1730–Series Theory of Operation
4–23
2-FIELD SWEEP
SELECTED LINE
(LOW)
INTENSIFIED LINE
A3Q346 & A3Q347
FRONT PANEL INTENSITY LEVEL
2-LINE SWEEP
READOUT
ELEMENTS
READOUT
TIME
INTENS
CONTROL
SETTING
BLANK
BLANK 2
ROEN
Z-AXIS OUT
(ANALOG)
Z-AXIS OUT
(ANALOG)
ROEN
BLANK 2
BLANK
a.
b.
READOUT INTENS-
SETTING
Figure 4-9: Z-axis timing for readout: a) Two-field display intensifies the
line (lines) to provide a bright-up strobe. b) In 1- or 2-line sweep, alpha
numeric readout in the upper left corner of the CRT is used to convey the
number of the first selected line.
Trace rotation compensates for changes in the magnetic field surrounding the
1730-Series. Q142 and Q143 are emitter followers to provide Trace Rotation
current to the CRT surrounding coil located inside the CRT shield. Amplitude
and polarity are controlled by the front-panel ROTATE screwdriver adjustment.
U263A is a triangle generator whose output is compared to the front-panel
SCALE control output level, by U263B (a comparator). Whenever the output of
U263A is higher than the level from the front-panel SCALE control, Q158 is
turned on and current is drawn through the bulbs (DS100, DS200, and DS300) to
ground. The duty cycle of Q158 is determined by the level set by the front-panel
SCALE control.
J100 is normally in the 1-2 (Lights Enabled) position. In the 2-3 position, the
graticule scale illumination is disabled.
The + and –15 V supplies generated by the main low voltage power supply are
further regulated to meet the power requirements of the Main (A3) circuit board.
U164 is the regulator; its reference level is set by R167, the -11.8 V Adjust.
U172 is the +11.8 V supply regulator and its reference level is set by R168, the
+11.8 V Adjust.
Trace Rotation
Graticule Illumination
$ 11.8 V Regulators
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