Philips pm3232 - Vertical Amplifiers

78
3.2.3.S.
Barrel
&
pin cushion distortion (R812)
—
Set
TIME/cm switch SK2 to
1 ms
and
TIME/cm potentiometer
R2
to
CAL
—
Set
AMPL
switch
SK17 to
10
mV/cm and AMPL
potentiometer R4 to CAL,
-
Depress BEAM
SELECTOR
switch A SK14
—
Set
AC-O-DC
switch SK16 to
DC
—
Apply
a
sine-wave
signal
of
1 Vp.p,
2
kHz,
to
Y/\
input
socket BU3
Use an
insulated
screw-driver.
Be
careful not to
make any
short-circuits.
—
Check that
the displayed
vertical lines are
straight.
If necessary,
readjust
potentiometer R812
(Fig.
3.11.)
3.2.3.6.
Brightness (R711, R801,
R802)
1500 V Use a
well-insulated
screw-driver
to
protect
both
yourself
and the
circuitry.
—
Switch the
instrument on at
least
15 m'mutes
before
starting
this check
—
Depress
Y/^
switch SK4,
+
switch SK8,
AUTO
switch SK10
and
BEAM
SELECTOR
switch A SKI
4
—
Set
AC-O-DC
switch SK16 to 0
“
Set
AMPL switch SK17 to
.1 V/cm
—
Set
INTENS
potentiometer
RIO
for
low brightness
—
Set
TIME/cm
switch
SK2 to
1 ms and
TIME/cm
potentiometer
R2
to CAL
—
Check that
the time-base
line shows a
constant
brightness over the
entire
length; if
necessary,
readjust
potentiometer
R711
(Fig.
3.12.)
“
Check that the
brightness
remains constant in
all other
positions
of TIME/cm
switch SK2
—
Depress
AC
switch SK1
1
—
Set
TIME/cm
switch SK2 to
1 ms
—
Turn INTENS
potentiometer RIO
fully
clockwise
—
The
spot
must just be
visible; if
necessary, readjust
potentiometer R801
(Fig. 3.1
1.)
—
Depress AUTO
switch SK10
—
Set
INTENS
potentiometer
RIO to
90°
from
itsleft-hand
stop
—
Check
that
the time-base
line
Is barely visible;
if necessary,
readjust
potentiometer
R802
(Fig. 3.1
1.)
3.2.3.7.
Focus
correction
—
Depress
AUTO
switch SK10
and
BEAM
SELECTOR
switches
A
SK14
and B
SKI
5
-
Set
AC-O-DC
switches
SK16
and SK19
to
0
-
Set
AMPL
switches
SK17
and SK18
to
.1 V/cm and
AMPL
potentiometers R4
and R5
to
CAL
--
Shift
the
time-base
lines
on
to
the
horizontal
central
graticule
line
with the
aid of
POSITION
potentiometers
R11
and R12
-
Rotate
FOCUS
potentiometer
R9
from fully
anti-clockwise to
fully
clockwise and
check
that this
does
not
cause
the
time-base
linc> to
shift more than
2 mm
3.2.4. VERTICAL
AMPLIFIERS
3.2.4.1. General
information
The
adjustments
of
the
vertical
amplifier
channels
Ya
and
Yb
are
identical.
The
knobs,
sockets
and
adjusting
elements of
channel
Yb
are
shown in
brackets
after
those of
channel
Y^.