HP 4262A User Manual

Model 4262A
Section VIII
Figure 8-11
SELF TEST FUNCTION
Pressing the SELF TEST button (located at left in line with the CIRCUIT MODE selection
buttons) directs the instrument to begin a sequence of instrument operated self-test
functions. This is an outline of how to use the self test function for failure diagnosis.
Automatic self test settings:
An appropriate equivalent circuit mode (either to SER or PRL) is automatically selected for
the duration of the self test. Since self testing is done in a particular equivalent circuit mode
for each of the measurement parameters (L, C and R), auto testing is limited to the ranges
specified for these circuit modes. The table below shows measurement ranges tested by self-
test function. However, since, during self test, all instrument measurement functions are
brought into action (including all the range resistors), this test is broad check of overall
instrument performance for all ranges.
Table 8-5. Self Test Ranges.
Range Cs m Ls ~“T0W\ Rs m
1 100pF 100uH 1000m&2
2 1000pF 1000uH 100
3 10nF 10mH 1009
4 100nF 100mH 100082
5 1000nF 1000mH 10kQ
Note
Multiply range by 10 at 120Hz and by 0.1 at
10kHz test signal frequencies.
How the self test function operates:
To perform the self test, the instrument simulates a measurement of either zero or infinite
impedance. For these tests, the UKNOWN terminals are appropriately terminated (short or
open). Under these test conditions, the integrator develops an output voltage correspond-
ing to a2 1000 count display (full scale) for the LCR measurement test cycle and a 000 count
display for the DQ measurement test cycle. The nanoprocessor monitors the 1000 and 000
counts calculated from the integrator output. If either or both of the counted numbers
differ by more than 5 counts from their respective nominal values, a FAIL annunciation is
displayed on the LCR DISPLAY. The nanoprocessor also monitors a SAT signal from
Saturation Detector (A13) to further categorize the failures into other subdivisions.
Figure 8-11. Self Test Function (sheet 1 of 2).
8-21

HP 4262A Specifications

General

Brand	HP
Model	4262A
Category	Measuring Instruments
Language	English