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Pin No.
28
29, 30
31 ~ 38, 40 ~ 43
44
FILTER BLOCK
Since the sound signals from the DAC are stepped waveforms, the filter block is added to smooth the
waveforms.
Main
Volume
To Power Amp.
POWER AMPLIFIER (IC202: LA4598)
The power amplifier is a two-channel amplifier with standby switch.
The following table shows the pin function of IC202.
Pin No.
Terminal
1
Power GND
2
Ch1 B.S.
3
Ch1 OUT
4
VCC
5
Ch1 N.F.
6
Ch1 IN
7
D.C.
8
Pre GND
9
Stand by
10
Ch2 IN
11
Ch2 N.F.
12
Ch2 OUT
13
Ch2 B.S.
14
NC
Terminal
I n / O u t
SAMPB
Out
D0, D1
In
A4 ~ A15
In
K0O
In
AVDD
22 Ω R236
Q207
2SC1740SR
AG
AG
Q208
2SC1740SR
C243
AG
AG
In/Out
In
Ground (0 V) source
—
Terminal for a bootstrap capacitor
Out
Channel 1 output
In
+9 V source
In
Negative feedback input
In
Channel 1 input
—
Terminal for a decoupling capacitor
In
Ground (0 V) source
In
Power control signal input. 0 V: Off, +9 V: On
In
Channel 2 input
In
Negative feedback input
Out
Channel 2 output
—
Terminal for a bootstrap capacitor
—
Not used
— 13 —
Working Storage RAM chip select signal
Data bus
Address bus
Clock pulse from CPU
R247
R245
R243
1K
1K
1K
C242
C223(H)
AG
R248
R246
R244
1K
1K
1K
C223[H]
AG
Function
Function
From DA Converter
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