5-33
is present with either positive or negative selected, and 10 volts peak-to-peak when the composite pulse is
active.
Q-10. What minimum/maximum voltage level can be attained in the pulse generator section by
adjusting the LEVEL control?
In the DC mode, a zero-to-5-volts DC level is produced at G1 and G2 on the front panel. The
polarity of the level is controlled by the positive and negative buttons. By pressing the positive button,
you enable a positive DC output and disable the negative button. By pressing the negative button, you
enable a negative DC voltage only if the positive button is in the off position. The WIDTH control knob
has no effect in the DC mode of operation.
CRT Display
The CRT deflection drivers boost the low-level outputs from the signal section to the higher voltage
levels needed by the deflection plates in the CRT. The HORIZ (horizontal) and VERT (vertical) controls
on the front panel adjust the position of the CRT trace. The TRACE ROTATE control on the front panel
is used to adjust the short circuit vertical trace to be parallel with the vertical axis on the CRT graticule.
Three other controls (INTENSITY, FOCUS, and astigmatism) are used to adjust the proper
brightness and clarity of the trace. The front-panel INTENSITY control is the primary way to adjust the
visual quality of the trace. FOCUS is located on the back panel and is used as your trimming adjustment.
Astigmatism is an internal adjustment and is set at the factory.
Power Supply
The power supply is an ac-line-operated power supply that is turned on and off by the
POWER/INTENSITY knob located on the front panel. Once power is turned on, the power supply
provides 12 V dc (nominal) and 5 V dc (regulated) for normal circuit operational use in the oscillator,
pulse generator, signal, and control logic sections of the Tracker 2000.
The other outputs from the power supply are provided to the CRT display section. The CRT is
provided with a filament voltage of 6.3 Vrms, +180 V dc for the deflection driver circuits, and a regulated
-1320 V dc for the CRT acceleration voltage.
COMPONENT TESTING
Now that you have a basic understanding of how the Tracker 2000 works, we will show you a few
examples of different components with values and their associated displays. Because of the large number
of different values that can be given to any component, this section will present only a few.
Testing Resistors
A resistance across the test probes will cause the trace of the Tracker 2000 to rotate in a
counterclockwise direction around its center axis from an open circuit position. The degree of rotation is
directly related to the resistance value. The higher the value, the less rotation will be observed.
LOW RANGE.—The low range is designed to test for resistance values between 1
W and 1K. Figure
5-30 shows the effect of resistance on the angle of rotation in low range. A 1W resistor causes almost 90º
of rotation, and a 50W resistor produces a 45º rotation. A 400W resistor causes a very small rotation
angle. Resistors lower than 1W will appear as a short circuit (vertical trace), and resistance values above
400W will look like an open circuit (horizontal trace).
