Tektronix 2445A - Cal 02-Vertical; Vertical Calibration Signals

Adjustment Procedure-2445A/2455A Service
CAL 02-VERTICAL
2. Check/Adjust Vertical Preamplifier Gain, Gain
(R638), and Vertical Centering (R639).
NOTE
If the previous step (CAL 01) was not performed, the
adjustments in this subsection should only be per-
formed if those constants that would have been set
in
CAL 01 are known to be correct.
a. Set the front-panel INTENSITY control at midrange.
b. Scroll to CAL 02.
c. Press and release the upper TRIGGER COUPLING
switch.
The instrument will automatically increment
through steps 1 00 to 110.
d. CHECK-Readout indicates CH 1 VAR, CH2 POS,
(step) 111, and 500 mV.
NOTE
The readout prompts the operator by showing the
controls to be moved (upper left comer and upper
center), the autocal step number (upper right comer),
the amplitude
of signal to be applied to either the
CH 1
or CH 2 connectors (lower left comer), and any
other scope function that is enabled. An example
(from step d above) is:
CH1 VAR CH2 POS 111
500mV
e. Connect a 0.5-V, standard-amplitude signal from the
Calibration Generator
to the CH 1 OR X input connector
via a
50-n BNC cable.
f. Use the CH 2 POSITION control to vertically position
the trace to within 1 division of the center graticule line.
g. ADJUST
-CH 1 POSITION and VOL TS/DIV VAR
controls to obtain a 1 0-division horizontal signal. Press
and release the upper TRIGGER COUPLING switch.
5-14
NOTE
When step 111 is performed, step 112 is also
automatically
done. No indication of step 112 will be
shown unless a LIMIT error is indicated.
NOTE
In the following steps,
if the ·LIMIT" message
appears,
it probably indicates that the TRIGGER
COUPLING (step) switch was moved before the
required signal was applied. Press and release the
lower
TRIGGER COUPLING switch, verify that the
correct signal is applied, then press and release the
upper
TRIGGER COUPLING switch.
h. CHECK-First step number listed in Table 5-4
appears
in the readout.
i. Apply the corresponding standard-amplitude signal
from the Calibration Generator, then press and release the
upper TRIGGER COUPLING switch.
j. Repeat steps h and i for
each step-signal combination
listed
in Table 5-4.
Table 5-4
Vertical Calibration Signals
Autocal Step
Standard-Amplitude
Readout Display Signal to Apply
113, 114
8
0.5 V
115
0.2 V
116
0.1 V
117
50mV
118
20mV
119
1 V
120 10 V
•when step 113 is performed, step 114 is also automatically
done. No indication of step 114 will be shown unless a LIMIT
error
is encountered.
k. Move the signal to the CH 2 input connector.