Sharp RP-117H - Page 18

RP-107H/117H
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(CIRCUIT AROUND THE MICROCOMPUTER)
POWER CONTROL CIRCUIT
When the power switch is turned on, a power of 5V is caused
to be applied to C203 and R214. About 100 msec after C203
has charged, Q205 turns on and its collector voltage becomes
low level to be sent to pin
24) of the microcomputer, so that
the microcomputer is reset about 100 msec after the power
switch has been turned on.
SIGNALS FROM SENSOR TO MICROCOMPUTER
1.
Turntable chassis open/close detection
Two switches SW204 and SW205 are provided for this
detection.
Opening the turntable chassis causes SW204 to turn on, and
its output signal (at low level) is applied to pin of the
microcomputer: closing the turntable chassis causes SW205
to turn on, and its output signal (at low level) is applied to
pin of the microcomputer.
. Tonearm Rest Position Detection
Photointerrupter P1103 and gear drum are provided for
this detection. Detected by these, the output pulse is
applied to pin 63) of the microcomputer.
. Tonearm position detection
Performed by using the photointerrupter P1103 and gear
drum. Detected by these, the output pulse to show in
which position the tonearm is situated is applied to pin 62)
of the microcomputer.
. Program space detection by APSS sensor
The APSS sensor includes phototransistors PT101 (for side
A) and PT102 (for side B) which differentiate program
space of a record from its usual programs recorded part.
Detected by these transistors, the output signal (at high
level) is applied, after amplified and shaped in waveform, to
pin 44) (for side A) and pin (for side B) of the micro-
computer.
. Audio signal detection
There is caused a signal (at high level) at the beginning or
the end of the program of a record in playing, and after
having been amplified and shaped in waveform, it is applied
to pin of the microcomputer.
CARTRIDGE MOTOR NORMAL/REVERSE ROTATION
SELECTOR CIRCUIT
This circuit consists of 1C104 and changes the power supply to
make the cartridge motor rotate in normal or reverse direction.
® To make the motor rotate in reverse direction (with tone-
arm forward operation):
The motor rotates in reverse direction when pin of the
microcomputer is at low level while its pin is at high
level. See Table 28-1.
To make the motor rotate in normal direction (with tone-
arm backward operation):
The motor rotates in normal direction when pin of the
microcomputer is at low level while its pin is at high
level. See Table 28-1.
When the cartridge forward or reverse key is pushed while
the tonearm is cuing up, there is produced a pulse to drive
the cartridge motor for the first 1130 msec. Thereafter the
motor rotation speed is gradually raised up to its regular
speed. See Fig. 28-2.
MICROCOMPUTER
Resetting Signal
Sv
ov
>
CROCOMPUTER
Pin Resetting
+10V GND
Power _| ‘ome
ae MICROCOMPUTER
N RESET
Figure 28-1
Micro-
computer 1104
Cartridge motor
operation Output Input Output
Pin Pin Pin | Pin Pin Pin Pin
®|i9| ©!|@/©/ @6|a
In reverse rotation
(with tonearm for- H L L H L L H
ward operation) |
In normal rotation
(with tonearm back- L H L L H H L
ward operation) L
In stop (with break
applied) H H Lo H H L L
In tracking (in nor- |
mal direction) c S a L L L ql
Cartridge Motor Normal/Reverse Rotation Selector Circuit
Table 28-1
From
MICROCOMPUTER
(8 Pin
vv
>?
Is:
Icio4
54547P
D109}
$133)
y
From MICROCOMPUTER
9 Pin
O_O) —_ —
QO ~: co) CNSIII
CARTRIDGE MOTOR
CONTROL
Figure 28-2
@)
MIO3
NORMAL ROTATION
ouTPUT
MICROCOMPUTER,
WP
CARTRIDGE MOTOR ROTATION
npiz Cartridge motor
MICROCOMPUTER
19 Pin
Reverse Roranon
N30 mSEC
Output
—28-—
Figure
28-3