Tracker-2800-2800S.pdf - 第19页

19 Figure 2-9 Tracker 2800 LCD Display with Open Test Terminals. Vertical Axis The amount of vertical trace deflecti on on the LCD displa y is controlled by the voltage dropped across the internal impedance R s of the Tr…

Range Volts/Div

20V 5.00

15 V 3.75

10 V 2.50

5 V 1.25

3 V 0.75

200 mV 0.05

Table 2-3 Tracker 2800 Horizontal Sensitivities

The Signature viewing area of the LCD screen can also be set up in quadrants to show positive and

negative current and voltage characteristics. Refer to figure 2-8.

Figure 2-8. LCD Display Horizontal Axis and Graticule Lines.

When the test signal is positive, this means that the voltage and current are positive so the signature's

trace is on the right hand side of the LCD display. When the test signal is negative, the voltage and

current are negative so the trace is in the left hand side of the display.

Turn on the Tracker 2800 and observe the LCD display. With nothing connected to its test terminals,

the display trace is a horizontal line (R

=) as shown in figure 2-9.

Figure 2-9 Tracker 2800 LCD Display with Open Test Terminals.

Vertical Axis

The amount of vertical trace deflection on the LCD display is controlled by the voltage dropped across

the internal impedance R

of the Tracker. Because R

is in series with the load R

, this voltage will be

proportional to the current flowing through R

. This current that flows through the component under

test is the vertical part of the signature.

When the R

is zero ohms (0) by shorting the output terminal to the common terminal, there is no

voltage dropped across R

causing no horizontal component displayed in the Tracker signature. This

short circuit signature is a vertical line trace on the LCD display.

Connect the red microprobe to the output channel A jack on the Tracker 2800 and the black

microprobe to the Common jack. Touch and hold the probes together and observe the Tracker

signature on the LCD display.

You will see a vertical line trace in the middle of the LCD display.

Figure 2-10. LCD Display with Vertical Axis, Graticule Lines displaying a short circuit.

2-9 Four Basic Component Analog Signatures

All Tracker signatures are a composite of one or more of the four basic component signatures which

are: resistance, capacitance, inductance and semi-conductance. Refer to Fig 2-11. Each one of these

basic components responds differently to the Tracker 2800's test signal. Recognizing these four basic

unique signatures on the LCD display is one of the keys to successful ASA troubleshooting. When

components are connected together to form a circuit, the signature at each circuit node is a composite

of the basic component signatures in that circuit. For example, a circuit with both resistance and

capacitance will have a signature that combines the analog signatures of a resistor and capacitor. The

signature of a resistor is always indicated by a straight line at an angle from 0 to 90 degrees. The

signature of a capacitor is always in the form of a circle or ellipse shape. The signature of an inductor

is also a circle or ellipsoid shape that may also have internal resistance. Finally, the semiconductor

diode signature is always made up of two or more linear line segments that most of the time form an

approximate right angle. Semi-conductance signatures can show conduction in both forward and

reverse-bias. This will form a zener semiconductor pattern which will show both junctions.

Figure 2-11. Analog Signatures of the Four Basic Components

Resistance

Capacitance

Inductance

Semi-conductance