Upon entenng CAL
01,
the Input Coupling is
automatically set to 50
(} DC and the
5fJ-(J
OVER-
LOAD protection is disabled. Before starting the
procedure, make sure any
50-0 OVERLOAD condi-
tion has been cleared.
In
this procedure, pressing the upper TRIGGER
COUPLING switch stores the
cu"ent
calibration
parameter being set and increments the routine to
the
next
step (except where otherwise noted).
d.
Connect the DMM, set
to
measure approximately
500
mv,
to
the CALIBRATOR output.
e.
Press
and
release the upper
TRIGGER
COUPLING
switch.
NOTE
The
CAL/BRA
TOR
output will go to its LO level on
odd CAL steps and to its HI level on even steps.
f.
CHECK-Readout indicates ADJUST t. (step)
0,
CH
1 PROBE
TO
FRONT SIDE
OF
R489.
g.
Connect a P6136 probe from
CH
1 to the front side
of
R489,
at rear
of
main board near readout connector.
h.
ADJUST
-t.
REF
to center signal
on
displayed cur-
sors,
and
ADJUST
-t.
control to join traces.
i.
Press
and
release the upper
TRIGGER
COUPLING
switch.
j. CHECK-CALIBRATOR output voltage
is
O
mV
±1
mv.
k.
Disconnect the
X10
probe.
I.
CHECK-Readout indicates ADJUST t. (step)
1,
100
µs
(for A Sweep),
and
1
µS
(for B Sweep).
Adjustment Procedure-2445A/2455A Service
NOTE
The
readout prompts the operator
by
showing the
control to
be moved (upper left corner), the autocal
step number (upper right corner), the A-Sweep
speed (bottom right center),
and
the B-Sweep speed
(bottom right comer)
as
set up
by
the routine.
An
example (from step g above) is:
ADJ
.:1
1
100µ5
1
µS
m.
Connect the Time-Mark Generator, set for 0.1-ms
time markers, to the
CH
1
OR
X input connector via a
50-0
BNC
cable.
n.
Set:
VOLTS DIV
TRACE
SEP
CH
1 POSITION
Horizontal POSITION
As
needed
for a
convenient signal
display amplitude
As
needed
to
separate the
A
and
B Sweeps
As
needed
to
view both
A
and
B Sweeps
Position start of
trace at the
left graticule line
NOTE
Some sequential pairs
of
steps are iterative, i.e.,
the earlier step is recalled
if
an adjustment is
made in the later step. Occasionally, on the earlier
of
some
of
these pairs, the readout may indicate
"LIMIT" before the correct control setting is
reached.
If
this occurs, proceed to the
next
AUTOMATIC CAL step.
After
the adjustment
at
the
next
step is performed, the previous step will
automatically
be recalled, and the adjustment may
be performed in the normal manner.
o.
ADJUST
-t.
REF
OR
DLY
POS
and
t. controls to
align both the intensified zones with the 6th time marker
(near graticule center)
and
to superimpose the delayed B-
Sweep time markers. Press and release the upper
TRIGGER
COUPLING switch.
p.
CHECK-CALIBRATOR output voltage
is
between
398
mV
and
402
mV
of the reading noted
in
part j. Discon-
nect the DMM
when
through.
5-11
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