PDi DM68 - Resistance Measurement

To measure ac or dc voltage:
1. Set rotary switch to the DCV or ACV range.
2. Connect the black and red test leads to the COM and
V terminals respectively.
3. Connect the test leads to the circuit being measured
4. Read the displayed value. The polarity of red test lead
connection will be indicated when making a DCV
measurement.
NOTE:
Unstable display may occur especially at 400mV range,
even though you do not put test leads into input terminals,
in this case, if an erroneous reading is suspected, short
the V terminal and the COM terminal, and make sure the
zero display.
. For better accuracy when measuring the dc offset of an
ac voltage, measure the ac voltage first. Note the ac
voltage range, then manually select a dc voltage range
equal to or higher than the ac range. This improves the
accuracy of the dc measurement by ensuring that the
input protection circuits are not activated.
3.2.2 Resistance measurement
I A To avoid electrical shock andlor damage to the I
I
Instrument, disconnect circuit power and
discharge all high-voltage
capacitors before
I measuring resistance.
The unit of resistance is the ohm (R). The Meter measures
resistance by sending a small current through the circuit.
Because this current flows through all possible paths
between the probes, an in-circuit resistance reading
represents the total resistance of all paths between the
The Meter's resistance ranges are
400.0R, 4.000kR,
40.00kR, 400.0kR, 4.000MR and 40.00MR.
To measure resistance:
1. Set the rotary switch to
range.
2. Connect the black and red test leads to the COM and
R terminals respectively.
3. Connect the test leads to the circuit being measured
and read the displayed value.
-
I
Some tips for measuring resistance:
The measured value of a resistor in a circuit is often
diierent from the resistor's rated value. This is because
the Meter's test current flows through all possible paths
between the probe tips.
In order to ensure the best accuracy in measurement of low
resistance, short the test leads before measurement and
memory the test probe resistance in mind. This necessary to
subtract for the resistance of the test leads.
The resistance function can produce enough voltage to
forward-bias silicon diode or transistor junctions, causing
them to conduct. To avoid this, do not use the 40MR range
for in-circuit resistance measurements.
'.
On 40MR range, the meter may take a few seconds to
stabilize reading. This is normal for high resistance
measuring.
•
When the input is not connected, i.e. at open circuit, the
figure "OL" will be displayed for the overrange condition.
probes.
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