Philips PM 3266 - Page 98

3.
1.5.7.
Storage
Section
Block
Diagram
Description
The
block
diagram
of the
storage
section
is shown
in Fig.
3.1.
The
voltage
waveforms
that
are
applied
to
the
storage
electrodes
have
already
been
described
in
the
previous
section.
The
storage
electrodes
are
connected
to
the
outputs
of
their
appropriate
amplifiers,
i.e,
the
fast
mesh
is
connected
to
the
FAST
MESFI
AMPLIFIER
and
so
on.
The
FRONT
MESH
AMPLIFIER
and
the
FRONT
MESH
PREAMPLIFIER
are
of
special
interest.
If
the
output
voltage
of the
FRONT
MESH
AMPLIFIER
is
"high",
the
front
mesh
is
connected
to +500
V; if
the
output
voltage
is
low
,
then
the
front
mesh
potential
is
that
of
the
output
voltage
from
the
FRONT
MESH PRE-
AMPLIFIER.
The
amplifiers
receive
their
input
signals
from
the
STORAGE
LOGIC.
This
block
can
be subdivided
into
the
following
functional
sections:
—
pushbutton
switch
detector
—
timer
—
auto-erase
timer
—
dual
oscillator
—
ETB
and
BTB pulse
generator
—
stabilisation
pulse
generator
—
input
switching
for
storage
amplifiers
PUSHBUTTON
SWITCH
DECODER
This
block
is operated
by
the front-panel
storage
control
pushbuttons:
STORE,
WRITE,
and FAST
(S24A,
S24B and
S24C).
Depending
on
the
combination
of the
pushbuttons
selected,
one of
the four
functional
outputs
FAST,
WRITE,
STORE
and NON-STORE
is
activated.
A faulty
pushbutton
combination
automati-
cally
activates
the
STORE output.
The decoder
is arranged
in
such a
way that
a further
selected
pushbutton
combination
does not
affect
an
erase/preparation
-
write
-
transfer
cycle that
is
already in
progress.
Only at the
end of the
cycle
can the new
pushbutton
combination
become
effective.
TIMER
In
the WRITE
and FAST
modes this
block
generates
output
pulses for the
timing
of the
erase/prepare
cycles.
If the ERASE
pushbutton
(S25)
is released, or
if the
AUTO ERASE
TIMER
generates
an output pulse,
the
TIMER
generates
pulses on separate
outputs after 100 ms,
600 ms, 900 ms,
1200
ms and 1500
ms.
AUTO-ERASE
TIMER
In
the FAST
mode
this block
generates pulses if
the VIEW TIME
control
(R16) does not occupy
the MAX
position.
These
pulses trigger
the TIMER
in
the same manner as after
release
of the ERASE
pushbutton. The
pulses have a
duration
of
1
ms and
a repetition
rate that is
adjustable
by means of
the VIEW
TIME control
of
between 3
s and
8 s. In other
words,
after a view time
that is adjustable
between
3s
and 8 s the display
is
erased and
another
picture is
written
if the time-base
is triggered.
DUAL
OSCILLATOR
The
dual oscillator
receives
a
100 Hz
square wave from
the 100 Hz
MASTER
OSCILLATOR.
This
oscillator
is
not synchronised
by the
mains
supply voltage.
One output from
the DUAL
OSCILLATOR
produces
a
100 Hz
square
wave of which
the
duty cycle can
be adjusted
between 0 and
30
% by the PERSISTENCE
control
(R16).
This signal
is used
to pulse the front
mesh
in
the
variable
persistence
position.
The other output
produces
a 100 Hz
square
wave of which the
duty cycle
can be adjusted
between
0 and 80
%
by the INTENS
control (R14).
This signal is
used
to
pulse
the flood
gun accelerator
in the
STORE mode in
order
to adjust
the brightness
of
the recorded
waveform.
ETB PULSE
AND BTB
PULSE GENERA
TOR
This block
generates in
the FAST
mode pulses at
the end of the time-base
sweep
{ETB
pulse) and at the
beginning of the
time-base
sweep (BTB pulse).
At one output
a
positive-going
pulse
appears
at
the
beginning of
the sweep
of
the
selected time base, and
at
the
other output
a positive-going
pulse
appears
at
the
end of the sweep of
the selected
time-base.
STABILISATION
PULSE
GENERATOR
This block
operates in
the
FAST
mode and
generates
"needle" pulses with
a
frequency
of 1 50 Hz and
a duty
cycle of 0.07 %. These
pulses are
applied to the fast mesh of
the c.r.t.