Adjustment Procedure-2445A/2455A Service
d.
Rotate the
~
control
CW
until the DMM reading
remains at a constant value (approximately
+ 1.250
V).
Note the reading.
e.
Add
the absolute values of the readings noted
in
parts c
and
d together (approximately 2.500
V).
f.
Subtract the total
in
part e from 2.500
V,
then divide
the difference by two.
g.
ADJUST-DAC
Ref (R2010
on
the Control Board) to
add the (signed) number obtained
in
part f to the reading
obtained
in
part
d.
h.
Repeat parts c through g
as
necessary to obtain a
total
DAC
range of 2.500
V.
i.
Disconnect the DMM.
2.
Adjust
CH
1 and
CH
2 Input Capacitance (C105
and C205).
NOTE
If
the previous step was not performed, first set up
the Initial Control Settings before the DAC Ref
adjustment, then proceed as follows.
NOTE
The
objective
of
this adjustment
is
to match the
input capacitance
of
the 50-mV-per-division position
of
the VOLTS/DIV switches to
the
100-mV-per-
division position.
The
front corner
of
an input
square-wave signal is used to indicate when the
capacitances are matched.
a.
Connect a 1-kHz square-wave signal from the Cali-
bration Generator high-amplitude output to the
CH
1
OR
X
input connector via a
50-U
BNC
cable, a 50-0 termination,
and
a normalizer. Adjust the generator output
level
for a
6-clivision signal vertically centered
on
the graticule.
b.
Set
the normalizer for a square front corner over
approximately the first 40
µs
(0.4 division) of the positive
portion of the waveform.
c.
Change
the
CH
1 VOL TS/DIV switch to the 50-mV
position
and
adjust the generator for a 6-clivision signal
display.
5-8
d.
ADJUST-The
CH
1 50-mV C Adj (C105
on
the
Main Board) for the same waveform front corner noted
in
part
b.
e.
Repeat parts b through d until no change
is
observed
in
the waveform front corner when the
CH
1 VOL TS/DIV
switch
is
alternated between the 50-mV
and
100-V posi-
tions.
When
switching between positions, reestablish the
reference display amplitude at
each
position, and observe
the square-wave front corner to make the comparison.
f.
Move the input signal
to
CH
2
and
change the VERT-
ICAL MODE to display
CH
2 only. Adjust the generator
amplitude for a 6-clivision signal amplitude.
g.
Set the normalizer for a square front corner over
approximately the first 40
µS
(0.4 division) of the positive
portion of the waveform.
h.
Change the
CH
2 VOL TS/DIV switch to the 50-mV
position
and
adjust the generator for a 6-clivision display.
i.
ADJUST -
The
CH
2 50-mV C Adj (C205
on
the Main
Board) for the same waveform front corner noted
in
part
g.
j. Repeat parts g through i until no change
is
observed
in
the waveform front corner
when
the
CH
2 VOL TS/DIV
switch
is
alternated between the 50-mV
and
100-V posi-
tions.
When
switching between positions, reestablish the
reference signal amplitude at
each
position, and observe
the square-wave front corner
to
make the comparison.
k.
Disconnect the test setup.
3.
Adjust Vertical Readout Jitter (R618).
NOTE
If
the previous step was
not
performed, first set up
the Initial Control Settings before
the
DAC Ref
adjustment, then proceed as follows.
a.
Set the VERTICAL MODE to display
CH
1 only. Set
the
CH
1 Input Coupling to 50 0
DC.
Set the A SEC/DIV
to 500
µS.
b.
Press
and
release the ~V button to obtain a ~V
display.
To Next Page
Loading...
