Display; Display; Check/Adjust Astigmatism And Focus; Check/Adjust Trace Rotation - Tektronix 221 Instruction Manual

Calibration—221 Service
Equipment Required
1. Time mark generator
Control Settings
Preset the controls as given in the Preliminary Control
Setting. See Fig. 5-3 and Fig. 5-4 for locations of adjust­
ment controls.

6. Check/Adjust Astigmatism and FOCUS

a. Set the SEC/DIV switch to the 1 V position (x-y
mode)
b. Set the INTENSITY control fo r a small spot, near
center o f screen.
c. Check that the spot is round.
d. Adjust the FOCUS side panel screwdriver adjustment
and the Astig. adjustment for a round spot.

7. Check/Adjust Trace Rotation

a. Set the SEC/DIV switch to 1 m.
b. Position the trace to the graticule center line.
c. Check that the trace
horizontal line.
d. Adjust Trace Rotation R751 (screwdriver adjustment
on sidepanel) fo r a trace that is parallel w ith the horizontal
graticule lines. See Fig. 5-4.
Astig Adjust
R752
Fig. 5-3. Location of Astigmatism and CRT Unblanking adjust­
ments.
5-6
http://manoman.sqhill.com
is parallel to the center
Rear View
r

DISPLAY

2. Three-inch screwdriver
3. Adapter (probe tip to BNC)

8. Check/Adjust CRT Unblanking

a. Set the INTENSITY to maximum, and set the
SEC/DIV switch to 1 /i.
b. Adjust unblanking adjustment R753 (see Fig. 5-3)
so that retrace is just blanked out.

9. Check Geometry

a. Preset the instrument controls as given in Preliminary
Control Setting.
b. Set the SEC/DIV switch to the 1 millisecond position,
and INPUT COUPLING to DC.
c. Connect the time mark generator to the probe by an
adapter (probe to BNC). Set the markers fo r 1 millisecond.
d. Set the VO LTS/D IV switch setting fo r a full-screen
deflection.
e. Check that vertical and horizontal bowing is less than
0.1 division.
Step Atten Bal
Fig. 5-4. Location of Step Attenuator Bal, Probe Compensation,
and Focus adjustments.
R135 C l 12
REV C, MAY 1978
Probe Comp