Akai GX-747 dbx Service Manual page 19

4-2. SYSTEM CONTROL
The system control circuit using a microcom-
puter will carry out the following controls.
CD
Operational Control of tension arm lock
Q) Indication of real time counter
G) Operation control of function SW
@
Control of reel motor brake system
G)
Flashing control of indication lamps
Since the LED indicator and the electronic
counter indicator are operated by the timing of
pulse, no tester can find the failure.
The failure can only be found by checking the
waveform on the oscilloscope.
(!) ICl (µPD553C-152) Terminal Description
CLOCK
~' " "{
INTERRUPT
RESET
SEGMENT[:
TAPEPULSE
REC OUT
OSC DRIVE
QT RELAY
PB MUTE
REV OUT
PAUSE PLANGER
MOTOR NORMAL
REVOLUTION
REVERSE REVOLUTION
BACK UP
L - - - - - - -
EACH FUNCTION
INPUT
PLAY/FF OUT
Fig. 6-25
@
IC2 (µPD553C-110) Terminal Description
CLOCK
[
3 DIGIT H2
DIGIT INPUT 4 DIGIT H3
5
DIGIT lo
SEGMENT INPUT g
RESET
_,,,,~{
RELAY CTL
0 STOP OUTPUT
TEST
+IOV
PDr
PD2
PEo
PE1
PE2
PE3
PFo
PF1
PF2
PF3
PH1
CLOCK
DIGIT INPUT
2
DIGIT Hr
DIGIT INPUT I DIGIT Ho
REV UP
AUTO STOP
QUE
REEL SIZE
REV H
REW H
REV UP LAMP
AUTO STOP LAMP
REEL MOTOR CTL
Fig. 6-26
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