Tektronix 516 series, Instruction Manual

Page: 45 / 132

C alibration —
Type
516
and turn the red TRIGGER SELECTOR control to the DC po­
sition. Then, while switching the black TRIGGER SELECTOR
control back ond forth between + INT and —INT., adjust
the INT. TRIG. DC LEVEL adjustment for stable triggering
in both positions. It may be necessary to adjust the A VER­
TICAL POSITION control slightly to obtain stable triggering.
Disconnect the jumper wire and the calibrator signal.
11. PRESET STABILITY R i l l . *
Set the red TRIGGER SE­
LECTOR control to the AUTO, position. Set the PRESET STA­
BILITY control (screwdriver adjustment, front panel) to its
fully counterclockwise position and connect a voltmeter be­
tween the center orm of the PRESET STABILITY potentiometer
and ground (see Fig. 6-7). Next, advance the PRESET STA­
BILITY control clockwise until a trace first appears on the crt.
Note the voltmeter reading for this setting of the control.
Then, advance the PRESET STABILITY control further clock­
wise until the trace brightens and note the voltmeter reading
for this setting. Finally, back off the control until the volt­
meter indicates a reading midway between the two previous
readings. Disconnect the voltmeter.
* A llh o u g h th i* c o n tro l I t sh o w n o n th « T im * Bass G e n e ra to r d r*
c u lt d ia g ra m , It i i m orn c lo s o ly a t to c io in d w ith th o tr ig g e r in g d r *
ew ifry o n d i t i a d ju s tm e n t is th e re fo re in c lu d e d In th is se ction .
Fig. 6 -7 . A d ju s tm e n t o f th e PRESET STABILITY c o n tro l.
Time-Base Generator and H orizontal A m p lifie r
The time-base circuits of the Type 516 should not require
frequent readjustment. As o general rule, if the need for
adjustment is indicated, you should first check all of the
time-base ranges before making any adjustments. Often, only
one control is misodjusted and can be recalibrated according
to the following procedures.
Any nonlinearity present in the time base will generally
be confined to the firs* major division of horizontal deflec­
tion. In these instructions, therefore, we recommend calibra­
ting the time-base circuits on the basis of time markers ap ­
pearing between the second and tenth vertical graticule lines
(one division in from the left- ond right-hand edges of the
graticule).
In the instructions that follow, some of the adjustments
interact to a degree. For this reason, it is important that you
make the adjustments in the proper sequence.
Some of the Horizontal Amplifier adjustments affect the
horizontal position of the crt display. As a result, it will be
necessary to reposition the display with the HORIZONTAL
POSITION control to keep the time markers properly po­
sitioned with respect to the graticule lines.
Set up the Type 516 front panel controls as follows:
TIME BASE
TRIGGER SELECTOR
(red)
AC
TRIGGER SELECTOR
(black)
+ INT.
STABILITY
PRESET
TRIGGERING LEVEL
0
HORIZ. DISPLAY NORM.
TIME/DIV.
1 mSEC.
VARIABLE TIME/DIV.* CALIBRATED
MODE A ONLY
* M o k u iu r « lh « VAR IABLE T IM E /D IV . c o n tro l t t a y i In th o C A L I­
BRATED p o iit lo n d u rin g o il tim in g a d ju tt m o n ti.
12. M A G . G A IN ADJ. R259.
Connect the output of the
time-mark generator to the A VERTICAL input connector
and set tho time-mark generator controls for a 100-micro-
second morkor output. Adjust the Typo 516 A VERTICAL
VOLTS/DIV. control for a vertical doflection of about 3 major
divisions. Center the display on the graticule with the PO­
SITION controls.
To calibrate the magnifier circuit, turn the HORIZ. DIS­
PLAY switch to the MAG. position and adjust the MAG.
GAIN ADJ. so that there are two time markers per major
division.
13. SWP. G A IN ADJ. R225.
Turn the HORIZ. DISPLAY
switch to the NORM, position, remove the 100-microsecond
markers and apply 1000-microsecond (1-millisecond) markers
to the A VERTICAL input connector of the oscilloscope. Ad­
just the SWP. GAIN ADJ. for one marker per major division.
6-6