KYORITSU 1109S User Manual

Page 28

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̶ 26 ̶

As indicated in Fig. 9, connect the h

FE

test lead (1) to the multimeter,

according to the polarity of a transistor to be tested; N (-COM) terminal

for the NPN type transistor or P (+) terminal for the PNP type transistor.

Also, connect the h

FE

test lead (2) to the P(+) terminal for the NPN type

transistor and the N (−COM) terminal for the PNP type transistor. With

the test lead clips (E) and (C) shorted, turn the ohm zero adjust knob so

that the pointer lines up with the zero (0) mark on the right end of the

ohm scale. Then, connect the h

FE

test lead clips as follows:

Clip (C) and clip (B) for h

FE

test lead (1) to the collector and base

terminals of the transistor respectively.

Clip (E) of the h

FE

test lead (2) to the emitter of the transistor.

⑶ When the transistor is good, the indicated value is small,

representing leakage current I

CEO

only with the base terminal open

(l

B

=0).

If base-terminal DC current I

B

flows, collector-terminal DC current I

C

changes and meter gives a reading of the current increased by I

B

X

h

FE

.

⑷ When the transistor is faulty, the three possible cases may be

considered.

There is no change in the current reading between the times when

the base terminal is open (l

B

=0) and when I

B

flows.

No meter pointer deflection even when I

B

flows.

The meter pointer moves past the h

FE

scale and deflects close to full

scale, even when the base terminal is open (I

B

=0).

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