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• if the diode is o.k. the display will show “Good“
• if the diode is defective (short circuit) or low-ohmic “shrt“ (for short)
is displayed
• If the diode is defective in the sense of high-ohmic or the test leads
are confused (red to the cathode and black to the anode) “OPEn“ for
(open circuit) is displayed
5.6 Frequency Measurement
Attention!
Observe the max. input limits. Never connect voltages over 750 VDC/
VACrms (rms = eff).
It is life dangerous to touch the terminals or probe tips when measuring
voltages over 25 VAC or 35 VDC.
Disconnect the test-leads from the contact points when measuring vol-
tage (over 25 VAC or 35 VDC) before changing the meter function and
range. The sensitive electronic of the measuring unit might be destroy-
ed and you expose yourself to severe shock hazard.
Follow these steps to measure frequency:
1. Set the rotary function switch (10) to “FREQ“
2. Plug in the test-leads into the COM-socket (black = “-“) and the
V/Ohm-socket (red = “+“).
3. Connect the test-lead tips with the frequency source (generator, etc.).
Hint!
For most accurate measurements, we strongly recommend to use a BNC-
cable (Conrad Electronic offers adapter).
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1 second earlier on the main display, the middle sub-display shows the
reading which was 2 seconds earlier in the main display and the right
sub-display shows the value which was 3 seconds earlier on the main-display.
5.5 Diode Test
Set the measuring function switch (10) to “
“. The annunciator for
diodes is displayed. Manual range selection is not possible.
Now connect the test-lead tips with the object under measurement an
off-circuit semiconductor line, the RED probe-tip to the anode, the
BLACK test-lead tip to the cathode (as a rule it is marked with a colou-
red ring, point etc.)
If you check a diode’s forward voltage, you will measure voltage of
approx. 0.25 V (Germanium) or 0.7 V (Silicium), if the diode is not defective.
If you reverse the probe-tips, this means Red to the cathode and Black to
the anode, you check the so called reverse direction.
If “OL“ is displayed the diode is open or above 2.0 V forward voltage.
However, if a value between 0 V and approx. 2.0 V is displayed, it shows
a forward drop voltage.
The test voltage of the diode test is enough to “illuminate“ most (low
current) LEDs. If the LED has an operating voltage of more than 2.0 V, the
DMM displays falsely that the LED is defective.
Attention!
During diode test, observe that the diode or the circuit in which it is
built in, must be without voltage. All existing capacities must be
discharged.
Hint!
During diode test the middle sub-display is active:
