CASIO CTK330
Service Manual

CPU (LSI101: MSM6755B-06)
The CPU contains a sound data ROM and a DAC (Digital to Analog Convertor), and it provides left and right channel sound waveforms in accordance with the pressed key and the selected tone. The following table shows the pin functions of LSI101.
Pin No. 1 ~ 29 30 31 32, 33 34 35 36 37 38 39 40 41 42, 43 44 45 46 47 48 49 50 51 52 53 54 55, 56 57 58 ~ 65 66 ~ 73 74 ~ 77 78 79 80 ~ 82 83 ~ 87 88 ~ 95 96 97 ~ 100 Terminal MA14 ~ NC2 DGND DVCC XTLO, XTLI NC3 RSTB P24/RXD P25/TXD NMI APO NC4 REFH NC5, NC6 DAOR NC7 AVdac DAOL REFL AGdac AGadc ANI AVadc NC8 MOD0 MOD1, MOD2 KO9/P40 KI0/P30 ~ KI7/P37 KO1/P50 ~ KO8/P57 P20 ~ P23 NC9 LVCC CC1 ~ CC3 � La ~ Lg, Lp LGND � In/Out � In In In/Out � In � � In Out � Out � Out � In Out Out In In � In � In In In In Out Out � In Out � Out In � Function Not used. Ground (0 V) source +5 V source 20 MHz clock input/output Not used. Connected to ground. Reset signal input Not used. Connected to +5 V. Not used. Power on signal input. Connected to +5 V. APO (Auto Power Off) signal output Not used. Terminal for the built-in DAC Not used. Right channel sound waveform output Not used. +5 V source for the built-in DAC and ADC Left channel sound waveform output Terminal for the built-in DAC and ADC Ground source for the built-in DAC Ground source for the built-in ADC Not used. Connected to ground. +5 V source for the internal ADC Not used. Connected to +5 V. Mode selection terminal Mode selection terminal APO cancelation signal input Terminals for key/button input signal Terminals for key scan signal Terminals for button scan signal Not used. +5 V source LED common signal output Not used. LED segment signal output Ground (0 V) source Not used.

FILTER BLOCK
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.

Amp. LA4598

Filter Block

CPU MSM6755B-08

MC-Service
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