HP 120A - Rear Access Terminals; Perating Plates

Sect. II Page 4
out regard for the de level involved. In the AC po 
sition the input signal (vertical or horizontal) is cou 
pled to the amplifier through a capacitor which re 
moves the de component from the input wave. This
coupling circuit has a low frequency cut-off at 2 cps;
however, to avoid degrading input pulses or square
waves below 200 cps it is advisable to use de coupling.
WHEN USING DC COUPLING THE AVERAGE VALUE
OF THE DC DETERMINES THE POSITION OF THE
SWEEP ON THE OSCILLOSCOPE. IF YOU ARE UN 
ABLE TO FIND THE SWEEP WITH THE VERTICAL
POSITION CONTROL WHEN USING DC COUPLING,
CHECK THE AVERAGE DC LEVEL TO SEE THAT
IT ISN'T TOO HIGH THEREBY DEFLECTING THE
BEAM OFF OF THE SCREEN. When AC coupled the
maximum de that may be applied is 600 v.
A terminal for CRT intensity (Z-axis) modulation.
IF
Basic operating procedures are illustrated in the
drawings that follow. Directions are given for the
cabinet model but are the same for the rack mount
model except that the placement of the controls is
different.
The first two procedures are complete. The others
are arranged to supplement the first two by showing
the variations possible in using the oscilloscope. An
index to these illustrations follows:
. 2-11 OPERATING PLATES
NOTE
An external capacitor must be connected in the in- FIG.
put lead to the middle input terminal (see Figure 2-5)
if balanced ac coupling is used, since a de signal on 2-3
this terminal will unbalance the amplifier and might 2-4
throw the pattern off of the screen. 2-5
------------- 2-6
2-7
2-8
2-10 REAR ACCESS TERMINALS £-9
2-10
The following terminals are accessible through the 2-11
rear access port of the instrument cabinet: 2-12
2-13
2-14
Horizontal and vertical deflection plates.
TITLE
Internal Sweep-Internal Synchronization
Internal Sweep-External Synchronization
AC Coupling Balanced Input
External Horizontal Input
Vertical Balance Adjustment
Vertical Sensitivity Calibration
Internal Sweep Magnification
Intermediate Calibration
Connection to Deflection Plates
Intensity Modulation Operation
Aligning Scope Trace with Graticule
Connecting External Condensers to
Extend Sweep Time.