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c)
Resistance measurement “Ω”
Make sure that all the circuit parts, switches and components and other objects of measurement
are disconnected from the voltage and discharged.
1
Proceed as follows to measure the resistance:
-
Turn the DMM on and select measuring range “Ω”.
-
Plug the red measuring lead into the Ω measuring socket (8) and the black
measuring lead into the COM measuring socket (7).
- Check the measuring leads for continuity by connecting both measuring
prods with one another. After that the resistance value must be approximately
0 to 0.5 Ohm (inherent resistance of the measuring leads).
- Connect the two measuring prods to the object to be measured. As long as
the object to be measured is not high-resistive or interrupted, the measured
value will be indicated on the display. Wait until the display has stabilised.
With resistances of >1 MOhm, this may take a few seconds.
- As soon as „OL“ (overload) appears on the display, you have exceeded the measuring range or the measuring
circuit has been broken.
- After measuring, remove the measuring leads from the measuring object and turn the DMM off.
If you carry out a resistance measurement, make sure that the measuring points which you contact with the
test prods are free from dirt, oil, solderable lacquer or the like. An incorrect measurement may result under
such circumstances.
d) Diode test
Make sure that all the circuit parts, switches and components and other objects of measurement
are disconnected from the voltage and discharged.
- Turn the DMM on and select measuring range
- The diode symbol appears on the display.
-
Plug the red measuring lead into the Ω measuring socket (8) and the black
measuring lead into the COM measuring socket (7).
- Check the measuring leads for continuity by connecting both measuring
prods with one another. After that the value must be approximately 0 V.
- Now connect the two measuring prods with the object to be measured (di-
ode).
- The display shows the continuity voltage „UF“ in volt (V). If „OL“ is indicated,
the diode is measured in reverse direction (UR) or the diode is defect (inter-
ruption). Perform a counter-pole measuring for control reasons.
- After measuring, remove the measuring leads from the measuring object and
turn the DMM off.
Silicone diodes have an on-state voltage (UF) of approx. 0.4 – 0.9 V.
