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10
BR
NIE
i
oT
completed
and the counter
reaches
its initial
posi-
tion.
The inhibition
circuit
comprises
transistors
V61
and V62.
For inhibition,
V61
becomes
conducting
and blocks
diode
D63.
When
inhibition
ceases,
V61
is cut off.
V62 then
becomes
conducting
and helps to
cut off V61.
4,5
DC VOLTAGE REGULATOR +6V (+5V) (TTL)
See appendix
1. In principles
the +24V supply
is
switched
on and off at a rate that
provides
the de-
sired +6V (+5V).
The switch
regulator
is built
up
around
bistable
flip-flop
FFSR which at IC17/3
switches
the current
to coil L] via V14 and V38.
On
and off is controlled
at IC17/1
and IC17/4 respecti-
vely.
IC17/5 is kept high via V20 as long as the
voltage across
C44 is more than 0.6V lower than the
reference
voltage at the emitter
of V20.
The negative
trigger
pulse
(about O0.5s),
from the pulse shaping
circuit
I1C21/8 end I1C20/11,
which
is obteined
at po-
wer on,sets
FFSR
to ON making V38 to cunduct.
When
the voltage
at the base of V20 goes
sufficient
high,
V20 is cut off and FFSR changes
state.
After a cer-
tain time,
depending
on charging
and recharging
of
C33 controlled
by 1C€22/8,
the FFSR
is again
set to ON.
aoe) DG voltage Cegulator shutett,0e-an
The switch
regulator
is started
or stopped
via diode
D26.
The delay circuit
R93, C42 controls
that any re-
triggering
of the FFSR
flip-flop
at short
power
fai-
lures,
is prevented.
The DC-ON
circuit
which monitors
power
failures
and
controls
the current
grow
up,
is
built
up around
IC20/6 and V18.
The switch
regulator
turns
off/on the PR signalling
and the PI control
is
monitored
across
R68 by IC20/6.
The level across
R68
follows
the 24V supply.
When
the level
goes
high the
switch
regulator
starts
and PR goes
high.
When the DC-ON
push button
is depressed
24V is supp-
lied to the base of V18 via R122 and R125 in parallel.
The V18 emitter
then goes
high.
After
a certain
time
when
the regulator
has come
into
function,+5V
is supp-
lied to the collector
of V18 wherewith
V18 acts
as
an emitterfollower.
When
the DC-ON
push-button
is
released,
the level
at the collector
of V18 is cont-
rolled by the voltage divider D28 - R125 and R124.
pels tenatlaes R124 shall be adjusted so that I1C20/6
goes high
when the supply voltage drops to 19.2V.
With diode D35 positioned
at ®, V18 will act as an
emitter
follower
from the start.
This means
that
1C20/6 goes low as soon as the 24V supply reaches
25V (192V at the primary side of Tl). The hysteresis-
voltage
of 0.8V in IC20/6 causes,
together
with
zener diode
D28,
the right
on-
and off levels.
Note: Automatic
DC-ON can not be used in DC-variants.
4.6
SWITCHED CURRENT CONTROL
FOR THE STEPPER
MOTOR
(TTL)
The regulator
is built
up around
FFCC
(bistable
flip-flop)
which
controls
the current
to the motor
via IC13/8.
The current
to the motor
flows
through
R112,
R113.
When
the current
through
these resistors
reaches
3.2A (adjusted
with R127) the
voltage drop
is detected by vis which opens
and resets
FFCC. The
negative
trigger
pulse
(about 5s)
which
is then
obtained
from the pulse
shaping
circuit
IC16/12
and
1C19/6, again sets IC17/8 high and so on. During
TF and TP IC16/8 is high enabling
the pulses
from
FFCC to pass via 1C13/9 and the selected
drive in-
put from the stepper motor
counter
(see also sec-
tion 4.3.2).
4.7
POWER CONTROL
FOR THE STEPPER
MOTOR
This
circuit
prevents
the stepper
motor
from damage
if a drive pulse becomes
too long or is repeated
too rapidly on one winding.
This
can
happen
either
if TF or TP becomes
too long or if the stepper mo-
tor counter
stops
in a certain
position.
4.7.1
TTL - Version
1
If,
for example, V33
feeds ,C27 is charged
during
the negative
pulses
via D17 and R103 and is dis-
charged
in the pauses
via R106.
R103 and R106 are
so chosen
that the point
between
these
resistors
is lowered
at an appropriate
time
constant
as long
as
feeding
continues.
The level
at this point is
compared
with
a reference
voltage
at the emitter of
V19 via D21. At the moment
when the base of V19
goes
enough
low, V19 opens
V37 which
is fed back to
V19 via D24, V37 now supplies
approx 4A through
F1
which
blows
after about
30ms.
R121
and D34 compen-
sate
for different
variations
in the +24V supply.
tor of transistor
V23, Adjust
the 25V supply
to
25t0V by means
of a variable
transformer.
The vol-
tage across
V23
shall
then
be 3,95+0.,05V
4.7.2
TTL -
Version
2
If, for example,
V33
feeds , C27 is charged during
the negative
pulses
via R103 and is discharged
in
the pauses.
The level
is lowered
at an
appropriate
time constant
as long as
feeding
continues.
The
level
at C27 is compared
with
a reference
voltage
at the emitter
of VI9 via D21. At the moment
when
the
base
of V19
goes
enough
low,V19
opens
V37 which
is fed back
to VI9 via D24.
V37 now
supplies
approx
4A through
Fl which
blows
after
about 30ms.
If the
switching
system
fails,
C50 is charged
so high that
V4] starts
to conduct
and opens
V19.
4.8
FAN AND WINDING MOTORS
The
fan and winding
motors
are driven
via V36
(V48,
V52) and IC20/3. The motors start at PR, IC21/4 and
DC-ON
(DC-ON)
and are stopped at backward
feed via
diode
025 and transistor
V16
(D56,
V39).
There
is
a 40ms
delay at power
off, R59,
C41
(R113,
C24).
i
Switch
S6 controls
the winding motor direction.
Using switch
S7 the motor
can
be switched
on/off.
At off the motor load is substituted
by a resistor
load.
5
SERVICE
5.1
MECHANICAL
CHECKS AND ADJUSTMENTS
A
Removing
punch/feed
unit
Unhook
the wire
from arm A.
Remove
connector
B from the punch/feed
unit.
Remove screws
C and carefully lift out the
punch/feed
unit.
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