2-11
Always check the condition of the test set batteries by disconnecting the test set power cord, placing
the POLARITY switch in the PNP position and placing the FUNCTION switch first to BAT.1, then to
BAT.2. In both BAT positions the meter pointer should move so as to indicate within the red BAT range.
BETA MEASUREMENTS.—If the transistor is to be tested out of the circuit, plug it into the test
jack located on the right-hand side below the meter shown in figure 2-4. If the transistor is to be tested in
the circuit, it is imperative that at least 300 ohms exist between E-B, C-B, and C-E for accurate
measurement. Initial settings of the test set controls are as follows:
1. FUNCTION switch to BETA
2. POLARITY switch to PNP or NPN (dependent on type of transistor under test)
3. RANGE switch to X10
4. Adjust METER ZERO for zero meter indication (transistor disconnected)
NOTE: The POLARITY switch should remain OFF while the transistor is connected to or
disconnected from the test set. If you determine that the beta reading is less than 10, reset the RANGE
switch to X1 and reset the meter to zero.
After connecting the yellow test lead to the emitter, the green test lead to the base, and the blue test
lead to the collector, plug the test probe (not shown) into the jack located at the lower right-hand corner of
the test set. When testing grounded equipment, unplug the 115 vac line cord and use battery operation.
The beta reading is attained by multiplying the meter reading times the RANGE switch setting. Refer to
the transistor characteristics book provided with the tester to determine if the reading is normal for the
type of transistor under test.
ELECTRODE RESISTANCE MEASUREMENTS.—Connect the in-circuit probe test leads to
the transistor with the yellow lead to the emitter, the green lead to the base, and the blue lead to the
collector. Set the FUNCTION switch to the OHMS E-B position, and read the resistance between the
emitter and base electrode on the center scale of the meter.
To read the resistance between the collector and base and the collector and emitter, set the
FUNCTION switch to OHMS C-B and OHMS C-E. These in-circuit electrode resistance measurements
are used to correctly interpret the in-circuit beta measurements. The accuracy of the BETA X1, X10 range
is 15 percent only when the emitter-to-base load is equal to or greater than 300 ohms.
Ic MEASUREMENTS.—Adjust the METER ZERO control for zero meter indication. Plug the
transistor to be tested into the jack or connect test leads to the device under test. Set the PNP/NPN switch
to correspond with the transistor under test. Set the FUNCTION switch to Ic and the RANGE switch to
X0.1, X1, or X10 as specified by the transistor data book for allowable leakage. Read the amount of
leakage on the bottom scale, and multiply this by the range setting figure as required.
DIODE MEASUREMENTS.—Diode qualitative in-circuit measurements are attained by
connecting the green test lead to the cathode and the yellow test lead to the anode. Set the FUNCTION
switch to DIODE IN/CKT and the RANGE switch to X1. (Ensure that the meter has been properly zeroed
on this scale.) If the meter reads down scale, reverse the POLARITY switch. If the meter reads less than
midscale, the diode under test is either open or shorted. The related circuit impedance of this test is less
than 25 ohms.
