Tektronix 535A, Instruction Manual

Page: 65 / 156

Calibration Procedure — Type 535A
BRATED, connect 5 MILLISECOND markers from the Type
180A to the Vertical INPUT and trigger the oscilloscope
for a stable display consisting of 1 marker for each 5 cm.
Next, turn the VARIABLE control full left. The display should
now consist of markers every 2 cm or less. Check to see that
the UNCALIBRATED neon indicator lamp is lit in all posi ­
tions of the VARIABLE control except when switched to the
CALIBRATED position.
ning sweep. Rotate the LENGTH control and check that the
sweep length changes between approximately 3.5 and 10.5
centimeters. If the sweep length range is incorrect, substitute
resistance values for R277 and R278 which will allow the
proper range. R277 is normally between 12 k and 18 k; R278
is usually between 47 k and 68 k.
25. Adjust Time Base A Sweep rates, 50 µsec/
cm to .02 µsec/cm.
Set TIME BASE A TIME/CM to .1 MILLISEC, apply 10
MICROSECOND markers from the Type 180A to the Vertical
INPUT, and adjust the triggering for a stable display. Turn
the 5X MAGNIFIER to ON and horizontally position the
trace so that the first time marker is algined with the cen ­
ter graticule line. Then switch the TIME/CM switch to
50 µ SEC and check for horizontal shift of the first marker.
If shift occurs, adjust C330 (see Top View, Fig. 6-3) until
the first marker of both the .1 MILLISEC and 50 MICROSEC
positions occur at the same point.
Turn the 5X MAGNIFIER to OFF, TIME BASE A TIME/CM
to 10 µ SEC and proceed with the following adjustments:
† C375 only affects the first part of the display. There is con­
siderable reaction between C348 and both 160A and 160C. The
adjustment of C348 and C160A should be repeated back and
forth several times to obtain optimum linearity with correct timing,
after which C160C should be readjusted if necessary. Timing adjust­
ments should be made, as usual, between the first and ninth
centimeter lines of the graticule.
TIME/CM TYPE 180A
Adjustments Observe
10 µ SEC 10 MICROSECOND C160E 1 marker/cm.
1 µ SEC 1 MICROSECOND
C160C
1 marker/cm.
.5 µ SEC 1 MICROSECOND
C160A 1 marker/2cm.
Position 2nd
marker to
2nd line on
graticule
.1 µSEC 10 MC † C375 for lin ­
earity and
C348 for time
1 cycle/cm
2 µ SEC
1 MICROSECOND Check timing
range
2 markers/cm.
5 µ SEC 5 MICROSECOND Check timing
range
1 marker/cm.
.1 µ SEC
X5
50 MC* C364 and
C384
(See Fig. 6-4)
1 cycle/cm
* Couple 50 MC from Type 180A through a small capacitor (100
µµf ) directly to one of the vertical plates of the crt. C364 and
C384 should be set as nearly at the same capacity as possible.
It may be necessary to slightly readjust C375 to obtain best pos­
sible linearity.
26. Check ‘ B’ Sweep Length
Place the HORIZONTAL DISPLAY switch at B, the B'
TIME/CM switch at .5 MILLISEC, and adjust for a free run-
27. Set Delay Start and Delay Stop Adjustments
Set the HORIZONTAL DISPLAY Switch at B' INTENSIFIED
BY 'A'. Apply 500
µ
SEC markers from the time-mark gen­
erator to the oscilloscope vertical input. Set the 'A TIME/
CM switch at 50
µ
SEC and the ‘ B ’ TIME/CM switch at .5
MILLISEC. Adjust the B ’ triggering controls for a stable
display. Rotate the A ’ STABILITY control fully clockwise.
A portion of the display will be brightened. Set the DELAY­
TIME MULTIPLIER control at 1.00. Adjust the DELAY START
(see
right
side view, Fig. 6-2) control
until
the brightened
portion starts at the first time mark (one centimeter from the
start of the trace). Set the DELAY-TIME MULTIPLIER control
at 9.00 and adjust the DELAY STOP (see right side view,
Fig. 6-2) control until the brightened portion starts at the
ninth time mark (nine centimeters from the start of the trace).
Repeat the DELAY START and DELAY STOP adjustments until
a satisfactory setting is obtained for both controls. Set the
DELAY-TIME MULTIPLIER control at 1.00 and place the
HORIZONTAL DISPLAY switch at A' DEL'D BY 'B'. Adjust
the DELAY START control so that the leading edge of the
time mark is at the start of th e trace. Set the DELAY­
TIME MULTIPLIER control at 9.00 and adjust the DELAY
STOP control until the leading edge of the time mark is
at the start of the trace.
28. Adjust Time
Base B Sweep Rates
Place the HORIZONTAL DISPLAY switch at B’ INTEN ­
SIFIED BY ‘ A ’ . Set the 'A' TIME/CM switch at 5
µ
SEC and
the B ’ TIME/CM switch at 50
µ
SEC. Connect 50
µ
second
time markers to the oscilloscope vertical input and adjust the
’ B’ triggering controls for a stable display. Rotate the ‘A'
STABILITY control fully clockwise. Adjust the DELAY-TIME
MULTIPLIER control to place the start of the brightened
portion of the trace at the first marker (one centimeter from
the start of the trace). Place the HORIZONTAL DISPLAY
switch at ‘ A ’ DEL'D BY 'B' and adjust the DELAY-TIME
MULTIPLIER control so that the leading edge of the time
marker is at the start of the trace. Record the DELAY-TIME
MULTIPLIER control setting. Adjust the DELAY-TIME MULTI ­
PLIER control for a setting 8.00 higher than the setting re ­
corded. Adjust C260C (see right side view, Fig. 6-2) until
the leading edge of the ninth time marker is at the start of
the trace.
Repeat the procedure outlined in the previous paragraph
with the 'A' TIME/CM switch at .5
µ
SEC, the 'B' TIME/CM
switch at 5
µSEC
and 5
µ
second markers connected to the
oscilloscope. The adjustment should be made with C260A
(see right side view, Fig. 6-2).
6-8