Tektronix 3A74 Calibration Procedure page 11

CALIBRATION NOTES
12. MICROPHONICS: less than 0.5div of ringing-
type microphonics
Set CH 1 MODE to NORM. JHold the micro-
shock hammer in contact with the top
of the TYPE 561B front panel and allow
the slider to drop. Check for less
than 0.5div of ringing-type microphonics.
Return CH 1 MODE to OFF and repeat
the test for the other three channels,
with only one MODE switch at a time
being set to NORM.
13. ALTERNATE DISPLAY
Must alternate on 2, 8, or 4 channels
at all sweep rates
Set all four MODE switches to NORM.
Position the traces ldiv apart on
the graticule. Set the TYPE 2B67
MODE to SINGLE SWEEP and TRIGGER
LEVEL to AUTO. Depress the TYPE 2B67
MODE switch to RESET and release to
SINGLE SWEEP while checking the sequence
of alternation one step at a time and
at the following TIME/DIV settings:
. LSEC . lmSEC
10mSEC 10uSEC
1mSEC 5uSEC
Repeat the above procedure with several
combinations of channels.
14. CHOPPED MODE
a. Adjust CHOPPED blanking signal
amplitude: >85V P-P a. If TYPE 3A74 is being cali-
Check CH 1 ONLY trigger notse: brated in a 564B and TYPE 547/1Al
<300mV is used as a test scope; trigger
Set all MODE switches to NORM. Set
CHOP-ALT switch to CHOP.
Connect the test scope 10X probe to
the strap at the center of the CRT CATH-
ODE SELECTOR switch (SW225, oscilloscope
rear panel), ground the probe ground
to the oscilloscope ground, and set the
test scope VOLTS/DIV to 1.
July 1969 3A74 11