1
2
3
4
5
6
7
8
9
10
11
12
Pin No.
Symbol Description
Power VCC
Power out
Power GND
Power NF
Power in
SP mute control
Preamp.
mute control
MIC/LIN
control
REC/PLAY
control
VOX out
VOX DET
VREF
■ Pin Descriptions
13
14
15
16
17
18
19
20
EQ–amp. out
EQ–amp. NF
Head in/out
REC ADJ
VOX in
Pre out
Pre NF
ALC DET
Loudspeaker amplifier power supply input
An external power supply connects to this pin. The input supply voltage range is 4.5 to 9V.
Loudspeaker amplifier output
This pin connects through an electrolytic capacitor to a loudspeaker with a load impedance of 8Ω or
more. This pin is effective only when Pin6 is high.
Loudspeaker amplifier ground
This pin connects to an external ground. This ground should be separated from that of the preampli-
fier circuits.
Loudspeaker amplifier inverse input
A combination of resistors and a capacitor connected between this pin and Pin2 and the ground
determines the gain and frequency characteristics of the loudspeaker amplifier.
Loudspeaker amplifier non-inverse input
Signals should be input to this pin through a capacitor. The expected input impedance is typically 27kΩ.
Loudspeaker amplifier mute control
If the voltage level at this pin is high, the loudspeaker amplifier turns ON, and if low, turns OFF.
Preamplifier mute control
If the voltage level at this pin is high, the preamplifier turns OFF, thereby blocking the MIC and
line preamplifier outputs. If the voltage is low, the preamplifier turns ON. Even if the preamplifier
is turned OFF (mute ON), signals input to Pin9 are output from Pin18.
MIC/line preamplifier switching
If the input to Pin7 is low and the input to this pin is high, then the line preamplifier turns ON and
the MIC preamplifier turns OFF. If the input to Pin7 is low and the input to this pin is low, then the
line preamplifier turns OFF and the MIC preamplifier turns ON.
REC/PLAY switching
If the input to this pin is high, the recording amplifier turns OFF, and the play equalizer amplifier
turns ON. If low, the recording amplifier turns ON, and the play equalizer amplifier turns OFF.
VOX output
The VOX detection signal is output from this pin. This pin should be connected through a resistor
(100-200kΩ) to the power supply.
VOX detection control
This pin should be connected through a resistor (10 to 470kΩ) and a capacitor in parallel to the
ground. The resistance determines the sensitivity of VOX detection.
Internal reference supply voltage output
This pin should be grounded through a 100µF capacitor.
Equalizer amplifier output
Amplified play signals from the head are output from this pin. A resistor and capacitors connected
between this pin and Pin14 determine the equalizer characteristics.
Equalizer amplifier inverse input
This pin connects through a resistor to Pin13 to determine the equalizer characteristics. The expect-
ed input impedance is typically 10kΩ.
To the REC/PLAY head
A REC/PLAY head must be connected between this pin and the ground. Switching of REC and
PLAY modes is done by Pin9. A load resistor should be connected between this pin and the ground
because the input impedance becomes high (several hundred kilohms) in the PLAY mode.
REC gain control
A resistance connected between this pin and the ground determines the head bias current in the REC
mode. The lower the resistance, the higher the current. A serial combination of a resistance and a
capacitance, connected in parallel with the resistance, determines the REC gain.
VOX amplifier input
The preamplifier output at Pin18 must be connected through a resistor and a capacitor to this pin.
The impedance between Pin18 and this pin determines the gain, and a resistance betweeen Pin11
and the ground determines the frequency characteristics of the VOX amplifier.
Preamplifier output
Amplified MIC/line preamplifier outputs are output from this pin depending on the the statuses of
Pin7 (preamplifier mute) and Pin8 (MIC/line switching).
Preamplifier inverse input
Resistors and a capacitor connected between this pin and Pin18 and 12 determine the preamplifier
gain. The input impedance at this pin is several hundred kilohms.
ALC detection control
A 240kΩ resistor and a 4.7µF capacitor connected in parallel between this pin and the ground control ALC detection sensitivity.