Fluke 287 Fluke 287 and 289 Multimeter Users Manual - Page 46

Testing Diodes - accuracy

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287/289 Users Manual To measure capacitance, position the rotary switch to P and set up the Meter as shown in Figure 19. If the display doesn't already indicate the Meter is measuring capacitance, press the softkey labeled Menu. Next, move the menu selector to the menu item labeled Diode,Cap and press the softkey labeled Cap. Note To improve measurement accuracy of small value capacitors, press Menu and move the menu selector to the menu item labeled REL. With the test leads open, press the softkey labeled REL to subtract the residual capacitance of the Meter and leads. Testing Diodes W Caution To avoid possible damage to the meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before testing diodes. Use the diode test to check diodes, transistors, silicon controlled rectifiers (SCRs), and other semiconductor devices. The test sends a current through a semiconductor junction, and then measures the junction's voltage drop. A typical junction drops 0.5 V to 0.8 V. To test a diode out of a circuit, position the rotary switch to P and set up the meter as shown in Figure 20. If the display doesn't already indicate the Meter is in the Diode Test function, press the softkey labeled Menu. Next, move the menu selector to the menu item labeled Diode,Cap and press the softkey labeled Diode. If the beeper is enabled during diode test, it will beep briefly for a normal junction and sound continuously for a shorted junction, below 0.1 V. See the "Disabling and Enabling the Beeper" section to disable the beeper. In a circuit, a similar diode should still indicate a forward-bias reading of 0.5 V to 0.8 V; however, the reading can vary depending on the resistance of other pathways between the probe tips. Note R and MIN MAX are disabled when the Meter is setup for diode test. 36

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287/289
Users Manual
36
To measure capacitance, position the rotary switch to
P
and set
up the Meter as shown in Figure 19. If the display doesn’t
already indicate the Meter is measuring capacitance, press the
softkey labeled
Menu
. Next, move the menu selector to the
menu item labeled
Diode,Cap
and press the softkey labeled
Cap
.
Note
To improve measurement accuracy of small value
capacitors, press
Menu
and move the menu selector
to the menu item labeled
REL
. With the test leads
open, press the softkey labeled
REL
to subtract the
residual capacitance of the Meter and leads.
Testing Diodes
W
Caution
To avoid possible damage to the meter or to the
equipment under test, disconnect circuit power
and discharge all high-voltage capacitors before
testing diodes.
Use the diode test to check diodes, transistors, silicon controlled
rectifiers (SCRs), and other semiconductor devices. The test
sends a current through a semiconductor junction, and then
measures the junction’s voltage drop. A typical junction drops
0.5 V to 0.8 V.
To test a diode out of a circuit, position the rotary switch to
P
and set up the meter as shown in Figure 20. If the display
doesn’t already indicate the Meter is in the Diode Test function,
press the softkey labeled
Menu
. Next, move the menu selector
to the menu item labeled
Diode,Cap
and press the softkey
labeled
Diode
.
If the beeper is enabled during diode test, it will beep briefly for a
normal junction and sound continuously for a shorted junction,
below 0.1 V. See the “Disabling and Enabling the Beeper”
section to disable the beeper.
In a circuit, a similar diode should still indicate a forward-bias
reading of 0.5 V to 0.8 V; however, the reading can vary
depending on the resistance of other pathways between the
probe tips.
Note
R
and MIN MAX are disabled when the Meter is
setup for diode test.