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(3) Start/stop control circuit
1
Outline
The ON/OFF state of the power is detected to control start/stop of
each circuit.
The DC power PWB supplies the power voltages (VB = +24V, VC =
+10V, VD1 = 5V, VD2 = 5V).
When the power voltage reaches the specified level, the operation of
each circuit is started. Before the power voltage falls below the
specified level, the operation is stopped, preventing malfunctions.
Q210
DTC114YK
3
R277
150J
10K
FW
2
CN107-13
47K
1
+12V2
R276
R289
68KJ
910J
3
5
+
2
4
-
IC206A
12
LM339NS
+
C111
1U/
GND2
50V
ZD103
HZ6A1
+12V2 +5V2
R281
R284
22KJ
10KJ
11
-
10
+
IC2060
R282
R283
LM339NS
10KJ
10KJ
2
Operation
a. POFA generation circuit (Power voltage detection circuit)
This circuit detects ON/OFF of the power and the power voltage.
The Immediately after turning on the power, when the AC input
voltage is abnormally low, in case of an instantaneous service
interruption, in the transient period after turning off the power, the
DC power is low and unstable.
When the DC power voltage falls below the specified level, the
circuits will not operate normally. Especially immediately after
turning on/off the power, data transmission is performed between
the EEPROM (IC118) and the CPU (IC107). @IN1/ = If the power
voltage is +5V lower, data transmission is not performed.
To prevent against this state, ON/OFF of the power is detected in
an early stage and informed to the CPU; data transmission be-
tween the CPU and the RAM and the operations of the circuits are
started after the DC power voltage reaches the machine
operatable level; data transmission between the CPU and the
RAM is completed before the DC power voltage falls below the
machine operation impossible level; and the operations of the
circuits are stopped. (Data transmission between the CPU and the
EEPROM is allowed unless the +5V3 voltage does not fall.)
The POFA signal informs the CPU of ON/OFF of the power and
the DC power state in the circuit. The POFA is driven HIGH (+5V)
when the power is turned on and the DC power rises above the
specified level. When the power is turned off, it is driven LOW
(0V) before the DV power voltage falls below the specified level.
+24V1
1
D212
R287
DAN-217
91KJ
R278
2
7
+
1
300J
5
3
-
IC2068
R288
+
LM339NS
36KJ
C110
3.3U/
50V
GND2
GND2
+5V2
13
R292
Q211
300J
DTC114YK
10K
IA
47K
9 – 12
+12V1
R286
R280
D213
2.2KJ
220KJ
DAP202K
1
R290
R285
39KJ
10KJ
3
9
+
14
+
8
-
C109
IC206C
C308
2
3.3U/
LM339NS
102K
50V
Q212
DTC114EK
10K
DCH
2
(1-5D)
C309
10K
102K
+5V2
R294
Q213
2.2KJ
3
DTC114YK
10K
POFA
2
C310
223Z
47K
1
+5V2
RES\
(1-5C)
C317
223Z
R292
3
300J
1
POFA\
(1-5D)
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