Table of Contents
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A.Command input with operating keys (buttons)
The stored control program causes the controller
. to keep watch of the states of the operating keys
and other input signals (commands). If you de-
press the REC key, for example, port I2 of U912
turns to H-level. On the other hand, the controller
Outputs a 3-bit address code through its output
ports (CO—C2)
to the input ports (SO—S2) of
_ multiplexer IC U912. U912 outputs L-level at
output port Z when [2 is at H and SO—S2 are
respectively at H, L, and L (see Table 3-4). The
L-level at Z is inverted by transistor Q901 and
applied to port A3 of the controller. When H is
applied to A3, the controller identifies the REC
as depressed. Next, the controller applies signals
L, L, and H to SO—S2 to see whether or not the
PLAY button is depressed. If PLAY is depressed
at this time, the multiplexer. is at H-level at 14
and, as a result of AND with the signals of SO—
$2, outputs L-level. This.permits.the.controller
-....
to identify the PLAY button as depressed. (If
the PLAY button is not depressed, the output
level at'Z 'is H and the input'to the controller is
L. Asa
result, the controller identifies the PLAY
button-as-not depressed.-Naturally; no control
signals used for recording operation are generat-
ed.)
In the same
way,
the controller checks
whether or not port 17 of multiplexer IC U9 12 is
at H-level
(i.e. whether or not the tab of the
cassette is removed; and REC mode is set for at
least one of the three channels.) Thus the con-
trol program: forees-the--controller -to--check-all
requirements for performing recording and gen-
erate signals needed for recording operation if
the requirements are met.
CONTROLLER
U9I3
ugoll
Fig. 3-14
In the other operating
modes,
the controller
actually operates in the same way to check com-
mand and generates needed control signa's. .
Figure 3-8 shows the timing of control signals in
relation to operating commands.
A specific se-
quence of control signals totally control the tape
drive mechanism and amplifier.
B.Command
input
with
operating
switches
(Auto-Present)
In this case, too, the way of inputting commands
and how the controller checks commands
are
the same as when using the operating keys. More
detail will be given fater.
"3-8. SOLENOID
DRIVE CIRCUIT
3-8-1. Fast solenoid drive circuit
See Fig. 3-14.
As
described
before,
the controller
outputs
a
Tlashing.pulse.at-pin-10-(see Fig..3-8) aad-+Hevel
at pin 13 (at pin 5 during REW) during a Fast
"mode.(F.FWD.or REW).
During F.FWD
the Fast solenoid
operates as
follows.
a. Controtter U913 outputs H-fevel at pin 13.
b. The H-level applies to the base of transistor
"Q911
via.resistor U901C,
thereby. turning_it
on. Now the Fast solenoid is grounded at an
end,
:
c. On
the other hand, U913
outputs
flashing
pulse whose width is 220 msec at pin 10.
d. The flashing pulse-applies to the base of tran-
sistor Q906, thereby turning it on. As 0906 is
on, its base current turns of 0907.
Now the
high level developing at Q907's emitter applies
+13V
] FAST
SOL.
Fast solenoid drive circuit
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