Performance Check/Calibration—Type 422 AC-DC
32. Check Channel Isolation Ratio
a. Change the fo llo w in g control settings:
CH 1 VOLTS/DIV
.01
CH 2 VOLTS/DIV 2
CH 1 Input Coupling GND
CH 2 Input Coupling
DC
X10 GAIN AC Pushed in
TIME/DIV .5 ms
b. Connect the low-frequency sine-wave generator to
the INPUT 2 connector with the BNC to dual binding post
adapter and the 42-inch BNC cable.
c. Set the low-frequency generator for a five-division
display at one megahertz.
d. Set the vertical Mode switch to CH 1.
e. CHECK—CRT display 0.1 division or less in ampli
tude (channel isolation 10,000:1 or greater).
f. Change the following control settings:
CH 1 VOLTS/DIV
2
CH 2 VOLTS/DIV
.01
CH 1 Input Coupling
DC
CH 2 Input Coupling GND
g. Connect the low-frequency sine-wave generator to the
INPUT 1 connector with the BNC to dual binding post
adapter and the 42-inch BNC cable.
h. Set the low-frequency generator for a five-division
display at one megahertz.
i. , Set the vertical Mode switch to CH 2.
j. CHECK—CRT display 0.1 division or less in amplitude
(channel isolation 10,000:1 or greater).
k. Disconnect all test equipment.
Control Setup
When performing a complete procedure, change the
following control settings and proceed with step 33.
CH 1 and CH 2 VOLTS/DIV .05
Vertical Mode CH 1
Partial Procedure
If beginning a partial procedure with this step, set the
controls as given under Preliminary Control Settings.
33. Adjust Channel 1 Only Triggering DC Level
PERFORMANCE CHECK ONLY
Steps 33 through 35 are not applicable to a perfor
mance check. Change the CH 1 Input Coupling
Switch to DC and proceed with step 35.
a. Test equipment required for steps 33 through 53 is
shown in Fig. 5-19.
b. Change the following control settings:
CH 1 Input Coupling GND
TRIGGERING Coupling DC
c. Connect the 10X probe to the vertical input con
nector of the test oscilloscope.
d. Set the test oscilloscope for a vertical deflection fac
tor of 0.01 volt/division (0.1 volts/division at 10X probe
tip) at a sweep rate of 20 microseconds/division with the
input coupling switch set to the ground position.
e. Position the test oscilloscope trace to the center hori
zontal line of the graticule to establish a zero reference
level. Then set the test oscilloscope input coupling switch
to DC.
f. Connect the 10X probe tip to TP364 (trigger compen
sation test point, see Fig. 5-21A). Connect the probe
ground strap to chassis ground. Be sure the probe is com
pensated.
g. Set the LEVEL control to return the test oscilloscope
trace to the center horizontal line (zero reference level).
h. Set the TRIGGERING Source switch to CH 1.
i. CHECK—Test oscilloscope trace within 0.5 division of
the center horizontal line (zero reference level).
NOTE
This tolerance is provided as a guide to correct instru
ment operation and is not an instrument specifica
tion.
j. ADJUST—CH 1 DC Level adjustment R57 (see Fig.
5-20) to position the test oscilloscope trace to the center
horizontal line.
34. Adjust Internal Trigger Compensation
a. Set the Channel 1 Input Coupling switch to DC.
b. Remove transistor Q364 (see Fig. 5-21 A) from its
socket.
c. Connect the square-wave generator high-amplitude
output connector to the INPUT 1 connector through the
GR to BNC adapter, 18-inch 50-ohm BNC cable, two 10X
BNC attenuators and the 50-ohm BNC termination, in given
order.
d. Set the square-wave generator for a one-division dis
play on the test oscilloscope at a frequency of 10 kilohertz
in the high-amplitude mode.
e. CHECK—Test oscilloscope display for optimum
square-wave response similar to Fig. 5-21B (this waveform
5-25
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