Tektronix 1S1 Instruction Manual page 17

Operating Instructions – Type 1S1
Use either of these methods, as described in the proce-
dures, or make use of some other accurate voltage source.
The differential comparator can be used to check the 5-volt
calibrator amplitude, after which the horizontal deflection
adjustment can be made to within about 2% accuracy with
only the calibrator signal.
Smoothing Balance Adjustment
If the trace (with no signal applied) moves vertically as
the SMOOTHING control is turned, adjust the smoothing
(memory) balance adjustment as follows:
1. Remove the left side panel of the oscilloscope (or ex-
tend a rack-mounted oscilloscope).
2. Locate the MEMORY BAL adjustment control (R110)
shown in Fig. 2-4.
3. Alternately adjust the control, then turn the SMOOTH-
ING control, until there is no vertical trace movement as
the SMOOTHING control is turned.
While the oscilloscope side panel is off, also check the
attenuator and variable balance adjustments and the vertical
position range adjustment as given in the following pro-
cedures.
Attenuator Balance Adjustment
With the dc offset at zero volts and with no signal applied,
if the trace moves vertically on the crt screen as the
mVOLTS/CM switch is turned from one position to another,
adjust the attenuator balance as follows:
2-8
Fig. 2-4. Operational adjustment controls on the left side of the Type 1S1
1. First check and adjust the smoothing balance as de-
scribed above.
2. Set the DC OFFSET control to zero volts by monitoring
the OFFSET OUTPUT jack with a high-impedance voltmeter
or a dc-coupled test oscilloscope. Another method of setting
the dc offset to zero volts is by moving the patch cord con-
nector from the HORIZ OUTPUT jack to the OFFSET OUTPUT
jack to monitor the offset voltage. When the output voltage
is zero, the crt spot will not move horizontally as the patch
cord connector is touched to or removed from the OFFSET
OUTPUT jack.
3. With the mVOLTS/CM switch at 200, position the free-
running trace on the horizontal centerline with the VERT
POSITION control.
4. Set the mVOLTS/CM switch to 2.
5. Locate the BRIDGE BAL adjustment control (R30) shown
in Fig. 2-4.
6. Adjust R30 to reposition the trace to the center of the
crt screen.
7. Repeat steps 3 and 4 to check the adjustment.
Variable Balance Adjustment
With the dc offset at zero volts and with no signal applied,
if the trace moves vertically on the crt screen as the mVolts/
Cm VARIABLE control is rotated, adjust the variable balance
as follows:
1. First check and adjust the smoothing balance and at-
tenuator balance as described above.