Ac-Coupled Lower -3 Db Point; Vertical Alt And Chop Modes; Beam Find Functional Check; A And B Trace Separation - Tektronix 2246 1Y Service Manual

n. CHECK—display amplitude is 0.1 division or less,
excluding trace width, on the CH 1, CH 2, and
CH 3 traces.
o. Disconnect the test setup.

22. AC-Coupled Lower -3 dB Point

a. Set:
A SEC/DIV
Vertical MODE
Trigger SOURCE
Trigger MODE
b. Connect function generator (FG 502) output to
the CH 1 input via a 50-Xl BNC coaxial cable and
a 5 0 - fl BNC termination.
c. Set the function generator output controls to
produce a six-division sine-wave display at 10
Hz (with no dc o ffse t).
NOTE
It may be necessary to adjust the
TRIGGER LEVEL control to obtain a
triggered display
d. Set CH 1 Input COUPLING to AC.
e. CHECK—display amplitude is 4.2 division or
more.
f. Set Vertical MODE to CH 2 (CH 1 off).
g. Repeat the procedure for CH 2.
h. Disconnect the test equipment from the 2246 1Y
or 2246 Mod A.

23. Vertical ALT and CHOP Modes

a. Set:
Vertical MODE
CH 1 and CH 2
VOLTS/DIV
CH 3 and CH 4
VOLTS/DIV
CH 1 and CH 2 Input
COUPLING
Horizontal MODE
SEC/DIV
Trigger MODE
Performance Check Procedure—2246 1Y and 2246 Mod A Service
b. Position all traces for two divisions of separation
with the CH 1 trace near the top; then in order
down the graticule area with the CH 4 trace near
the bottom.
c. Set SEC/DIV to 10 ms.
d. CHECK—that four traces are sweeping across
the screen alternately.
e. Set CHOP Vertical MODE On.
50 ms
f. CHECK—that four traces are sweeping across
CH 1 (all others
the screen simultaneously.
off)
VERT
NORM

24. BEAM FIND Functional Check

a. Push BEAM FIND in and hold.
b. CHECK—the signal is visible and compressed
fully within the graticule area as the horizontal
and vertical position controls are rotated through
their ranges.
c. Release the BEAM FIND button.
d. Set all Vertical and Horizontal POSITION controls
at the 12 o 'clock position.

25. A and B Trace Separation

a. Set:
A SEC/DIV
Vertical MODE
Horizontal MODE
B SEC/DIV
A/B SELECT
B Trigger MODE
TRACE SEP
b. Position the CH 1 trace below
zontal graticule line to display the separated B
trace.
c. CHECK—for at least four divisions of upward
CH 1, CH 2,
trace separation between the B trace and the A
CH 3, CH 4,
trace.
ALT (CHOP off)
d. Set TRACE SEP fully CCW.
10 mV
e. Position the CH 1 trace above the center hori­
0.1 V
zontal graticule line to display the separated B
trace.
DC
A
f.
CHECK—for at least four divisions downward
1 ms
trace separation of the B trace from the A trace.
AUTO LEVEL
1 ms
CH 1 (others
off)
ALT
0.5 ms
B
RUNS AFTER
Fully CW
the center hori-
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