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5. CIRCUIT DESCRIPTIONS
The main circuit configuration is outlined in the
block diagram on page 15.
5.1 SIGNAL PATH
Recording Mode
The input signal from LINE INPUT is passed via
the INPUT volume control, flat amplifier and MpX
filter before being applied to the Dolby NR circuit.
The Doly NR circuit output is then applied to
the recording amplifier equalizer where the fre-
quency response is regulated according to the type
of tape being used before finally being applied
to the recording head.
Playback Mode
The playback head output signal is applied to
the playback equalizer (gain 5B.2dB) where the
frequency response is corrected according to the
type of tape being used. Following this, the signal
is passed via the MPX filter to the Dolby NR
circuit, and then via the REC/PB switch (HA1200b
elechonic switch) and MUTE switch (HA12006
electronic switch) to the LINE OUTPUT as the
playback output signal.
5 . 2 C O N T R O L C I R C U I T
The CT-X50 contuol circuit (outlined in Fig. 5-1)
features a logic IC (8A843) for control of mechani-
cal drive by feather-touch switch operations. The
84843 pin layout is shown in Fig. 5-1 and the
input/output::i^:"::
:,t::
t""1
"-
Fû
Sî6F
FF
MÊrio
ru
PA,SE
-REc
cNo
Fig. 5-1 Pin arrangement of 8A843
Power-Assist Mechanism
Before describing circuit operations during each
operational mode, the basic principles of the
power-assist mechanism will be explained.
Gear return spring
Flywheel assembly
Gear lever
Stopper
Fig. S-2 STOp mode
o Stop Mode
1. The cam gear is positioned as shown in Fig. b-2.
o Stop Mode to Play Mode (Figs. b-4, b-b, b-6)
2. When solenoid P (pinch solenoid) is activatede,
the cam gear stopper is released O.
3. The operating lever is then forced down
(direction
@ ) bV the operating lever return
spring, and because of the shape of the cam,
the cam gear starts to turn in direction @.
4. As the cam gear rotates in direction O . it
engages the capstan gear @.
Lever spring
I n p u t s i g n a l
Output
Output mode
U ' T F
O . R E W
O_RE C
O - P A U S E
O - P L A Y
S T O P
L
L
L
L
L
STOP mode
F F
H
H
FF mode
n
L
H
L
L
R E W m o d e
P L A Y
L
L
L
L
H
P L A Y m o d e
P A U S E
L
L
L
L
H
L
P A U S E m o d e
R E C / P L A Y
L
H
L
H
R E C / P L A Y m o d e
B E C / P _ A _ U S E
L
L
H
H
L
REC/PAUSE mode
Fig. 5-3 Input/output truth table
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