Extech Instruments CT40 User's Guide download pdf (Page 6)

CT40- EU-EN V1.7 1/13

Continuity Check

WARNING: To avoid electric shock, never measure continuity on circuits or wires that have

voltage on them.

1. Set the function switch to the position.

2. Insert the black lead banana plug into the negative (-) jack (COM) and the red test lead banana

plug into the positive (+) jack ().

3. Press the MODE button until the symbol appears in the display.

4. Touch the test probe tips to the circuit or wire you wish to check.

5. If the resistance is less than the continuity threshold, the audible signal will sound. The display

will also show the actual resistance.

DIODE TEST

WARNING: To avoid electric shock, do not test any diode that has voltage on it.

1. Set the function switch to position.

2. Press the MODE button until the symbol appears in the display.

3. Insert the black test lead banana plug into the negative (-) jack (COM) and the red test lead

banana plug into the positive (+) jack ().

4. Touch the test probe tips to the diode or semiconductor junction you wish to test. Note the

meter reading.

5. Reverse the probe polarity by switching probe position. Note this reading.

6. The diode or junction can be evaluated as follows:

A. If one reading shows a value and the other reading shows OL, the diode is good.

B. If both readings show OL, the device is open.

C. If both readings are very small or 0, the device is shorted.

NOTE: The value indicated in the display during the diode check is the forward voltage.

MAX Hold Function

1. Press the MAX Hold Button. The meter continues taking measurements but the display shows

only the highest (MAX) reading recorded.

2. Press the Max Hold Button again to return to normal operation.

Data Hold Function

1. Press the Data Hold Button. The HOLD indicator will appear. The hold function freezes the

reading in the display.

2. Press the Data Hold Button again to return to normal operation.

Auto Power OFF Function

The auto off feature will turn the meter off after 15 minutes.

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Extech Instruments CT40 User's Guide Page 6