Onkyo TA-2058 User Manual

TA2058
3. DA Converter and Data Setting Method
The D/A converter circuitry is outlined in Figure 5, and the
logic diagram of the 4024BP 7-stage binary counter in
Figure 6. The 4024BP counter is counted up each time a
negative input pulse is applied to the clock pin, the out-
put data being obtained from Q1 thru Q7 (although only
Q1 thru QS are actually used). This output is converted to
an analog quantity when passed through the R—2R rudder
resistance circuit.
If the power supply voltage is 5V, the voltage per step is
approximately 0.156V with a total of about 4.84V. Since
this 4024BP is only involved in up counting, setting to a
value lower than the current value (that is, greater bias)
results in an initial clearing and output of pulses until the
set value is reached.
clock Ui}
LM6402H-425
4024BP
Fig. 5 DA converter circuitry
Qi Q2 Q3 Q4 Qs a6
(12) a) (9) (6) (5) (4)
Lo oo a i a a
A A A A A
Ls oH | Usa
A
ey. =
po
CLEAR (2)
DB 6
CP
a R a
Fig.6 4024BP logic circuit
4, Input Port Expander IC
The equivalent circuit of the LC7800 used to expand input
ports is shown in Figure 7. This IC includes four 4-bit input
ports, one 4-bit output port, and one 4-bit selector input
port. When BA of the selector input is set to LOW and the
other bits to HIGH, the AO” Al” A2” A3 input port is con-
nected to the DO” D1” D2” D3 output port. And if only
the BB bit is set to LOW, the BO” B1” B2” B3 input is se-
lected. Hence, a LOW level signal is applied to the selector
port bits in cyclic order, and the operation indicator LEDs
are switched on and off dynamically in combination with
the #13, #14, and #15 LED output ports while input port
data is being read out.
sd!
°
pO ar OFA arr oO wi
Co =_ — _ o ao
Ql OO); wir)
i Le iw a
Oo Sn D-
—_ | —
)_.
ra
iad
' .
: all — © 4
py | SS Ee =) pe
atl fs
adi ||
ALPE EPO 25
Ara] to I).
Aa | ef
S0he-
Wty
ESL
508
ff | Poe Sopy =
aL | foo 7
iene.
-s TT a) —
ae SL 25:
4 Pe —d) x.
Fim =— ab
=p
e O CO OO)
INENLZALS
CP—0< 0 INH
NAAL —_
ry Oo Oo * O INH
194 205 215 422 276 0 hts 28
Sa Sa Sc So Yoo Vss
Fig. 7 LC7800 equivalent circuit
i sL Ls sh LG ,
cP cP CP cP
Z a a a a a
Anaiog output

Onkyo TA-2058 Specifications

General

Brand	Onkyo
Model	TA-2058
Category	Cassette Player
Language	English