Fluke 8050A - 2-68. Diode Leakage Tests; 2-70. Transistor Testing Procedures

2-68.
DIODE LEAKAGE
TESTS
2-69.
Diode leakage
(IR)
tests require that the diode
junction be reverse biased while being measured. Connect
the anode of the diode to the
COMMON input connector
to reverse bias a diode junction. A good silicon diode
will
produce an in-scale display reading on the
200
nS
range
when reverse biased.
2-
70.
TRANSISTOR TESTER
2-71.
The transistor tester described in the following
paragraphs provides approximate test information. Beta
is
tested using a V
CE
of
2V
and an
le
of about
200
µA.
This transistor tester
is
useful for checking the proper
operation of transistors and approximate beta values for
comparative measurements.
2-72.
The transistor tester fixture
is
described in Figure
2-12.
When assembled and connected to the
V/kO/S
and
the
COMMON
input connector, the
8050A
can be used to
determine the following information about transistors:
•
Transistor type
(NPN
or
PNP)
SCHEMATIC
•
OPERATION
CONDUCTANCE MEASUREMENT
Defective transistors (shorted or open)
•
Collector-to-emitter leakage
(lcEs)
•
Beta from
IO
to
1000
in a single range.
2-73.
Transistor type
is
determined by setting the switch
on the tester fixture to BET
A,
setting the
8050A
to the 2
mS
range, and observing the display reading.
If
a low
reading(<
0.0100)
is
displayed, reverse the test fixture at
the input connectors.
If
the collector of the transistor
is
now connected to the
COMMON
input connector the
transistor
is
a
PNP
type.
An
NPN
type will have its
collector connected to the V
/
kO
/
S
input connector.
2-74. Defective Transistors
2-75.
If
the transistor
is
defective, the following
indications will appear, regardless
of
transistor type or
test position:
I.
An open transistor will produce a display
reading
of
0.0005
or less.
TRANSISTOR
UNDER TEST TEST FIXTURE
CONSTRUCTION
DETAIL
I
1----1
7/8"---~
z
Q..
z
o.
75"
3/16"
HOLE
CB
:)J-~1~~~-----.-B-ET:A=~~-----~-'VV\.-R-l==~~~r
......
~-+:L~~INTO
~
;50k.Q
COMMON
AND
.,
Sl
V/K.Q/nS INPUT
E
>~~~~~-1c_:s--i_s
____
~~~~~-----t:PERMINALS
WIRE TO
BASE
CONTACT
OF
TRANSISTOR SOCKET
Pl
BANANA
PLUG
CON
NE
CT
OR
0.
75"
SPACING
GENERAL
RADIO
TYPE
274
MB
Figure
2·12.
Transistor Beta Test Fixture
WIRE TO
SWITCH
ARM
2-15