Fluke 187 user manual Testing Diodes, Capacitance Measurement

Making Measurements

Testing Diodes 3

	189 LOGGING MULTIMETER
AutoHOLD	FAST MN MX		LOGGING	YES
HOLD	MIN MAX		REL
	CANCEL		SAVE	NO
	Hz % ms		RANGE
SETUP	nS
ac+dc mV				F
			C
ac+dc V				A
				mA
dB mV				A
dB V				A
				mA
				ac+dc
OFF				A
				ac+dc
			VIEW
			CLEAR MEM
				TEMPERATURE
A	mA		COM	V
	A
10A MAX		400mA		CAT
FUSED
		FUSED		1000V
				+
				+
				+
				+
				+
				+
				+
				+
				+
				ach005f.eps

Figure 3-8. Capacitance Measurement

Testing Diodes

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 diodes.

Use the diode test to check diodes, transistors, silicon controlled rectifiers (SCRs), and other semiconductor devices. The test sends a current through a semiconductor junction, then measures the junction’s voltage drop. A typical junction drops 0.5 V to 0.8 V. In diode test, the beeper is active. It beeps briefly for a normal junction and is on continuously if a short is detected.

To test a diode out of a circuit, set up the meter as shown in Figure 3-9.

In a circuit, a similar diode should still indicate a forward- bias reading of 0.5 V to 0.8 V; however, the reverse-bias reading can vary depending on the resistance of other pathways between the probe tips.

The blue key toggles between diode test and capacitance. Since diode test uses a fixed range, R cannot be used.

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