER (LSI3: KS0066U-10B) The LCD driver can drive a dot matrix LCD having 40 segment and 16 common lines. The LSI contains 240 graphic symbols in the built-in character generator ROM, and stores 80 characters in the built-in display data RAM. In accordance with command from the CPU, the LSI is capable of displaying up to 16 characters simultaneously. The following table shows the pin functions of KS0066U-10B. Pin No. Terminal In/Out Function 1 ~ 22, 63 ~ 80 23 VSS — GND (0 V) source Terminals for the built-in clock pulse generator. The external resistor connected determines the oscillation frequency. LCD drive voltage input. 26 ~ 30 V1 ~ V5 In Those voltages are used for generating the stepped pulse of the LCD drive signals. 31, 32 LP, XCLS — Not used 33 VDD In DVDD (+5 V) source 34, 35 FR, DO — Not used Data/command determination terminal. High: data, Low: command 37 R/W In Read/Write terminal. High: read, Low: write Chip enable signal. 38 E In High: enable, the writing is done at fall edge. Low: disenable 39 ~ 42 DB0 ~ DB3 — Not used. Connected to GND (0 V) 43 ~ 46 DB4 ~ DB7 In/Out Data bus 47 ~ 62 COM1 ~ COM16 Out Common signal/output SEG1 ~ SEG40 Out Segment signal output 24, 25 OSC1, OSC2 In/Out 36 RS In

— 7 — FILTER BLOCK Since the sound signals from the CPU is stepped waveforms, the filter block is added to smooth the waveforms. POWER AMPLIFIER (IC201: TA8248K) The power amplifier is a two-channel amplifier with standby switch. The following table shows the pin function of IC201. Pin No. Terminal In/Out Function 1 NC — Not used 2 B.S.2 — Terminal for a bootstrap capacitor 3 OUT2 Out Channel 2 output 4 VCC In +9 V source 5 OUT1 Out Channel 1 output 6 B.S.1 — Terminal for a bootstrap capacitor 7 Power GND In Ground (0 V) source 8 Stand by In Power control signal input. 0 V: Off, +9 V: On 9 DC — Terminal for a decoupling capacitor 10 NF1 In Negative feedback input 11 IN1 In Channel 1 input 12 IN2 In Channel 2 input 13 NF2 In Negative feedback input 14, 15 Pre GND In Ground (0 V) source Amp. TA8248K Filter Block CPU MSM6755B-17

— 8 — ADJUSTMENT MAIN PCB 1) Items to be adjusted: 2) Adjustment and Test Point Locations Item Measuring Instrument Vop voltage setting Voltmeter VR1 (BOTTOM VIEW) Test point (TOP VIEW)

Service Manual CASIO CTK-541 ELECTRONIC KEYBOARD

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