Conrad MXD 4660 A Bedienungsanleitung Seite 10

red black
measuring measuring
Conducting direction
Next, connect the measuring probes to the object under test, a non-live semicon-
ductor path, with the red measuring probe at the anode, and the black measuring
lead to the cathode (normally identified by a colored ring, point or similar).If you
check a diode path in the conducting direction, you will measure a voltage of bet-
ween approx. 0.6 V (silicon) to 2.8 V (or 600 mV to 2800 mV), assuming that the diode
is not faulty. Also, in the middle subdisplay you can see "good", i.e. OK.
You can test the so-called off-state of the diode path by now reversing the measuring
leads, i.e. red to the cathode and black to the anode.
The diode is OK when you obtain a bar graph flashing "OL" (for overload), and in the
middle subdisplay "OPEN" appears. However, if a voltage value is displayed, either
the object under test is defect or incorrectly connected.
Important!
When testing diodes, make absolutely sure that the diode, or the
circuit of which it is part, are not live. Any capacitors must be
discharged.
With germanium or selenite diodes/semiconductors, the middle
subdisplay shows "bAd" (bad, faulty) instead of "good" (OK).
E Transistor test
Important!
The transistor header socket is not protected against overload.
How to measure the amplification of a transistor:
1. In the button cluster "FUNCTION", press button "hFE".
2. Insert the transistor to be checked into the measurement socket. Take special
care with the following:
• Make sure the connection sequence (e.g. C-B-E) of the object under test is cor-
rect (refer the transistor comparison table/list).
• Some types of transistor include base-to-emitter resistances. This can falsify
measurements.
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black
red
measurin measuring
Blocking direction
• The hFE measurement value is not absolutely accurate, and only tells you
whether the transistor is working or not. The actual amplification of a transistor
depends on its operating current. Your Multimeter can supply a base current of
up to 1000 A at a Vce of 2.8 V. The collector current flowing during the measu-
rement is measured and the hFE value calculated from it.
• You are not able to measure transistors which are built into a circuit.
• With this Multimeter, it is not possible to measure hFE values for FETs or other
unipolar transistors.
• f the connecting pins of the object under test do not fit into the socket (too large),
do not employ force (which could damage the socket).
• The hFE measurement is sensitive to temperature fluctuations. The measurement
value can change as soon as you touch the sensor and connect it to the socket
(warmth of the fingers). If you obtain a display which does not stabilize, remove
the transistor and allow it to cool to room temperature.
During the measurement of the transistor parameter hFE, the three subdisplays to
the right of the display are also active. The upper subdisplay displays the current
measurement value with a 1 s delay. The middle display shows the measurement
value with a 2 s delay. The lower subdisplay shows the measurement value with a 3
s delay.
F Measuring frequency
When measuring frequency it is not possible to set the measuring ranges manually.
Switchover is automatic.
This is how to measure a frequency:
1. Connect the black measuring lead to the COM socket, and the red measuring
lead to the V/Ohm socket.
2. In the button cluster "FUNCTION", press the "FREQ" button and connect the
measuring probes to the object under test (generator, etc.).
Important!
Make sure that the max. input parameters are not exceeded!
Connect no voltages greater than 250 VDC max. (or VACrms). Tou-
ching voltages greater than 25 VAC (or 35 VDC) constitutes a
potentially lethal hazard.
During measurements, do not switch to a different measurement
function. This could irreparably damage the sensitive electronics
in the interior of the measuring device, and is a potential hazard
for the user.
It is not possible to measure frequency at voltages smaller than
approx. 50 mVrms (measured at 1 kHz) .
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