Voltage Supply - Tatung OMNISCAN SERIES Service Manual

M19 0.7 Vpp
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M20 0.5 Vpp
Pins 31, 32 are CLOCK INPUT and CLOCK OUTPUT,
a clock generating circuit is built into the processor,
so if a resonator X501 (4MHz) is connected to the
clock I/O pins a 4MHz clock signal can be obtained.
Pin 42 is supply voltage pin, it connect to + 5V power
supply.
Pin 21 is ground pin, it connect to OV power supply.
SYSTEM RESET
G+SYNC.
H+V
SEPARATE
H SYNC. +
H SYNC.-
V SYNC. +
V SYNC.-
ID1
LO
HI
HI
ID4
LO
HI
ID2
HI
HI
LO
ID5
LO
HI
LO
LO
Pin 15 is the V POLARITY OETECTION input for
0512. When the polarity of vertical sync. is positive,
this pin is "LOW".
(Refer to circuit diagram Fig-29)
Pin 1.6 is the H POLARITY OETECTION input for
0512.
When the polarity of horizontal sync. is
positive, this pin is "LOW".
(Refer to circuit diagram Fig-30)
Pin 36 is the input of horizontal synchronous signal,
whose polarity is positive.
In order to get a constant width of horizontal sync.
pulse, MULTIVIBRATORS 0515a is introduced,
horizontal sync. is fed to signal (pulse is 6 us) is fed
to pin 36 of 0512, the width of the output signal on
pin 13 of 0515a is decided by R559-C516.
Pin 33 is RESET pin, it connect to pin 3 of RESET IC
Pin 37 is the input of vertical synchronous signal
0506.
whose polarity is positive.
Function of 0506 (Monolithic IC PST518A) is 3.38 VOLTAGE SUPPLY
accurately resetting the system after detecting voltage
(Refer to circuit diagram Fig-38)
at the time of switching power on and instance power The voltage supply of the micro board has its own
off in the microprocessor circuit. regulator which differ from the regulator of the main
board.
Pin 13 is the G+SYNC. signal detection pin for 0512.
When G+SYNC. signal input, this pin is "LOW". The +12V and +5V supply lines to the microproces-
sor circuit are fed via the network 0511-0514-0503-
Pin 14 is the H+V signal detection pin for 0512.
When H + V signal input, this pin is "HIGH".
A multivibrators 0515b is introduced to achieve the
detection function. Once the vertical sync on pin 1 of
0515b is greater than 40Hz, pin 5 of 0515b is
"HIGH", the values ofC558-R587 are selected so as
to re-trigger the multivibrators.
0501-0502-0504 and some discrete components.
R556 allows fine adjustment to make the "TEST PIN"
voltage
at + 12V. The
+
5V is derived from
+
12V via
zener diode 0504-R558 and C154.
The power (12V) of the LEO is fed from pin 2 of P505
via R731.
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3-31
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