Triggering System - Tektronix 7B85 Instruction Manual

Performance Check and Adjustment-7B85
A. TRIGGERING SYSTEM
Equipment Required
Oscilloscope mainframe
Amplifier plug-in unit
Low-frequency sine-wave generator
High-frequency signal generator
Plug-in extender
50
n
cables (2)
Bnc T connector
BEFORE YOU BEGIN, see
TEST POINT AND
ADJUSTMENT LOCATIONS
in the Diagrams section.
Control Settings
Set the 7B85 controls as follows:
TRIGGERING
MODE P-P AUTO
COUPLING AC
SOURCE INT
SWEEP MODE
B DELAY MODE INDEPENDENT
DELAY TIME
TRACE SEP OFF
(~ TIME enable)
SWEEP
POSITION Midrange
TIME/DIV
20/-Ls/DIV
VARIABLE IN (calibrated)
MAG X1
HOLD OFF MIN
A 1. Adjust DC Balance and Slope Balance (R85,
R80)
a. Connect the low-frequency sine-wave generator to
the amplifier unit input with a 50
Q
cable.
b. Set the oscilloscope mainframe intensity and focus
controls for the desired display.
c. Set the low-frequency sine-wave generator and the
amplifier unit deflection factor for a 0.3-div display at
50 kHz. Center the display vertically.
d. Set the TRIGGERING LEVEL control to approximate-
ly 0 (midrange) and TRIGGERING SLOPE to (+).
REV AUG 1981
e. Check for a stable display with TRIG'D light on.
f. ADJUST -R85 (DC Balance) for a stable crt display.
g. Set the SLOPE switch to (-) and check for a stable
display.
h. ADJUST -R80 (Slope Balance) for a stable display.
i. Check for a stable display when the SLOPE switch is
set to (+) and (-).
j. INTERACTION-Repeat the adjustment of R85 (DC
Balance) and R80 (Slope Balance) until a stable display is
obtained while changing TRIGGERING SLOPE.
NOTE
If any of the CHECK parts in the following steps can-
not be met, repeat step A 1.
A2. Check Triggering Modes
a. Remove the 7B85 and plug-in extender; then, install
the 7B85 directly into the A horizontal compartment.
b. Set the low-frequency sine-wave generator and the
amplifier unit deflection factor for approximately a 2-division
display.
c. CHECK-for a stable display at all LEVEL control
settings (P-P AUTO MODE).
d. Set TRIGGERING MODE to AUTO.
5-5