Tektronix 213 DMM - Page 72

Cal ibration-213 Service
f. Disconnect the Digital Voltmeter.
g. If the batteries were not charged at the beginning of
the calibration procedure, reconnect the instrument to
the power line.
4. CHECK/ADJUST CRT GRID BIAS
a. Connect the Digital Voltmeter between TP527 (Beam
.28 V) and common.
b. Set INTENSITY fully clockwise.
c. CHECK-Reading is +0.28 V ± .01 V.
d. ADJUST -Grid Drive, R535, for reading of +0.28 V.
5. CHECK/ADJUST UNBLANKING, FOCUS, AND ASTIG-
MATISM
a. ADJUST -Blank, R580, for maximum brightness (re-
duce INTENSITY as required to maintain a visible trace
without blooming).
6-6
b. Set SEC/DIV to .5 (spot will slowly sweep across the
screen).
c. CHECK-Spot is well defined.
d. ADJUST - FOCUS, R565 and Astig, R575, for the
best spot definition.
e. Reset SEC/DIV to 1 m.
6. CHECK/ADJUST TRACE ROTATION
a. Vertically position the trace on the center horizontal
graticule line.
b. CH ECK- Trace is parallel to the center horizontal
graticule line.
c. ADJUST-TRACE ROTATE, R570, to make trace
parallel to the center horizontal graticule line.
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