Philips PM 3266 - 3.4.6. Cathode-ray tube circuit

150
—
Apply
a sine-wave
voltage
at a frequency
of
approx.
100
kHz
to input
A
—
Set the
AMPL
controls
to
obtain
a trace
height of
7,4
DIV
—
Apply
a
sine-wave
voltage
at a frequency
of
approx.
50 Hz to input
B
—
Depress
push-button
EXT
X
DEFL of
the
X deflection
controls
(S2)
—
Depress
push-button
B of the
main
time-base
trigger-source
controls
(S22)
-
Set the channel
B
AMPL
switch
and
X AMPL
control
to obtain
a
display
width
of
9,4 DIV.
—
Check
that
the
edges of the display
lie within
the hatched
area shown
in
Fig.
3.25.
;if
necessary,
readjust
potentiometer
R2103
on
the
X-amplifier
unit.
—
Remove
the
input
signal.
3.4.6.5.
Intensity
(unit
11)
—
Depress
push-button
A of the
display-mode
controls
—
Depress
push-button
DEL'D
TB of the
X deflection
controls
—
Turn
the
INTENS
potentiometer
clockwise
-
Set
the
MAIN
TIME/DIV
switch
to 1
ms and
the DEL'D
TIME/DIV
switch
to
1
jus
—
Depress
push-button
0
of the
signal-coupling
controls
—
Depress
push-button
MAIN
TB of the
delayed
time-base
trigger-source
controls
-
Check that
there
is
a
barely
visible
dot
at the beginning
of the
trace.
If necessary,
readjust
potentiometer
R2064
on the
Z
amplifier unit.
3.4.6.6.
Intensity
ratio
(unit
8)
-
Depress
push-button
A of the
display-mode
controls
(SI
)
-
Depress
push-button
MAIN
TB of the
X deflection
controls
(S2)
—
Turn
the
DELAY
TIME
control
(R1
)
to
5.0
(mid-p>osition)
—
Set
the MAIN
TIME/DIV
switch
to .2
ms and the
DEL'D
TIME/DIV
switch
to
50 /its
—
Depress
push-button
AC of
the channel
A signal-coupling
controls
-
Apply
a sine-wave signal
at
a frequency
of 100 kHz
to
input
A
—
Set the
display-height
to 6 DIV
-
Set the
INTENS
potentiometer
to
a position
90°
from
the anti
clockwise
stop; see Fig. 3.26.
—
Check
that the
trace of the
main
time-base
generator is
barely visible
over the
entire
screen and
that the
part determined
by the delayed
time-base
generator
is more brilliant. If
necessary,
readjust
potentiometer
R1537
on the
time-base
unit
-
3.4.7.
Balance adjustments
The
adjustments of
the vertical
channels
Aand
B are identical.
The
knobs,
sockets and
adjusting elements
of
channel B are
shown
in brackets
after those
of channel
A.
The balance
adjustments
influence
one another
and must,
therefore,
be readjusted
in
the order
in which
they
are
described.
3.4.7.
1.
0-DC
Balance
(Attenuator
unit)
—
Depress
push-button
A (B) of
the display-mode
controls
(SI
)
—
Set the channel
A
(B) AMPL switch
to 5
mV/DIV
and the
vernier
control
to CAL.
-
Centre the
time-base
line, using the
POSITION
potentiometers
—
Set the
channel
A (B) signal coupling
switch
from 0 to
DC
—
Check
that the
trace does not jump; if
necessary,
readjust potentiometer R1
24
(Ch. A) or R174 (Ch. B)
on
the attenuator
board.
3.4.
7.2. Attenuator
balance
(Attenuator
unit)
—
Depress
push-button
A (B) of the display-mode
controls
(SI
)
—
Depress
push-button
0 of the channel
A (B) signal-coupling
controls
—
Centre the
time-base line,
using the
POSITION controls
—
Turn the
AMPL switch
between
5
V/DIV and
10
mV/DIV
—
Check that the
trace
does
not jump more than
0,1
DIV;
if necessary,
readjust
potentiometer R129
(Ch.
A)
or
R179 (Ch.
B) on the attenuator
board.