Operating Information—2445 Service
(21) CALIBRATO R Connector—Provides a 0.4-V p-p
square-wave signal into a 1-M£2 load, a 0.2-V p-p
square-wave signal into a 5(M7 dc-coupled load, or
an 8-mA p-p square-wave current signal into a short
circuit at a sweep speed o f 1 ms per division. The
CALIBRATOR output signal is useful fo r checking
the sweep, the delays, and the vertical deflection
accuracies, as well as compensating voltage probes
and checking the accuracy o f current probes. The
repetition rate o f the square wave changes w ith the
setting of the A SEC/DIV switch. For all sweep-speed
settings from 100 ms per division to 100 ns per
division, the A Sweep display, as seen on the instru
ment supplying the CALIBRATOR signal, w ill be
five cycles per 10 divisions. A t 100 ms per division
and slower, the CALIBRATOR frequency w ill be
5 Hz; at 100 ns per division and faster, the frequency
w ill be 5 MHz. The signal amplitude at 5 MHz w ill be
at least 50% o f the signal amplitude obtained when
the sweep speed is set to 1 ms per division.
NOTE
Due to internal circuitry constraints, the
calibrator signal is not synchronized during
trace holdoff. This does not affect the accuracy
o f the calibrator signal that is present during
a trace display. However, i f the 2445 C ALI
BRATOR signal is used to calibrate other
instruments, the sweep o f the 2445 must be
shut off. i f it is not, the signal w ill appear to
jitte r and w ill give false (low) frequency counts
The sweep o f the 2445 is easily shut o f f by set
ting the TRIGGER MODE switch to SGL SEQ.
(22) Auxiliary Ground Jack—Provides an auxiliary signal
ground when interconnecting equipment under test
and the oscilloscope. Hookup is made via a banana-tip
connector.
HORIZONTAL AND
DELTA MEASUREMENT
Refer to Figure 2-5 for location of items 23 through 33.
(23) A SEC/DIV Switch—Selects 25 calibrated A Sweep
speeds from 1 s per division to 10 ns per division, or
delay ranges from 10 s to 200 ns, in a 1-2-5 sequence.
Extreme counterclockwise switch rotation selects the
X-Y display mode. In X-Y, the signal applied to the
CH 1 OR X input connector drives the horizontal
deflection system.
(24) B SEC/DIV Switch—Selects 21 calibrated B Sweep
speeds from 50 ms per division to 10 ns per division
in a 1-2-5 sequence. This switch also controls Hori
zontal Display Mode switching, as explained in the
following descriptions.
Knobs Locked—When both the A SEC/DIV and
B SEC/DIV switches are set to the same sweep
speed and the B SEC/DIV knob is pushed in, the
tw o knobs are locked together; in this position,
only the A Sweep is displayed on the crt.
PULL-1NTEN—Pulling the B SEC/DIV knob to the
out position intensifies the A Sweep display fo r
the duration o f the B Sweep time. When both the
A SEC/DIV and B SEC/DIV switches are set to the
same sweep speed, the B Sweep is not displayed,
but it runs at one o f two speeds: either 100 times
faster than the A Sweep speed or at 5 ns per
division, whichever is slower. The A and B SEC/
D IV knobs are interlocked to prevent the B SEC/
D IV switch from ever being set to a slower sweep
speed than the A SEC/DIV switch setting.
The position of the intensified zone on the A
Sweep indicates the delay time between the start
of the A Sweep and start o f the B Sweep interval.
Its position is controlled by the A REF OR DLY
POS control.
For single-trace displays, when either the Delta
Time (At) or the reciprocal Delta Time {1 /A t)
function is activated, tw o intensified zones w ill
2-7
Содержание 2445
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Страница 11: ...2445 Service 3829 01 The 2445 Oscilloscope ...
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Страница 309: ...FRONT PANEL TROUBLESHOOTING ...
Страница 310: ...FRONT PANEL TROUBLESHOOTING ...
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Страница 316: ...R E TU R N T O v 1 y ...
Страница 317: ...SWEEP TROUBLESHOOTING PROCEDURE ...
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Страница 326: ... KERNEL NOP DIAGNOSTIC PROCEDURE ...
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