Performance Checks And Adjustments - Tektronix MR 501 Instruction Manual

PERFORMANCE CHECKS AND ADJUSTMENTS
a. Check that the correct nominal line selector block
(110 VAC or 220 VAC) has been installed on the line
selector pins and that the regulating range selected
includes the input line voltage, see Installation section of
b. Connect Power Module to the variable auto
transformer and the auto transformer to the line voltage
source.
c. Remove the MR 501 side covers and connect the
Monitor to the Power Module, using the plug-in exten-
sion.
d. Apply power to the MR 501 by setting the auto
transformer to the nominal line voltage that the power
module line selector is set to.
e. Set the following controls:
INTENSITY Fully cow
FOCUS Midrange
Y VARIABLE Fully cw
X VARIABLE Fully cw
Input Coupling DC
Volts/Div 10 mV
t & @POSITION Midrange
| WARNING
Dangerous potentials exist at several points through-
out this instrument. When the instrument is operated
with the covers removed, do not touch exposed
connections or components. Disconnect power before
cleaning the instrument or replacing parts.
2. Check Z Axis Amplifier Gain and Risetime
Connect the test oscilloscope via a 10X
probe to the Z axis amplifier output test point.
Set the oscilloscope time/div control to 1 ms,
input coupling to DC and the volts/div control
to 100 mV.
Note the DC level of the Z axis amplifier; it
should be between 2 and 6 volts. Rotate the
MR 501 INTENSITY control until the Z axis
amplifier DC level just starts to shift upward.
Set the test ostilloscope volts/div control to
5. Connect the known output of the square-
wave generator through a coaxial cable and a
50 ohm termination to the MR 501 Z input
Measure the test oscilloscope waveform
amplitude, it should be within 8 to 11 volts
over the known output of the square-wave
Set the test oscilloscope time/div switch to
1 us and magnify the sweep.
Measure the risetime of the test oscilloscope
waveform, it should not be more than 1.75 us.
—980 V
Test Point
|
Y Amplifier Adjustments
C12 C20
Atten Comp
Z-Axis Amplifier Output
Test Point
1. Power Supply Regulation Checks
Connect a precision DC voltmeter
between ground and the -—20V test
point. Note actual power supply voltage.
Vary the auto transformer output volt-
age from the lower through the upper
line voltage regulating range (see Power
Module manual). Output power supply
voltage must remain within 1% of volt-
age noted above as line voltage is varied.
Repeat test for —980 V test point.
Set auto transformer to nominal line
voltage when check is complete.
—20 V Test Point
5. Check Phasing
Set the MR 501 X and Y amplifier volts/div
pushbuttons for a deflection factor of 10 mV.
Connect the output of the leveled sine-wave
generator through a coaxial cable, 50 ohm
termination and a dual input coupler to the X
and Y input connectors. Set the output fre-
quency of the generator to 50 kHz. Adjust the
sine-wave generator output amplitude control
for a 45° diagonal line across a 6 division by 6
—
Change the generator frequency to 350 kHz.
The center of the 45° diagonal line must not
show more than 1.5 minor divisions of separa-
tion. Disconnect the sine-wave generator.
1.5 minor division
45° diagonal line display
~<——_ 6 division square
NOTE
This procedure must be accomplished
once for each amplifier.
amplitude calibrator, through a coaxial cable,
Connect the output of the levéled sine-wave
generator through a coaxial cable and a 50 ohm
termination to the input connector of the
amplifier being adjusted. Set the output fre-
quency of the generator to 50 kHz. Adjust the
sine-wave generator output amplitude control
until the spots on the MR 501 CRT are exactly
6 major divisions apart for the Y amplifier and
10 major divisions apart for the X amplifier.
Change the generator frequency to 2 MHz and
check that the two CRT spots are at least 4.2
major divisions apart for the Y amplifier and
7.0 major divisions apart for the X amplifier.
Check the other two deflection factors for the
same requirements. Disconnect the sine-wave
S L N A W L S N F A V * 8 S H O A H O A O N V W Y O S A d