Tektronix 1A5 Instruction Manual page 68

Calibration — Type 1A5
4. Adjust DC Vertical Balance (DC BAL -
R170, VAR BAL - R330, POSITION RANGE -
R370)
a. Equipment setup is shown in Fig. 6-4. Locations of test
points and adjustments are shown in Fig. 6-8.
b. Set the POSITION control and STEP ATTEN BAL control
at midrange, the DISPLAY switch to A -В and the VOLTS/CM
control to 20 mV.
c. ADJUST — DC BAL [R170, Fig. 6-8) as necessary to pre ­
vent trace shift while switching the VOLTS/CM control
between the 20 mV and 1 mV positions.
until no trace shift accompanies switching.
6-8
d. Switch the VOLTS/CM control to 20 mV.
e. CHECK — Trace shift while rotating VARIABLE from limit
to limit.
f. ADJUST — VAR BAL (R330, Fig. 6-8) until no trace shift
accompanies rotation of VARIABLE control.
g. CHECK — The UNCAL lamp is on except when VARI ­
ABLE is at CAL position. Return VARIABLE to CAL position.
h. CHECK — Trace is at graticule vertical center.
i.
to graticule vertical center.
Repeat this step
j.
Fig. 6-8. Locations of adjustments for step 4.
ADJUST — POSITION RANGE (R370, Fig. 6-8) to set trace
REPEAT — Steps d through i; then continue with step 5.