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Review
• Inductors display elliptical signatures similar to capacitors. Since the inductor also exhibits
resistance, due to its construction, the ellipse may be distorted.
• As the Tracker 2700 test signal’s frequency is increased, the ellipse signature becomes
flatter. This response is opposite to that of a capacitor.
• As the Tracker 2700 internal resistance R
S
increases, an inductor's signature becomes more
vertical (like the capacitor signature).
• When an inductor has a ferrite core, its signature distorts from a non ferrite inductor’s ellipse.
Applications
• The Tracker 2700 is excellent for troubleshooting inductors. It can reveal shorted or open
windings in large variety of inductive components.
• Components that are inductors or have inductive characteristics can be found in many real
world applications. A few examples are, power transformers, relays, solenoids, flyback
transformers, speakers, magnetic sensors, stepping motors and motor windings.
• The best technique for testing inductors is the comparison of a known good component's
signature to a suspect component. For example, a motor armature has typically numerous
windings so every winding should have a similar Tracker signature. This fact is true whether
it's from an elevator or a tape deck. The armature of a DC motor can be tested by simply
connecting to the motor brush leads and then adjusting the test range for the most
pronounced or descriptive signature. Slowly turn the armature. Observe the Tracker 2700’s
LCD display. This test will check continuity, the inductance, and the condition of each brush
contact without disassembling the motor.
• A computer switching power supply contains inductors. For example, a computer is reported
“dead." To make a quick diagnosis of the possible problem first make sure the computer is
disconnected from AC power. Then connect the red and black test probes across the prongs
on the AC line cord going to the computer. Turn the computer power switch to the On
position. If there is a response on the Tracker 2700's display, adjust the test range for the
most pronounced inductive signature. Flick the power switch off and on and watch for noisy
switch contacts. If there is no response, start by checking each component up to the primary
winding of the transformer. With this technique, we have just verified the AC cord, the AC
noise filter, the fuse, the power switch and the primary winding of the transformer, without
removing the cover of the computer.
• Another simple test for a speaker or microphone is to apply the Tracker 2700 signal in 10V,
100Ω, 60 Hz range to the device input leads and listen for the 60 Hz tone or audible hum.
• To test solenoids, connect the test probes to the coil leads and manually move the plunger or
activator in and out while observing if its signature changes.
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