Fluke 189 user manual Testing for Continuity, Automatically subtract this value

Model 187 & 189

Users Manual

Keep the following in mind when measuring resistance:

•Because the meter’s test current flows through all possible paths between the probe tips, the measured value of a resistor in a circuit is often different from the resistor’s rated value.

•	The test leads can add 0.1 Ω to 0.2 Ω of error to
	resistance measurements. To test the leads, touch
	the probe tips together and read the resistance of the
	leads. If necessary, you can press D to
	automatically subtract this value.

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 30 MΩ or 500 MΩ ranges for in-circuit resistance measurements.

Testing for Continuity

Caution

To avoid possible damage to the meter or to the equipment under test, disconnect circuit power and discharge all high-voltage capacitors before testing for continuity.

Continuity is the presence of a complete path for current flow. The continuity test features a beeper that sounds if a circuit is complete. The beeper allows you to perform quick continuity tests without having to watch the display.

The continuity function detects intermittent opens and shorts lasting as little as 1 millisecond (0.001 second). These brief contacts cause the meter to emit a short beep.

To select continuity, turn the rotary switch to resistance position, then press the blue button once. The continuity symbol (~) appears in the display. Continuity uses manual ranging only; autoranging is not available. Refer to Figure 3-6 for continuity testing setup instructions.

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