advancing the Main Sweep STABILITY control slowly CW, you obtain a trace, and
if further advance of this c ontrol results abruptly in a brightening of the
trace.
(The first trace results from triggering of the sweep by the trigger-
shaper multivibrator operating in a free-running manner at about 50 cps. The
brightening occurs when the sweep-generating circuits themselves become free-
running at advanced Main Sweep STABILITY settings.
Now apply sufficient calibrator signal to provide 2mm of vertical deflection.
Set the TIME/CM control to 1 millisec. A stable display should be obtained
when the Main Sweep STABILITY control is set for triggered operation of the
sweep. A further check on the AC AUTO mode is obtained by removing the input
lead at the calibrator connector. Usually sufficient 60-cps signal will be
picked up in the room so that if the bare end of the lead is held in the hand,
a (distorted) ac wave can be obtained on the screen. The TIME/CM and VOLTS/CM
controls should be s et to obtain a display of suitable size on the screen, and
it should be checked that a stable display can be obtained by setting the Main
Sweep STABILITY control if necessary,
18. To adjust EXT SWP AMPL DC BAL.— Ground EXTERNAL SWEEP IN. Set:
HORIZONTAL DISPLAY--EXT SWP.
EXT. SWEEP ATTEN. (knob)— CW.
5X MAGNIFIER— ON."
ATTEN. (toggle;— XI.
Main Sweep STABILITY— CCW.
Position the s pot on the screen by means of the HORIZONTAL POSITION control.
Adjust EXT SWP AMPL DC BAL control so that the spot remains stationary on the
screen as the EXTERNAL SWEEP ATTENUATOR knob is turned back and forth through
out its range.
19. To set
C2k0
and C25I+.— Settings:
Main Sweep TRIGGERING LEVEL— 0.
TRIGGER SLOPE— +EXT.
TRIGGERING MODE— AC SLOW.
HORIZONTAL DISPLAY— EXT. SWEEP.
SLOPE (toggle)— +
VOLTS/CM— 10.
5X MAGNIFIER— ON
.
ATTEN. (toggle)
— X I .
EXT. SWP. ATTEN.— CW.
TIME/CM— 1 millisec.
"MULTIPLIER— XI.
CALIBRATOR— 0.5 volts.
a. Connect 1-kc output from Type 105 to TRIGGER OR EXT. SWEEP IN. Have the
Type 105 terminated at its output connector with a 52-ohm terminating resis
tor. Use a 52-ohm cable, terminated at the oscilloscope end in a 5*1 (lli-db)
52-ohm L pad. Connect the Sync Output of the Type 105 to TRIGGER INPUT.
Connect SAWTOOTH MAIN SWEEP to input of plug-in preamplifier. Adjust
STABILITY for a stable square-wave display which is presented vertically,
rather than horizontally, across the screen. Set the Output Amplitude con
trol of the Type 105 for about 2 cm of horizontal deflection. Adjust C2i|0
(at right rear of top deck) for best square-wave r eproduction.
b. Next, turn the 5X MAGNIFIER off, and increase the Output Amplitude setting of
—
the Type 105 so that a horizontal deflection of about 2 cm is again obtained.
Adjust C251i (near C2U0) for best square wave reproduction.
August, 1956
f d
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