TM 11-6625-539-14-4
necessary, using the METER ZERO control. Re-
(6) Operate the POLARITY switch to EB
lease the toggle switch so that it returns to the
position.
ZERO position and zero the meter using the ICES
(7) Adjust ICES ZERO/OHMS ADJ COARSE
ZERO/OHMS ADJ FINE control.
and FINE controls to indicate infinite reading on
(7) Connect the test leads to the color-matched
OHMS scale of meter. Short together the E-B
remote test jacks. Connect the red lead to the
jacks. Zero the meter using the METER ZERO
collector, the black lead to the base, and the
control. Remove the short and readjust as neces-
yellow lead to the emitter of the device under test.
sary for an infinite reading. Repeat the procedure
as required until zero and infinity are properly
(8) Use the ICES ZERO/OHMS ADJ COARSE
set.
and FINE controls to zero the meter. This will
null the effects of the circuit loading.
(8) Insert the test leads into the panel test
jacks, being sure to match lead and jack color.
(9) Press and hold the ICES toggle switch to
Connect the red lead to the collector, the black
READ and check the indication on the meter. Mul-
lead to the base, and the yellow lead to the
tiply the reading by the setting of the RANGE
emitter of the device under test.
switch. This is the ICES value. Compare this value
(9) Sequentially operate the POLARITY
with that in section II of appendix D. Reject the
transistor if leakage is greater than that listed.
switch from EB to CB to E-C, checking the
(10) Disconnect the test leads from the device
meter deflection at each position on the OHMS
under test. Turn the POLARITY SWTICH TO
scale. These positions indicate resistive load
OFF.
across each portion of the transistor circuit. Re-
sistance across any portion of the circuit shall not
be less than 500 ohms. If resistance is less, a
Transistors (FET's)
significant beta reading cannot be made in circuit.
(10) If resistance is greater than 500 ohms at
FET devices are tested for transconductance and
all positions, restore the FUNCTION switch to
the values are given in micromhos (microsiemens)
BETA. Read the value on the BETA scale of the
on the GM scale. Test out of circuit as follows:
meter. If necessary, adjust the RANGE switch to
a. Operate the POLARITY switch to PNP for P-
X 10 and multiply the BETA scale reading by 10.
channel devices or to NPN for N-channel devices.
(11) Check the beta value listed in section II,
CAUTION
transistor if the beta value is less than the value
Insulated gate FET's, denoted by the
given.
letter "I" in the listings is section 111 of
(12) Disconnect the test leads from the tran-
accumulations of static charge on the
sistor.
gate. Permanent damage will occur if
b. Leakage Test. Make an in-circuit leakage test
gate voltage rating is exceeded even for
as follows:
a short time. When working on these
(1) Operate the POLARITY switch to PNP or
devices, make sure you and all other
NPN, whichever is applicable.
personnel, and all equipment, including
(2) Operate the FUNCTION switch to ICO, IR.
soldering irons, are grounded. When
(3) Adjust the RANGE switch to X 0.1. Check
testing insulated gate FET's, you must
set the POLARITY switch to a setting
for meter zero. If necessary, zero the meter using
r e v e r s e from that used for normal
the METER ZERO control.
FET's.
(4) Adjust the RANGE switch as required by
the value of the device under test as indicated in
b. Operate the FUNCTION switch to FET.
section II of appendix D. Set to:
c. Set the RANGE switch to X 0.1. Check for
X 0.1 for 0 to 10 A
meter zero. If necessary, zero the meter using the
X 1.0 for 0 to 100 A
METER ZERO control.
X 10 for 0 to 1.0 mA
d. Set the RANGE switch to X 10.
(5) Operate the FUNCTION switch to ICES and
use the ICES ZERO/OHMS ADJ COARSE and
e. Install the transistor into the transistor
FINE controls to zero the meter in this setting.
socket on the front panel. Be sure that gate,
(6) Press and hold the ICES toggle switch to the
drain, and source leads are respectively inserted
READ position and adjust the meter to zero, if
into G, D, and S sockets. If necessary for lead
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