Use the low range when testing a single
device under test with one of the blue micro clips
bipolar junction, such as a diode, a
provided. The pulse generator has two outputs,
base-emitter junction, or a base-collector
G1 and G2, so you can test three terminal devices
junction. It offers the best signature.
in the alternate mode.
· Use a higher range to check for reverse bias
using the pulse generator selector buttons. First
select the pulse mode or the dc mode using the
When performing in-circuit testing, do a
direct comparison to a known good circuit.
In the pulse mode, the LED flashes at a
The 1000 test leads are not insulated at the
tips. Be sure to make good contact to the
device(s) under test. (NOTE: This tip per-
In dc mode, the LED is continuously on.
tains to the 1000 only.)
When you troubleshoot, try relating the failure
Then select the polarity of output desired using
mode of the circuit under test to the type of defect
the positive (+) and negative () buttons. All
the 1000 shows. For example, expect a cata-
three buttons function in a push-on/push-off
strophic printed circuit board failure to have a
mode, and only interact with each other to avoid
dramatic signature difference from that of a nor-
the NOT ALLOWED state.
mal device of the same type. A marginally operating
After selecting the specific output type, set the
or intermittent board may have a failed part that
exact output using the LEVEL and WIDTH
shows only a small pattern difference from normal.
controls. The LEVEL control varies the magni-
If you cannot relate a system failure to a
tude of output amplitude from zero to 5 volts
specific area of the printed circuit board, begin
(peak or dc). During pulse mode, the WIDTH
by examining the signatures at the connector pins.
control adjusts the duty cycle of the pulse output
This method of troubleshooting shows all the
from a low duty cycle to 50 percent maximum
inputs and outputs. It will often lead directly to
(square wave). The start of a pulse is triggered
the failing area of the board.
by the appropriate zero crossing of the test signal.
Devices made by different manufacturers,
This results in the pulse frequency being equal to
especially digital integrated circuits, are likely to
the selected test signal frequency. The WIDTH
produce slightly different signatures. This is
control setting that selects the duty cycle
normal and may not show a failed device.
determines the end of a pulse. The WIDTH
Remember, leakage current doubles with every
control has no effect when in the dc mode.
10-degree Celsius rise in temperature. Leakage
current shows up as a rounded transition (where
the signatures show the change from zero current
flow to current flow) or by causing curvature at
other points in the signatures. Leakage current
You will use the Huntron Tracker 1000 and
causes curvatures due to its nonlinearity.
the Huntron Tracker 2000 to test various types
Never begin the testing of an integrated circuit
of devices and circuits. Some troubleshooting tips
using the low range. If you initially use the low
are given in this section.
range, confusion can result from the inability of
this range to display the various junctions. Always
Perform most tests using the medium or
begin testing using the medium range. If the
signature is a vertical line, switch to the low range.
Here you can check for a short or low impedance
Use the high range only for testing at a
(less than 500 ohms). Switch to the low range if
the device is suspect and appears normal in the
voltages are required (i.e., to test the
medium range. This will reveal a defective input
Zener region of a 40-volt device).
protection diode not evident when using the
· Sometimes, component defects are more
NOTE: The 2000 test leads are conductive
obvios in one range than another.
only at the tips. Be sure to make good contact with
If a suspect device appears normal for one
the device(s) under test.
range, try the other ranges.