TB 9-4931-501-35
10. Focus and Astigmatism
a. Performance Check
(1) Position vertical amplifier (A6) controls as listed in (a) through (d) below:
(a) Channel 1 POSITION control to midrange,
(b) Channel 1 INPUT COUPLING switch to DC.
(c) MODE switch to CH1.
(d) TRIGGER switch to CH1.
(2) Position time base (A4) controls, as listed in (a) through (e) below:
(a) Main triggering:
1
SLOPE switch to +.
2
Mode switch to AUTO TRIG.
3
TRIGGER SOURCE switch to LEFT.
(b) POSITION control as desired.
(c) SWP MAG. switch to X1 (out).
(d) MAIN SEC/DIV switch to 1 ms.
(e) DISPLAY MODE switch to MAIN SWP.
(3) Adjust TI INTENSITY control for a normal display.
(4) Set time base MAIN SEC/ DIV switch to AMP (fully ccw) and adjust TI
FOCUS control fully cw. If displayed spot on TI screen is not round, perform b below. It
may be necessary to readjust INTENSITY control.
(5) Set time base MAIN SEC/DIV switch to 1 ms.
b. Adjustments. Adjust ASTIG
R370 (fig. 3) and TI FOCUS
control simultaneously
to obtain best defined spot on TI screen.
a. Performance Check. Adjust
vertical amplifier (A6) and time
base (A4)
POSITION controls to center trace on TI horizontal graticule line. If trace is not aligned
with TI center horizontal graticule line, perform b below.