6-1
The EXT CAL routines also provide the automatic
REPET calibration and the display Signals for the manual
ADJUSTS needed for the Display System and CCD output
amplifier calibrations. REPET calibration adjusts the timing
of the jitter correction ramps. The jitter correction ramps
are used measure the time between the randomly acquired
Extended Calibration
Semiautomatic calibration of the vertical attenuators
(ATTEN) and external trigger amplifiers (TRIGGER) is sup-
ported by this level of calibration. The technician must sup-
ply the dc voltage levels required for calibration to the
input connectors, and the scope then performs the actual
calibration of the gain of the vertical input attenuators and
gain and offset of the external trigger amplifier using the
supplied de voltages. During the ATTEN calibration, the
accuracy of the internal 10
V
Calibration Reference is
verified against the standard amplitude VOltageapplied to
the attenuators.
Maximum instrument accuracy can be assured by doing
a SELF CAL just before making critical measurements.
Continued accuracy is maintained by running SELF CAL
whenever the operating temperature has changed more
than five degrees Celsius since the last SELF CAL.
Self Calibration
Almost all of the measurement systems within the 2430
are calibrated with the SELF CAL procedure. These
automatic adjustments include the gain and offset settings
for the vertical acquisition system and the internal trigger
system. No adjustments are required for the time base or
horizontal subsystems.
Calibration Levels
Calibration of the 2430 occurs at several levels. These
levels are the fully automatic SELF CAL, the semi-
automatic EXTENDED CAL, the manual adjustments, and
dynamic calibration.
Adjustments that remain for the display system and
CCD output amplifiers and those requiring external stand-
ard test signals are not automatic, but they are aided by
the built-in programming. The 2430 supplies the test sig-
nals for the display system and CCD output amplifier
adjustments and does the actual calibration of the vertical
attenuators and trigger amplifiers once the standard volt-
age calibration signals are provided.
Instead of the usual numerous manual potentiometer
"tweeks" that require extensive servicing, the 2430 makes
wide use of digital calibration techniques. The extensive
digital-to-analog (DAC) subsystem of the scope and the
built-in computer firmware are used to calculate and adjust
more than 100 voltages that control gain, offset, and other
parameters of circuit operation affecting accuracy. The
automatic SELF CAL uses no external test equipment and
takes less than 10 seconds to complete. The ease of use
of SELF CAL allows it to be done at any time to assure
the user of an accurate measurement in the present test-
ing environment.
The 2430 Digital Oscilloscope is designed to provide as
near total automatic calibration as practical. Automatic
procedures minimize manufacturing and end-user costs
associated with calibration and enhance the accuracy of
the instrument during use.
CALIBRATION IN THE 2430
DIGITAL OSCILLOSCOPE
This section contains useful information on the calibra-
tion of the 2430 and for conducting preventive mainte-
nance, troubleshooting, and corrective maintenance on the
2430 Oscilloscope. Circuit board removal procedures are
included in the "Corrective Maintenance" subsection. An
extensive diagnostic procedures table (Table 6-6) is pro-
vided in the "Diagnostics" subsection at the back of this
section.
MAINTENANCE
Section 6-2430 Service
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