Adjustment Procedure-2445A/2455A Service
d.
Connect the high-amplitude output of the Calibration
Generator to the
CH
1
OR
X input connector via a 50-0
BNC
cable, a Tunnel Diode Pulser,
and
a
5X
attenuator.
e.
Set the generator Period switch to
100
kHz,
and
set
the generator amplitude control to maximum.
f.
Rotate the pulser Trigger control
CW
(from a fully
CCW position) until a stable signal first appears
on
the
graticule. Display amplitude
will
be approximately 5 divi-
sions.
The
oscilloscope TRIGGER LEVEL control
may
need
to
be
adjusted to obtain a stable display.
NOTE
As a guide
when
performing
the
following adjust-
ments, optimum performance is achieved
when
the
CH
1 and
CH
2 step response abe"ations are
~
4%
when
using
10
mV/division deflection
factors(~
0.2
division on a 5-division
signal).
g.
Preset Trans
Resp
adjustments:
NOTE
Presetting the adjustments
is
not necessary unless
vertical system components have been
replaced.
1.
Center CRT Termination (R1501).
2.
Center Trans
Resp
adjustments R403,
R605,
and
C601.
3.
ADJUST
-Trans
Resp
adjustment C404 for
maximum positive movement of the front corner
of the waveform.
4.
Set Trans
Resp
adjustment
R410
1/3
CCW from
CW
end.
5.
On
2455A instruments, ADJUST
-HF.
Adjust
(R417)
full CW
and
then CCW until the adjust-
ment slot runs front to back (approximately 90%
CCW).
h.
Press
and
release the upper
TRIGGER
COUPLING
switch.
5-18
i.
CHECK-Readout indicates ADJ
.:1
(step)
2,
10
mV.
j. ADJUST
-C403
for best corner over first ½ division
(5
ns).
k.
ADJUST - Trans Resp Adjustments C403,
R410
for
flattest corner over first 5 ns.
I.
Turn A SEC/DIV
VAR
control CCW
and
ADJUST
CRT termination (R1501) for flattest waveform.
m.
Adjust
.:1
for the flattest waveform. Set SEC/DIV
VAR for best viewing. The total system will tune up best if
the indicator cursor
is
in
the 7th or 8th divisions.
n.
Press
and
release the lower TRIGGER COUPLING
switch to return to Step 1 of CAL 06.
o.
CHECK-Readout indicates ADJ
.:1
(step)
1,
10
mV,
100
ns.
p.
ADJUST - Trans Resp adjustments (R605,
R403,
C404,
and
C601) for the flattest response
in
the first
100
ns.
q.
Disconnect the Calibration Generator
and
connect
the Primary Leveled Sine-Wave Generator
to
the
CH
1
input via a
50-0 BNC cable.
r.
Set the generator for a 6-division display at 1 MHz.
s.
Change the generator output frequency to 150 MHz
for the 2445A or to 250 MHz for the 2455A.
t.
CHECK-Display amplitude
is
between 4.4 divisions
and
6 divisions while the generator frequency
is
changed
from 100 MHz to
150
MHz for the 2445A or from
150
MHz to 250 MHz for the 2455A. This bandwidth pro-
vides optimum performance
of
the Vertical system.
u.
CHECK-Display amplitude does not drop below 4.4
divisions
when
sweeping the generator frequency from
150
MHz to 100 MHz for the 2445A or from 250 MHz to
150 MHz for the 2455A.
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