Tektronix 1S1 Instruction Manual page 87

Calibration – Type 1S1
Fig. 5-28. VAR BAL and VERT GAIN screwdriver-adjust
controls on Type 151 front panel.
16. Adjust Variable Balance
a. Continue monitoring the OFFSET OUTPUT voltage
with the test oscilloscope.
b. Recheck the zero dc reference level of the test osci-
lloscope, then set the Input Coupling switch to Dc.
5-24
c. Recheck the OFFSET OUTPUT for zero volts on the test
oscilloscope crt screen and adjust the Type 1S1 DC OFFSET
control if the voltage is not correct.
d. Set the Type 1S1 mVOLTS/CM switch to 50.
e. Turn the mVolts/Cm VARIABLE control through its
range of rotation.
f. Check that the indicator oscilloscope trace does not
move more than about 0.2cm as the control is turned.
g. Adjust the front-panel VAR BAL screwdriver-adjust
control (see Fig. 5-28) if operation of the VARIABLE con-
trol is not correct.
h. Set the mVolts/Cm VARIABLE control to CAL position.
17. Adjust Position Range
a. Leave the DC OFFSET control set for zero volts at
the OFFSET OUTPUT jack.
b. Center the Type 1S1 VERT POSITION control knob so
that the white dot is pointing straight up.
c. Check that the trace is approximately centered
(±½ cm) on the indicator oscilloscope crt screen.
d. Adjust R194 (POSITION RANGE) to position the trace
at the horizontal centerline if it was not already within ½ cm
of the centerline. See Fig. 5-27 for the location of R194.
e. Disconnect the test probe from the OFFSET OUTPUT
jack.
NOTES