Tektronix 485 User Manual

Calibration—485/R 485 Service
c. Adjust A CAL (R1308), located near center rear of
Sweep board, for one marker/div and for exact alignment
of markers at 1 and 9 (center 8 divisions).
20. CHECK A VARIABLE TIM E /D IV
a. Set Time-Mark Generator to 1 ms markers; TIME ON
to 0.1 ms.
b. Push and release VARIABLE TIME/DIV to CCW end.
c. Check for 4 divisions or less between markers.
d. Push VARIABLE TIME/DIV into CAL.
21. ADJUST B REGISTER
a. Set HORIZ DISPLAY to ALT; B TRIGGERING
SOURCE to INT; DELAY TIME POSITION (DTP) to 0.
b. Trigger A and B sweeps on the 0.1 ms markers.
c. Adjust B REGIS (R1325), located next to the B
REGIS test point on Sweep board, for coincidence of the
markers at the beginning of the A and B sweeps.
22. CHECK HORIZONTAL CENTERING
a. Set HORIZ DISPLAY to A.
b. While rotating POSITION (HORIZ) control to ex
tremes, observe both ends of the sweep cross the graticule
center line.
c. If necessary adjust HORIZ CENT (R1150), located
on the center of the B Trigger board.
23. CHECK A SWEEP LENGTH
Greater than 10 but less than 11.5 divisions.
24. ADJUST DELAY START and DELAY STOP
(Located on Sweep Board)
a. Set A TIME/DIV to 0.1 ms; B TIME/DIV to 1 ps;
HORIZ DISPLAY to ALT; DELAY TIME POSITION
(DTP) dial to exactly 1.0; B SOURCE to RUNS AFTER
DELAY TIME; Trigger A on the + SLOPE of the 0.1 ms
time mark.
b. Adjust DELAY START (R918) to get intensified
portion on the second time mark and the pulse on B trace
to just start positive at the front of B trace.
c. Set the DTP dial to exactly 9.0.
d. Adjust DELAY STOP (R925) for the intensified
portion on the tenth time mark and the pulse on B trace to
just start positive at the front of B trace.
e. Repeat steps b through d for indentical B displays at
the two DTP dial settings.
25. CHECK 0.1 ms DELAY LINEARITY
a. Same setup as in step 24, except change time marks
to 50 ms.
b. Turn DTP dial fully CCW. The first marker should be
displayed on B display.
c. Set DTP dial to exactly 0.95. A marker should be
near the middle of B display. Adjust POSITION (HORIZ)
to put B display at midscreen reference position.
d. Set DTP dial to exactly 8.95. The marker should be
within 0.2 div of being at the same midscreen reference. If
necessary make a slight readjustment of DELAY STOP to
get the screen position for a DTP dial reading of 8.95 to
agree with that for a DTP dial reading 0.95. Note that in
this setup one minor DTP dial division corresponds to one
screen division, and these procedures require careful set
tings for repeat reading.
e. Set the DTP dial to settings of exactly 0.45, 0.95,
1.45, 1.95, 2.45, through to 9.45. At each setting observe
the marker position on the B display, noting the maximum
+ and — excursions from the center screen reference
position. The total excursion from most negative to most
positive, should not exceed 1.4 screen divisions (1 div spec
plus ±0.2 div for operator setting of the dial).
26. ADJUST 0.1 ms TIM ING , A and B
a. Set A TIME/DIV to 0.1 ms; B TIME/DIV to 10 ns;
HORIZ DISPLAY to ALT; apply 0.1 ms markers.
b. Set the DTP to 1.00 and align the marker to a
reference point, then turn the DTP to 9.00 and adjust
C882, (behind relay on A Sweep) for zero error at the
reference point.
5-12
REV B, MAR 1979

Tektronix 485 Specifications

General

Brand	Tektronix
Model	485
Category	Test Equipment
Language	English