Philips pm3232 - Page 37

79
5.2.4.2.
D.C.
Balance (R6, R7)
-
Depress
Ya
(Yb)
switch
SK4
(SK5),
+
switch
SK8
and
BEAM
SELECTOR
switch
A
SK14
(B
SKI
5)
—
Set
AC-O-DC
switch
SK16
(SK19)
to
0
—
Set
AMPL
potentiometer
R4
(R5) to
CAL
—
Check
that
the
trace
does
not
shift
if
AMPL
switch
SKI
7
(SK18)
is
switched
from
.1
V/cm to 2
mV/cm.
If
necessary,
readjust
DC
BAL
R6
(R7).
During
the
adjustment,
the
trace
must be
kept
in
the
centre
of the
screen by
means
of
POSITION
potentiometer
R11
(R12)
-
Check
that
the
position
of
the
trace
is the
same
in
positions
2,
5,
10,
20,
50
and
100
mV/cm
of
AMPL
switch
SK17
(SK18);
maximum
allowable
difference
4
mm
3.2.4.3.
Gate
current (R126,
R326)
-
Depress
Ya
IYb)
switch
SK4
(SK5),
BEAM
SELECTOR
switch
A
SK14
(B
SK15)
and
+
switch SK8
-
Set
AMPL
switch SK17
(SK18)
to
2
mV/cm
—
Check
that
the trace
does
not
jump
when
AC-O-DC
switch
SK16
(SK19)
is
switched
from
0
to
DC;
if
necessary,
readjust
potentiometer
R126
(R326);
Fig.
3.13.
tolerance at
final
check
4 mm.
3.2.4.4.
Pre-amplifier
(R64, R99,
R264, R299)
-
Depress
Ya (Yb)
switch SK4 (SK5),
AUTO
switch SK10
and
BEAM
SELECTOR
switch
A SK14 (B
SK15)
—
Set
TIME/cm
switch SK2
to
10 ms
and
TIME/cm
potentiometer
R2 to GAL
-
Set AC-O-DC
switch SK16
(SK19)
to
DC
-
Set
AMPL switch
SK17
(SK18)
to .1
V/cm
and
AMPL
potentiometer
R4 (R5)
to CAL
—
Apply
a
square-wave
voltage
of 600
mVp.p, 100
Hz, to
Ya (Yb)
input
socket
BU3
(BUS)
—
Check
that
the pulse top
is straight;
if
necessa>Y,
readjust
potentiometer
R99 (R299),
Fig. 3.13.
-
Set
AMPL
switch SK17
(SK18)
to 2
mV/cm
—
Decrease
the input
voltage to
12
mVp.p
—
Check
that the
pulse top is
straight;
if
necessary,
readjust
potentiometer
R64 (R264),
Fig.
3.14.
-
Check
that
in
the
ranges
50,
20,
10 and 5
mV/cm
of AMPL
switch
SK17
(SK18)
the
top
is straight;
tolerance 1
%
3.2.4.5.
Sensitivity
(R111, R311)
-
Depress
Ya
(Yb)
switch
SK4
(SK5),
AUTO
switch SK10,
+
switch SK8
and
BEAM
SELECTOR
switch
ASK14
(BSK15)
-
Set
TIME/cm
switch SK2
to 2
ms and
TIME/cm
potentiometer
R2 to
CAL
-
Set
AC-O-DC
switch
SK16
(SK19)
to
DC
-
Set
AMPL
switch
SK17
(SK18)
to
.1 V/cm
and
AMPL
potentiometer
R4 (R5)
to
CAL
—
Apply
a
voltage
of
exactly 600
mVp.p,
2 kHz, to
Ya
(Yb)
input
socket
BUS (BU5)
-
Check that
the trace
height is
exactly
6 cm;
if
necessary,
readjust
potentiometer
R1 1
1
(R31
1),
Fig.
3.13.
-
Check that
the
control
range of
AMPL
potentiometer
R4 (R5)
is
1 :2.6 to
1
:4
3.2.4.6. Input
attenuator
(C28,
C29, C33,
C34, C52,
C228,
C229, C233,
C234,
C235, C252)
—
Depress
Ya
(Yb)
switch SK4
(SK5), AUTO
switch
SK10,
+
switch
SK8 and
BEAM
SELECTOR
switch
ASK14
(BSK15)
-
Set
TIME/cm
switch SK2
to
50
jUs
and
TIME/cm potentiometer
R2 to CAL
-
Set
AC-O-DC
switch SK16
(SK19) to DC
—
Connect
a
square-wave voltage
with an amplitude as
indicated
in the
following table,
a repetition
rate
of
10
kHz
and a
rise time not
exceeding
200 ns
to
Ya (Yb)
input
socket BUS (BU5).