Philips PM 3206 User manual

PHILIPS
L.F.
OSCILLOSCOPE
P M 3206
66 403
13.2-10
1i465j01

1
i
r
i
~
PHILIPS
0
.,
PEM 747
L.F.
OSCILLOSCOPE
P
M
3206
66 403
13.2-10
1/465/01
Manual

2
Contents
GENERAL
PART
I.
Technical
data
II .
Accessories
DIRECTIONS FOR
USE
5
8
II I.
Installation
9
A.
Adjustment to local mains voltage
9
B. Earthing
10
C.
Connection to the mains
10
IV.
Operation
10
A.
Knobs
and
sockets
and their functions 10
B.
Switching on
10
C.
Input circuit of the
vertical amplifier 10
D. Making the
voltage shape visible
11
E.
Determining thetime 13
F.
Voltage
measurement 13
G.
Horizontal deflection
with an external voltage
13
H. Horizontal
deflection with
an
internal sinusoidal voltage
at mains frequency
14
I.
Horizontal
magnification 14
J. Brightness modulation
14
K.
Use
of the
calibrating
voltage
15
SERVICE DATA
V.
Description of the
working
principle 17
A. Introduction
17
B. Attenuator
17
C. Vertical amplifier
17
D. Trigger pulse shaper
18
E. Time -base
generator 18
F.
Horizontal amplifier
19
G. Cathode-ray tube
circuit 20

3
H. Calibration source
21
J. Power supply
21
VI.
How to gain access to the components
28
A. Removing
the cabinet
28
B.
Removing the knobs
29
C. Removing the protective cap and
the
measuring
graticule
29
VII. Replacing component parts
30
A. Replacing
the thermal fuse
30
B. Replacing the safety fuses
30
C.
Replacing the cathode-ray tube
31
VIII. Survey of adjusting points with relevant measuring equipment
32
IX.
Adjustments
34
A. Pre -adjustments and checks
34
B. Cathode-ray tube circuit
35
C. Vertical amplifier
35
D. Calibration voltage
38
E. Horizontal amplifier
38
F.
Time -base
generator
39
X.
Information
on fault-finding
43
XI.
List
of
component
parts 44
A. List of
mechanical
parts
44
B. List of electrical parts 46

4
List of Figures
1
Rear view
9
2 Controls
and their functions
11
3 View
of
side
controls
15
4 Block
diagram
of the oscilloscope
25
5
Removing
the
panels
28
6 Removing
the
knobs
29
7
Removing
the protective cap
and the
measuring
lattice 30
8 Turning the
cathode-ray tube
31
9 Response curves
37
10 Front view
S0
11 Right-hand
side
view
51
12 Rear view
52
13
Left-hand
side
view
53
14 Printed
-wiring
board
A
54
15
Printed
-wiring
board D 56
16
Printed
-wiring
board
E
55
17
Printed
-wiring
board F 57
18
Printed
-wiring
board
G
58
19
Printed
-wiring
board
H 59
20
Printed
-wiring
board
J
60
21
Printed
-wiring
board
L
61
22 Printed
-wiring
board
O 62
23
Printed
-wiring
board
P
63
24 Y Amplifier 65
25 Time -base
generator and
trigger pulse shaper
71
26
X
Amplifier and
cathode-ray
tube circuit 77
27 Supply part 83
28 Circuit diagram 85
IMPORTANT
In correspondence concerning this apparatus, please quote the type and
serial numbers
given on the type plate at the rear of the apparatus.

5
GENERAL
PART
Technical
data
0
Properties expressed in
numerical values with tolerances stated
are
guaranteed
by us.
Numerical values
without tolerances are
given
for
information purposes
omy
and
indicate the
properties of an
average
apparatus.
A. CATHODE-RAY
TUBE CIRCUIT
1.
Cathode-ray tube
a. useful
screen surface
b.
deflection
c. total
acceleration
voltage
d.
brightness control
2.
Brightness modulation
a.
voltage
required
b. input impedance
3. Mechanical
beam suppression
4.
Measuring
graticule
D10-12GL
8 x
6
cm
(31/a"
x
2 3 / $
")
symmetrical
2800 V
d.c.-coupled
30 V for frequencies up to 1 kc/s
600
kS2//25
pF
The be am is
suppressed
when a plug is
inserted
in
an
input socket. If this socket is subsequently
earthed,
the
trace reappears.
8
x
6 cm,
smallest
subdivision
2 mm. The
graticule illumination can be
regulated.
B. Y
AMPLIFIER (VERTICAL
DEFLECTIOl~
1.
Deflection factor
2. Frequency response
13
calibrated
steps :
0.002 -
0.01 - 0.02 - 0.05 -
0.1-0.2-0.5-1 -2-5-10-20-SOV/cm.
Tolerance ~ 3 %. Continuous adjustment is
possible between the steps (not
calibrated).
0-100
kc/s
(max.
drop 3 dB) for sensitivity
from -~-
2 mV/cm.
0-300 kc/s (max. drop
3
dB)
for
sensitivities
from
10
mV -50 V/cm.

6
The
band width is almost constant in
all
positions of the step
attenuator, but varies
slightly when the continuous
attenuator is
moved.
3.
Overshoot
4. Input
a.
input resistance
b. input capacity
c. max. permissible
d.c. voltage with
a.c.
coupling
G
CALIBRATING VOLTAGE
<_ 0.5 %for pulses with rise
times
>_
30 ns.
asymmetrical, d.c. or a.c.
coupled (switchable)
0.5
MS2
positions
0.01-0.02 and
0.05
V/cm: <_ 50
pF
other
positions: < 20
pF
300 V
(SOCKET "CAL.")
square -wave
voltage of
40
mVp_p (~
1 %),
frequency
equal to the mains frequency
D.
X
AMPLIFIER
(HORIZONTAL
DEFLECTION)
1.
Deflection factor
2.
Frequency
-response curve
3. Input
a. input impedance
b. max. input voltage
4. Horizontal -deflection
voltages, by selection
5. Magnification
a.
with horizontal
deflection
by means of
the
internal
time -base
b. with
horizontal
deflection by
means of
an
external voltage
1
V/cm
attenuation with continuous control and/or
fi
xed
attenuator 1 : 10 (2 input sockets)
0-300
kc/s
(-3 dB)
asymmetrical
1 :
1
-input: 100 k52//30
pF,
1 : 10 -input: 1.1
MS2//6
pF
1 : 1 -input:
100
V p
_ p ,
1 : 10 -input: 700
Vp_ p
a.
the internal time -base
voltage
b.
an
external voltage
c. an internal voltage
with
mains frequency
x
1 or
x 5, tolerance ~ 3 %,
with
respect to
the
"x
1" position
continuous
up
to 5
x
8 cm

7
E.
TIME
BASE
GENERATOR
1.
Sweep
times
2. Modes
of operation
3.
Triggering
a.
sensitivity, internal
b. sensitivity,
external
4.
Trigger level
5.
Output
voltage at
socket
"45 V ice/"
F.
SUPPLY
18 calibrated
times : 2 -
5 - 10 - 20 - 50 - 100 -
200-500µs/cm, 1 -2-5-
10-20-50- 100-
200 - 500
ms/cm,
1
s/cm, tolerance ~ 3 %.
When expanded
via the horizontal
amplifier
(5 x) the
shortest sweep time is 0.4
µs/cm. The
sweep times
can be
varied
continuously between
steps (not calibrated).
a. free -running
b. triggered
by selection, internally +
or — (L.F. or
H.F.),
externally -~
or —
(d.c.
or
H.F.) or internally
with
the mains
frequency ~-- or —
0.5 cm trace
height for frequencies
>_
1 c/s
1
Vp_p
for
frequencies from 0-300 kc/s input
impedance: 1
M52//40 pF
Max. external
triggering
voltage
is
3 V p
_p.
Trigger
level can be continuously adjusted
inter-
nally
across 6 cm
(2 3
/s")
picture height; exter-
nally across 12
V.
sawtooth
voltage of 42
Vp_p,
d.c. level -~-
20 V.
the
load
may be max. 0.1
MS2//35
pF,
Can
be
changed
over for mains
voltages of
110-127
and
220 V. The mains frequency
may
be
40-100 c/s. With mains
frequencies
G
50 c/s,
the
mains voltage must not exceed
the nominal
value.
The power consumption
is 135 W.
G.
INFLUENCE OF
MAINS -VOLTAGE
VARIATIONS OF ~ 10%
The
vertical and the
horizontal -deflection sens-
itivities
(sweep times) slightly vary at
mains
voltage
variations. The calibrating voltage,
however,
remains constant.

g
H. MECHANICAL DATA
Dimensions
height
30 cm
(1113/16")
width
21.5 cm
(8
x
/16)
depth
45 cm
(1'
S 3 /
a ")
Weight 14 kg
(30.86 lbs.)
Accessories
1
mains cable
1
manual
(Directions
for Use ~-- Service Notes)
1
measuring
cable,
length approx. 1 m,
with 4 -mm plugs at each
end.
i
i

9
DIRECTIONS FOR
USE
Installation
A. ADJUSTMENT
TO
LOCAL
MAINS
VOLTAGE
The apparatus can be
adjusted,
by means
of
a
voltage
adapter, to
mains
voltages of
110,
127 or 220 V.
The required
value
can be
read through
the
opening
in the rear
panel
(Fig. 1).
Adjustment to other mains voltages is
effected as
follows:
a. Remove the screws
"A" and detach the rear
panel.
b.
Pull out the adapter slightly, turn it until the
correct voltage is
upper-
most
and push
back.
c. Fit the
rear panel again.
BU
9
BU 10
BU
8
N
Fig.
1. Rear view
i
VL 2
i

IO
B.
EARTHING
The apparatus
should
be
earthed
in conformity with local safety
regulations. This can
be
done:
a. via one of the earthing sockets at the front (see Fig. 2), or
b. via
the
mains
cable
when the apparatus is equipped with
athree-core
mains cable fi
tted
with
a
plug with an earthing contact.
Double leads
may give rise
to hum and must
therefore be
avoided.
C. CONNECTIONS TO THE
MAINS
a. Make sure that the
mains
-voltage adapter is
correctly adjusted.
b.
Earth
the apparatus.
c. Set the mains
switch
"ILEUM." at "0".
d.
Connect
the
mains input socket ("N", Fig. 1) to
the
mains with
the
cable provided.
Operation
A.
KNOBS
AND
SOCKETS
AND THEIR
FUNCTIONS
Please refer to Fig. 2.
B.
SWITCHING
ON
•
Switch
on
the apparatus by turning
the
control
"ILEUM."
clockwise.
This control also
serves for graticule illumination.
C. INPUT
CIRCUIT OF THE
VERTICAL
AMPLIFIER
The signal
to be
tested
is connected
to
the socket marked "Y
AMPL.".
When
the
switch
"AC/DC"
is
in
the position
"DC"
the amplifier is
d.c. coupled to
the input. In
the position
"AC" a
blocking
capacitor
is interposed
between the input
and the
amplifier.
L
L
Y
1
1
1
1
1
1
1
1
1
1

11
D.
MAKING
THE
VOLTAGE
SHAPE VISIBLE
1.
Preliminary adjustment
a.
Set all knobs to the
positions
indicated in Fig. 2.
b.
Turn
the
knob
"TRIGG.-STAB." clockwise
until
the time -base
line
appears.
c.
Adjust the line to the
middle of the
screen by means of the knobs
"FX~"
and
«~
YT
„
R9
R10
SK
3
SK41R8~_
SK
2
R7
SK 6
/
SK
5
BU
1
Fig.
BU
2
R13
BU 3
BU
41SK
10
BU 5 BU 6
2. Controls
and
their functions
RIISKI
R2
R3
R4
R5
R11
SK
7
SK
8
R 1215K 9
BU 7
R9
Trigger level
R10 Trigger stability
SK3 Selection of horizon-
tal deflection voltage
SK4/R8
Magnification x 1
or
x
5
in position /~/
of SK3
Continuous
control in
other positions
of
SK3
SK2 Step
control vertical
sensitivity
R7 Continuous
control
vertical sensitivity
5K6
Sensitivity increase
switch
SK5
AC/DC
selection for
the
input
BU1 Input
to
the
vertical
amplifier
BU2 Earth
socket
R13 Fine balance
control
for vertical
amplifier
BU3
Calibration voltage
BU4/SK10 Input for
exter-
nal trigger
BUS/BU6 Inputs to the
horizontal amplifier
BU7
Earth socket
R12/SK9
Continuous
con-
trol
of
sweep
times
SK8
Setting
of calibrated
sweep
times
SK7
Selection of trigger
voltage
Rll Astigmatism
RS Brightness
R4
Focusing
R3
Vertical shift
R2
Horizontal shift
Rl/SK Mains
switch
Lattice
ilium.

12
d. Adjust
the
brightness and
the
definition
of the picture
with
the knobs
"INTENS.", "FOCUS"
and "ASTIGM.".
Stationary pictures of
intense
brightness
may
cause permanent damage if
they areon the
screen for
a
long
time.
2.
Time -base
internally
triggered
a.
Set
the
switch "TRIGG." to
the
position "+HF" or "—HF". Use
the positions "-{-LF" and "—LF" at low frequencies only
(<
approx.
30 c/s). At very low frequencies (0-1 c/s) external
triggering must
be
applied
(see the following
section).
b. Make the time -base line visible as
described under "Preliminary
adjustment".
c. Set
the
"AC/DC" switch to
the
desired position.
d. Connect
the voltage
to be tested to the socket "Y AMPL."
and
adjust the picture height to the
required
value by means
of
the
switch "Y AMPL." (or with the continuous control if
required).
The vertical sensitivity,
however,
is
only
calibrated when the conti-
nuous control
is
in
the
position
"CAL." (turned
fully
clockwise).
e. Adjust to
the
approximate sweep time
required
with
the
switch "/w"
~. Turn the knob marked "TRIGG.-STAB." anti
-clockwise
until
the
trace
just
disappears (the knob "TRIGG.-LEVEL" is still
turned
anti
-clockwise).
g. Now turn the knob "TRIGG.-LEVEL" clockwise until
the time -
base starts
and
the
trace
becomes
visible
again. This can
now be
further adjusted until
the time -base
starts at
the
desired
level of the
voltage under test.
h. Farther
adjust the sweep time
with
the
switch "/v~/"
if necessary.
i. Adjust the knob "TRIGG.-LEVEL" and/or "TRIGG.-STAB."
a
little further
if
necessary.
If
desired,
the picture can now be
magnified
in
the horizontal direction by means of
the
control
"X DEFL.".
3.
Time -base externally
triggered
Connect
the
external
trigger
voltage to the socket "EXT. TRIGG.".
As soon as
a plug is
inserted
in this socket,
the internal trigger
voltage
is switched
off
and
the external
trigger voltage is connected to
the input
of
the trigger
pulse shaper. For triggering with
frequencies of over ap-
prox. 30 c/s, set
the switch
"TRIGG."
to
the position "~-HF" or "—HF".
When
the switch
"TRIGG."
is in
the
position "~-LF" or
"—LF", the

13
input circuit for
the
external
triggervoltage
is d.c. coupled acid can be
triggered
with very
low frequencies or with
a direct
voltage. For the
rest
proceed as for
internal triggering.
4. Time
-base
internally
triggered with
the mains frequency
Set the
switch
marked
"TRIGG." at
the
position "-~
50 Hz"
or "-50 Hz".
Then proceed
as described in section
2
"Time -base internally triggered".
E. DETERMINING THE TIME
The sweep
time
per
cm
can
be determined
from the position of
the
knob "M/ ".
When
the picture
is magnified
5
x in horizontal
direction (see section I
"Horizontal
magnification") the sweep
time
per
cm is
5 x smaller than is
indicated
by these knobs.
F. VOLTAGE
MEASUREMENT
When the continuous control "Y
AMPL." is
in the position
"CAL."
(turned fully
clockwise), the value of
the voltage connected
to the
socket
"Y AMPL." can
be
determined
immediately from
the picture height and
the
position of
the step attenuator "Y
AMPL."
Switch "NORMAL
-2 mV" enables
the sensitivity of
the amplifier to
be
increased
when the attenuator is
set to
maximum sensitivity. Thus with
switch
"Y AMPL." at "10
mV/cm"
and
switch
"NORMAL -2
mV" at
" 2 mV" the sensitivity is 2
mV/cm.
For calibration at the vertical
sensitivity see chapter
IV.
K
"Use of
the
calibration
voltage".
G.
HORIZONTAL DEFLECTION WITH
AN EXTERNAL
VOLTAGE
The time -base generator is switched off when
the switch
"X DEFL."
is at the position "EXT.". Both
the
vertical and
the
horizontal
deflection
can then
take place
with
an external
voltage, so that,
for
example,
frequency measurements can
be
carried
out
with
the aid
of Lissajous
fi gures.
The
external
voltage
for
horizontal deflection is connected
to
one of the
sockets "X AMPL." ("10
V/cm"
or "1
V/cm"). The horizontal
amplitude
can be
varied with
the continuous control "X DEFL.".

14
H. HORIZONTAL DEFLECTION WITH
AN IN TERNAL
SINUSOIDAL
VOLTAGE AT MAINS FREQUENCY
For
this purpose
set the
switch
"X
DEFL."
at the
position "50 Hz".
The horizontal amplitude
can
be
varied with
the continuous
control
"X DEFL.", as in position "EXT."
the
time -base
generator is dis-
connected.
I. HORIZONTAL
MAGNIFICATION
When the
internal
time-base
voltage is
used,
the picture
can
be
magnified
in
the
horizontal direction
with
the
switch part of
the
control "X DEFL.".
When this knob
is
at the
position
"5 x iw"
(turned fully
anti
-clock-
wise), the magnification is 5 x .
When
this
knob is
turned
clockwise,
so
that
the
switch changes
over (position "CAL."),
the
magnification is
1
x .
When the knob "X DEFL."
is
at the
position "EXT." or "50 Hz", the
horizontal amplitude
can
be
regulated with the potentiometer part of the
control "X DEFL.".
J. BRIGHTNESS MODULATION
The voltage required
for
brightness modulation
should
be
connected
to the socket "Z -MOD." at the rear of the apparatus (see Fig. 1).
This
voltage
should
be approx. 30 V.
If a plug is
inserted
in the socket "Z -MOD.", the
electron
beam is sup-
pressed (and
consequently the
picture
disappears). If subsequently this
plug is
connected
to
the
chassis (socket "~"), the trace reappears.

15
K.
USE OF THE
CALIBRATING
VOLTAGE
With the aid of the
calibrating
voltage the
vertical sensitivity can
be
calibrated
as follows:
1. Set "X DEFL." to
the
position "CAL."
(turned
fully clockwise).
2. Set the "Y AMPL."
switch
to position " z ".
3.
Set
the
switch
"AC/DC"
to
the
position
"DC".
4.
Connect the socket
"CAL." to
the
input of
the
vertical
amplifier.
5. Make the
trace
visible
as described in section D2 "Time -base
inter-
nally triggered".
6. The
picture
height must now be
exactly
4 cm.
If not,
the
potentio-
meter "GAIN
ADJ."
(see Fig.
3)
must be
adjusted
until the picture
height is 4 cm.
(~ ~"~
i'~_
.
R 49
GAIN
ADJ
R 38
DC BAL
Fig. 3. View
of side controls
R13
i

17
SERVICE
DATA
Description o f
the working principle
A.
INTRODUCTION
0
The
input
signal
is
connected
via the stepped attenuator
to the vertical
amplifier,
the
output stage of which
drives the vertical
deflection plates
of
the
cathode-ray
tube. A trigger
output is fed
from
the vertical
amplifier
to the pulse
-shaper for internal triggering.
An input is also provided
for
external triggering.
The
trigger circuit produces output
pulses
which
gate the horizontal
sweep -circuit
at
the
correct
time.
The sawtooth
output
waveform of
the sweep
-circuit is amplified by
the horizontal amplifier
and
applied
to
the horizontal
deflection
plates
of the cathode-ray tube. When an
external sweep signal
is used
this is connected to
the
horizontal
amplifier
directly
via
the "X AMPL." sockets.
The
calibration voltage source provides
asquare-wave output which can
be
used
for calibration of the vertical deflection
system via the amplifier.
B.
ATTENUATOR
The
input signal is
applied
to socket "Y
AMPL."
and
thence to the
amplifier via
an
attenuator network
selected
at switch
"Y
AMPL."
(SK2).
Switch "AC/DC" (SKS)
switches the blocking
capacitor C7
in or out as
required. The attenuator consists
of fi ve sections which
provide 12 different
attenuation
positions.
Trimmers
Cl-C3-CS-C11-
C71-C72
and C74
provide frequency -independent
adjustment of the
attenuators.
C.
VERTICAL
AMPLIFIER
The
amplifier consists
of
a
phase inverter stage (B1 -B2) and
a
balanced
output stage
(B3 -B4). Switch
"NORMAL —
2 mV" changes the
cathode
resistance of
stage (B1 -B2).
When switch
"Y AMPL." is at "10
mV/cm"
and switch
"NORMAL —
2 mV"
at "NORMAL" the
sensitivity is
10
mVp_p/cm.

18
Switching to "
2 mV"
increases
the
sensitivity to 2 mV p
_ P
/cm
(in
both
cases
with continuous control
"Y AMPL."
(R7)
at
"CAL."). Potentio-
meters R38 (coarse) and R13 (fine) serve
for the balancing of the output
stages.
Potentiometer "y
YT " (R3)
provides the vertical
shift
facility
and
choice
resistor R44 provides for range of
adjustment
of R3.
Potentiometer R49 serves
for
the
adjustment of
the
sensitivity
of
the
amplifier.
D.
TRIGGER
PULSE SHAPER
This circuit consists of
acathode-coupled stage (B9 -B9') and
a
Schmitt
trigger
circuit
(B10 -B10').
Trigger
signals derived
from the
vertical
amplifier, mains
internal or
an
external source, by
selection,
are
formed
into narrow trigger
pulses
of
constant amplitude.
Switch
"TRIGG."
(SK7) serves for polarity
selection
of the trigger
signals. Internal
triggering is automatically cut off by insertion of a plug
into socket
"EXT.
TRIGG."
(BU4, SK10).
Control
"TRIGG. LEVEL"
(R9)
determines the magnitude of the d.c.
voltage
level on the grid of B9, hence the
level
of the input voltage at
which
the time
base is
triggered.
The
threshold
voltages of
the Schmitt trigger circuit are adjustable by
R137.
Because the Y amplifier is d.c.
coupled,
if the RC time of the input
circuit is large the trace may disappear for some time when control
"y YT " is
turned.
Therefore,
with internal triggering, with switch
"TRIGG" (SK7)
in positions "-~-HF" and "—HF",
a
small capacitance
C28 is
connected in series with
C26.
In the case
of
external triggering,
with positions "-~
LF" and
"—LF", the
coupling is
direct
and
in positions
"-{-HF" and "—HF" C28 remains
connected.
E.
TIME -BASE
GENERATOR
The time -base generator consists of a Schmitt trigger (B12 -B12')
(time -
base
trigger circuit),
two blocking
diodes (GR1 and
B13'
circuited
as a
diode),
aMiller-integrator (B14) (sweep circuit) and three cathode
fol-
lowers (B 11'-B 13-B 14'). It
can
function either free -running or triggered.

n
n
n
w
i
i
i
i
i
i
1
1
1
A
1
19
1.
Time -base
tr igger
circuit
The
trigger
pulses from
the
pulse shaper are
applied
to the
Schmitt
trigger (B12 -B12'),
which
switches at
a
certain level determined
by
the
setting of R159. When
this
occurs an output pulse starts the
sweep
circuit. The valves of the Schmitt trigger
are
coupled
via cathode follower
B11'
in order to
keep the
rise
time
of
the
pulses small.
The
circuit
acts as
an electronic switch
for the sweep circuit. When
the
trigger pulse is applied
the
Schmitt
circuit
switches,
diodes GR1 and
B13'
are cut
off
and
the Miller "run-down" commences.
2.
Time -base sweep circuit
The
Miller integrator (B14) provides
an
extremely linear
sawtooth
output
waveform, built up on a
timing
capacitor. The rate at which
the
charge
builds up, on this
capacitor,
determines the sweep time/cm.
The rate
of
charge is, in
turn,
dependent on the
time -constant of
the
timing capacitor
and
resistor
selected
by means of switch "/vv"
(SK8).
Feedback is applied
to the timing capacitor via cathode follower
B14' to
reduce nonlinearity in the
charging
of the
capacitor,
thus ensuring
a li near
sawtooth output waveform. The output to the
horizontal amplifier
is
taken from the junction of R171
and
R172
and
an external
output is
available at BU8.
The
sawtooth
waveform from the sweep cathode follower is applied
via
cathode follower B13 to the input of B12 for resetting the trigger
circuit
at the
end
of each sweep.
The d.c. level at the input
of B12 is controlled
by potentiometer
"TRIGG.
STAB." (R10). This can be set to permit
triggering
or
free running of
the
time
-base circuit.
R170
controls the length of the
time -base
line on the
screen.
Sweep time
selection with
switch "/w"
(SK8) provides
18
calibrated
times
which are adjustable
with
C43
and
R178 -R182. Continuous
sweep
time variation is available
at control "/W" (R12).
F. HORIZONTAL AMPLIFIER
The
amplifier consists of
acathode-coupled, push-pull
stage which
amplifies the saw
-tooth signal and controls the horizontal
deflection
plates
symmetrically. The amplification is adjustable with R98
and
horizontal shift is
effected with control "FX-~" (R2).
The
horizontal
deflection source is chosen
with
switch "X DEFL."
(SK3)
which
has three positions,
as follows: