Hickok 539C - Functions of Various Controls; Line Adjustment Control and AC Voltmeter; Selector Switches Operation; Short and Leakage Testing Methods

FUNCTIONS OF THE VARIOUS CONTROLS
3. The line adjustment control rheostat in the 539C Tester is connected with a small
A. C. voltmeter as a constant calibration indicator which is normally always in cir-
cuit. The small A. C. voltmeter may also be used to register 60 cycles A. C. line
voltage fed to the set by operating the test button P7 deSignated "LINE TEST" in the
lower right part of the control panel. Readjust after pressing the P4 Test Button.
4.
Selectors: The row of seven selector switches across the center of the control
panel is for the purpose of conducting proper voltages to the tube's base pins. On
the roll data chart, below the word "Selectors" appear the switch settings.
Example: JR-6237-5. Starting at the left the first switch is set at "}", the ~econd
switch at "R", the third at "6", the fourth "2", the fifth "3", the sixth "7" and the
seventh" 5".
The first two switches control the filament or heater connection~. The other
switches control the GRID, PLATE, SCREEN, CA WODE and SUPPRESSOR in that
order. In the example given above, the heater terminals are connected to pins 8 and
1. The GRID is connected to pin 6; PLATE, to pin 2; SCREEN, to pin 3; CATHODE,
to pin 7 and SUPPRESSOR, to pin 5.
These switches are electrically interlocked in such a way that it is impossible to
connect two different voltage elements to the same pin. Thus accidental shorts are
avoided.
5.
Short Test: In the Model 539C, Hickok has introduced an entirely new concept in short
and leakage testing. In addition to the conventional neon lamp short indication, there
is a d. c. leakage test which registers up to SO megohms on the scale of the large Gm
meter.
Neon Lamp Short Test. Turning the SHORTS switch successively through the posi-
tions 1-2-3-4-5 connects the various pairs of elements inhurn across the test voltage.
Tubes having shorted elements will complete the circuit and cause the neon SHORT
lamp to glow. Tubes may be tested for shorts, either hot or cold. Normal sensitivity
of the neon lamp is about 1/3 Megohni.
A
short is indicated by a steady glow of the neon lamp in certain positions of the
SHORTS switch. A shorted tube should be discarded without further test.
An improved neon Short Test is incorporated in the design of this tube tester. Wide
experience has demonstrated t.":lat most satisfactory results are obtained when tubes
are classified for short test purposes.
The toggle switch is thrown to miniature and subminiature position for all subminia-
ture, button seven pin and button nine pin tubes. The other position is used for tubes
having
regular base pins, including loktal base tubes.
6. Locating Shorted Elements by Neon Lamp. In the following table (X) under any pOSi-
tion indicates that the neon lamp glows in that position.
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