Tektronix 535A, Instruction Manual

Page: 59 / 156

Calibration Procedure — Type 535A
Fig. 6-2. Right Side View of the Type 535A Oscilloscope showing the locations of internal controls.
INTENSITY
full left
HORIZONTAL DISPLAY A
TRIGGERING MODE (A and B) AC
TRIGGER SLOPE (A and B) +INT
STABILITY full left, but not PRESET
TIME/CM (A and B)
.5 MILLISEC
VARIABLE
CALIBRATED (full right)
CALIBRATOR OFF
PLUG-IN UNIT
AC/DC DC
VOLTS/CM
.05
VARIABLE
CALIBRATED (full right)
NOTE
Setting for all controls not listed above are not
pertinent to this part of the procedure and the
controls may be left in any position.
Check the rear of the instrument to be sure the metal
strap between EXTERNAL CRT CATHODE and GROUND
binding posts is in place, and that the CRT CATHODE
SELECTOR Switch is away from the DUAL-TRACE CHOPPED
BLANKING position. Connect the instrument and the ac
meter to the autotransformer output and turn on all equip­
ment. Adjust the autotransformer to the design-center volt­
age for which your instrument is wired (117 or 234 v.) and
allow at least 5 minutes warmup before making any adjust­
ments.
PROCEDURE
1. Low-Voltage Power Supplies
Measure the output voltage of the —150 v, + 100 v,
+ 225 v, +350 v and +500 v supplies at the points indicated
on the right side view, Fig. 6-2. Be sure your meter is ac­
curate (see Equipment Required, 6-1). The ouput voltage of
the —150 v supply must be between —147 v and 153 v,
and the other regulated supplies must be within 2% of their
rate values. You should be able to set the —150 v Adj.
control (see Right Side View, Fig. 6-2) so that all of these
voltages are within the specified tolerance. Bear in mind
that the calibration of the entire instrument is affected by
changes in the power supply voltages. Don’t adjust the
— 150 v unless one or more of the supplies is actually out
of tolerance.
6-2