Tektronix SC 501 User manual

INSTRUCTION MANUAL
Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon 97005 Serial Number
070-1700-00
First Printing APR 1974

sc 501
TABLE
OF CONTENTS
Page
SECTION 1OPERATING INSTRUCTIONS
Introduction
Description 1-1
Installation and Removal 1-1
Controls &Connectors 1-2
Operating Considerations 1-3
Deflection Factors 1-3
Applying Signals 1-3
Input Coupling 1-3
Sweep Triggering 1-3
Rear Interface 1-4
Table 1-1 Rear Connector Pin Assignments 1-4
Input Assignments 1-4
Output Assignments 1-5
Electrical Characteristics 1-5
Table 1-2 Vertical Deflection System 1-5
Table 1-3 Horizontal Deflection System 1-6
Table 1-4 Triggering 1-6
Table 1-5 Display 1-7
Table 1-6 Environmental 1-7
SECTION 2SERVICING INFORMATION
Introduction 2-1
Contents 2-1
Maintenance 2-1
Cathode-Ray Tube Replacement 2-1
Test Equipment Required 2-2
Diagrams and Parts Lists 2-3
Electrical Parts List 2-4
Calibration Adjustments
Component Locations (reverse side of foldout)
Block Diagram
Input &Vertical Amplifier (Circuit Description)
Sweep &Horizontal Amplifier (Circuit Description)
Z-Axis &CRT Circuit (Circuit Description)
Low Voltage Supplies (Circuit Description)
Mechanical Parts List
Fig. 1Exploded View
Fig. 2Accessories &Repackaging
CHANGE INFORMATION

sc 501

Section 1—SC 501
OPERATING
INSTRUCTIONS
INTRODUCTION
DESCRIPTION
The SC 501 general purpose oscilloscop)e is designed to
operate in aTM 500 Series Power Module. The SC 501 has
abandwidth of at least 5MHz and acalibrated vertical
deflection range from 10 mV/DIV to 1V/DIV, selectable in
decade steps. An uncalibrated VARIABLE control extends
this range to at least 10 volts/division.
Calibrated sweep rates are selected by pushbutton-
controlled logic in decade steps from 1ms/DIV to
lOOms/DIV (millisecond range) and in decade steps from
1ms/DIV to 100 ms/DIV (microsecond range). A
VARIABLE control extends the slowest calibrated sweep
rate to at least 1second/division and aX5 Magnifier
extends the fastest calibrated sweep rate to at least
200 nanoseconds/division.
The triggering circuits allow stable triggering from either
internal or external sources. An AUTO triggering mode and
manual LEVEL/SLOPE selection is combined in asingle
control. With no input signal, automatic triggering provides
abright baseline at all sweep rates.
An internal switch converts the horizontal deflection
system of the SC 501 to an External Horizontal Amplifier
mode of operation.
INSTALLATION AND REMOVAL
The SC 501 is calibrated and ready for use as received.
Referring to Fig. 1-1, install the SC 501 and turn on the
Power Module. Check that the POWER indicator on the
SC 501 front panel comes on.
NOTE
It is recommended that the Power Module be turned
off before inserting or removing the SC 501. Arcing
at the rear connector terminals can reduce connector
life. However, no internal damage will result if the
SC 501 is inserted in alive Power Module.
Refer to CONTROLS &CONNECTORS (Fig. 1-2) for
description of front panel controls, connectors and
indicators.
©1-1

Operating Instructions—SC 501
CONTROLS &CONNECTORS
NOTE
Switch for Y-T or X-Y
operation located inter-
nally; right side, lower cen-
ter of instrument.
Vertical Input Connector.
BNC connector for vertical
amplifier signal input.
VARIABLE Control
Extends each calibrated
vertical deflection factors
over a10:1 range. Maxi-
mum at least 10 V/Dhr.
Trigger Controls.
LEVEUSLOPE selection
from INT or EXT sources.
Pull LEVEL/SLOPE con-
trol out for AUTO trig-
gering mode.
Sweep VARIABLE and X5
Mag.
Variable controls extends
each calibrated sweep rate
over a10:1 range. Slowest
sweep rata 1sac/Oiv. Pull
variable out for X5 magni-
fication of each calibrated
sweep rata. Fastest cali-
brate sweep rate at least
200 ns/Div.
SC 501 OSCILLOSCOPE
p—;
—
!
I
i
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1
i
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"-ImTUISI
JlTY
EXT HORIZ pin jack.
Operates in conjunction
with internal swit^ to al-
low X-Y operation.
Range
EXT TRIG pin jack.
Allows sweep triggering
from external sources.
Tima/Div
button.
Apush-push switch to al-
low selection of amilli-
second or microsecond
range for the calibrated
Time/Oiv settings.
FOCUS Control
Provides adjustment to
obtain awell-defined dis-
play.
INTENSITY Control.
Controls display brightness.
POSITION Control.
Positions display vertically.
Volts/Div Pushbuttons.
Two self-canceling switches
select the calibrated deflec-
tion factors as indicated.
Toreturn to the
10 mV/Oiv setting, depress
the unused pushbutton just
enough to release the other
pushbutton.
POSITION Control.
Positions display horizon-
tally.
Time/Div Pushbuttons.
Two self-canceling switches
select the calibrated sweep
rates as indicated.
Ground Connector.
Chassis return connector
for signals.
Fig. 1-2. CONTROLS &CONNECTORS.

Operating Instructions—SC 501
OPERATING CONSIDERATIONS
DEFLECTION FACTORS
The amount of vertical deflection produced by asignal is
determined by the signal amplitude, the attenuation factor
(if any) of the probe, the setting of the Volts/Div
pushbuttons, and the setting of the associated VARIABLE
control.
Use the largest deflection factor .(1 V/DIV) when first
connecting the SC 501 to an unknown voltage source. If
the deflection is too small to make the measurement,
switch to alower deflection factor.
The deflection factors indicated by the Volts/Div push-
buttons are calibrated only when the VARIABLE control is
rotated fully clockwise.
The range of the VARIABLE control is at least 10:1. It
provides uncalibrated deflection factors covering the full
range between the fixed settings of Volts/Div pushbuttons.
The VARIABLE control extends the maximum deflection
factor to at least 10volts/division.
APPLYING SIGNALS
While most connections to the SC 501 will probably be
made using coaxial cables, probes offer another convenient
method of applying a' signal to the input of the SC 501.
Tektronix probes are shielded to prevent pickup of electro-
static interference. A10X attenuator probe offers ahigh
input impredance and allows the circuit under test to
perform very close to normal operating conditions. The
SC 501 is compatible with probes such as Tektronix P6006
and P6028 Passive Probes. When probe attenuation is not
desired, aTektronix P6011 Passive Probe is recommended.
NOTE
Probe compensation should be checked with aknown
signal (risetime of 700 nanoseconds or less) before
using the SC 501. Input time constant is normalized
for each attenuator step.
Unshielded test leads can sometimes be used to connect a
signal source to the SC 501, particularly when ahigh-level,
low-frequency signal is monitored at alow impedance
point. However, when any of these factors are missing, it
becomes increasingly important to use shielded cables. In
all cases, the signal transporting leads should be kept as
short as practical. Be certain that acommon ground
connection is established between the device under test and
the SC 501 .The shield of acoaxial cable or ground strap of
asignal probe provides an adequate common ground
connection.
INPUT COUPLING
The AC COUPL pushbutton switch allows achoice of
input coupling. The type of display desired determines the
method of coupling used.
Dc coupling (button out) can be used for most applica-
tions. However, if the dc compronent of the applied signal is
much larger than the ac component, ac coupling (button in)
will probably provide abetter display. Dc coupling should
be used to display an ac signal below ebout 3hertz.
In the ac coupling position, the dc component is blocked
by aseries capacitor in the input circuit. The low-frequency
response in the ac position is about 3hertz (—3 dB point);
therefore, some low-frequency attenuation and phase shift
can be expected near this frequency limit. Distortion will
also appear in square waves that have low-frequency
components.
SWEEP TRIGGERING
When the source switch is in the INT position, the sweep
is triggered by asample of the signal applied to the VERT
INPUT connector. The display is stable for either Normal
or AUTO triggering modes as long as the signal frequency is
above 10 Hz. Below 10 Hz, it may be desirable to use
Normal mode triggering (LEVEL/SLOPE control pushed
in). The AUTO triggering mode (LEVEL/SLOPE control
pulled out) reduces operator adjustments and provides a
bright baseline in the absence of an input signal.
When the source switch is in the EXT position, the
sweep is triggered by the signal applied to the EXT TRIG
pin jack. The signal applied to the EXT TRIG pin jack must
be time-related to the signal applied to the VERT INPUT
connector in order to prevent drift in the display.

Operating Instructions—SC 501
REAR INTERFACE
TABLE 1-1
REAR CONNECTOR PIN ASSIGNMENTS
(REAR VIEW)
Pin No. Left (B) Right (A)
28 Unassigned Unassigned
27 *-t- Gate Out ‘EXT TRIG signal
26 Unassigned ‘EXT TRIG common
23-25 Unassigned Unassigned
22 Unassigned Unassigned
18-21 Unassigned Unassigned
17 ‘VERT INPUT signal ‘EXT HORIZ common
16 ‘VERT INPUT common ‘EXT HORIZ signal
14 Unassigned Unassigned
15 Unassigned Ramp Out
13 Not used Not used
12 +33.5 VFiltered dc +33.5 VFiltered dc
11 Collector PNP Series-Pass Transistor Base PNP Series-Pass Transistor
10 Not used Emitter PNP Series-Pass Transistor
9±33.5 Vdc common ±33.5 Vdc common
8—33.5 VFiltered dc —33.5 VFiltered dc
7Collector NPN Series-Pass Transistor Emitter NPN Series-Pass Transistor
-6 No Connection Base NPN Series-Pass Transistor
1-5 Not used Not used
*Instrument not supplied with these connections. See INPUT and OUTPUT ASSIGNMENT.
NOTE
Refer to Power Module instruction manual for information concerning pins labeled Not used.
INPUT ASSIGNMENTS
The VERT INPUT signal, EXT TRIG signal and EXT
HORIZ signal can be applied through the rear interface
connectors if the SC 501 is modified as follows:
A. VERT INPUT signal.
1. Unsolder the 200 ohm resistor attached to the
VERT INPUT connector. Connect tl\e center conductor
of acoaxial cable to the 200 ohm resistor. Connect the
coaxial cable shield to ground.
2. Connect the other end of the coaxial cable: center
conductor to pin 17B and shield to pin 16B (common).
NOTE
Parallel operation may be obtained if another
200 ohm resistor is connected in series with the
center conductor of acoaxial cable to the junction of
R100 and the main circuit board. The addition of any
coaxial cable to input circuits affects the input
impedance.
B. EXT TRIG signal.
1.Connect the center conductor of acoaxial cable to
the EXT TRIG pin jack. Ground the coaxial cable shield.
2. Connect the other end of the coaxial cable: center
conductor to pin 27A and shield to pin 26A (common).
1-4 REV. B, AUG. 1974

Operating Instructions—SC 501
3. Set the trigger source switch to the EXT position
to trigger the sweep from pin 27A.
C. EXT HORIZ signal.
1.Connect the center conductor of acoaxial cable to
the EXT HORIZ pin jack. Ground the coaxial cable
shield.
2. Connect the other end of the coaxial cable: center
conductor to pin 16A and shield to pin 17A (common).
OUTPUT ASSIGNMENTS
A+Gate Out signal can be routed to the rear interface
connector via the center conductor of acoaxial cable to pin
27B. Shield ground may be any convenient location. A
Ramp Out Signal is factory wired to pin 15A .Other pins
(unassigned) are available at the rear interface connector for
routing signals to and from the SC 501 for specialized
applications. One or more compartments of amulti-plug-in
Power Module can be wired with barriers installed to
provide specific functions between compartments. See
Power Module instruction manual for additional
information.
ELECTRICAL CHARACTERISTICS
PERFORMANCE CONDITIONS
The electrical characteristics are valid only if the SC 501
has been calibrated at an ambient temperature between
-h 20°C and -t-30°C and is operating at an ambient
temperature between 0°C and -h 50°C unless otherwise
noted.
TABLE 1-2
VERTICAL DEFLECTION SYSTEM CHARACTERISTICS
Characteristics Performance Requirements Supplemental Information
Bandwidth Dc to at least 5MHz.
Deflection Factors 10 mV/div, 100 mV/div, and 1V/div.
Accuracy Within 3% of indicated deflection. VARIABLE in XI (fully cw) position:
gain correctly set at 10 mV/div.
Uncalibrated (Variable) Range Continuously variable between steps.
Extends deflection factor to amaximum
of 10 V/div.
10:1 range for all attenuator settings.
Low Frequency Linearity 0.1 division or less compression or
expansion of atwo division (at center
screen) signal when p>ositioned to the top
and bottom of the graticule area.
Input Coupling Ac or dc. Lower bandwidth limit when ac-coupled
is approximately 3Hz.
Input Impedance 1MJ7 paralleled by 47 pF. Input time constant is normalized for
each attenuator step.
Maximum Safe Input Voltage 350 V(dc +peak ac).
REV. B, AUG. 1974 1-5

operating Instructions—SC 501
TABLE 1-3
HORIZONTAL DEFLECTION SYSTEM CHARACTERISTICS
Characteristics Performance Requirements Supplemental Information
Time Base
Calibrated Sweep Rates 1ms/div, 10 ms/div, 100 ms/div, 1ps/div,
10 ps/div, 100 /is/div.
Uncalibrated (Variable) Range Extends slowest calibrated rate to at least
1sec/div.
10:1 range for all calibrated rates.
Zero to 10 Vramp output available at
rear interface connector for all sweep
rates (excluding X5 magnification).
X5 Magnifier (fixed) Extends fastest calibrated sweep rate to
at least 200 ns/div.
Accuracy (Over 8div) Within 5% for all sweep rates. Disregard first 0.5 ps of total sweep
length.
Linearity (any two division
fxartion within center
eight divisions)
Within 5%. Disregard first 0.5 /is of total sweep
length.
External Horizontal Amplifier Internal switch must be set to X-Y
position.
Bandwidth Dcto 100 kHz. Internally calibrated for 100 mV/div.
Input lmF>edance Approximately 100 kJ2 paralleled by
25 pF.
Maximum Input Voltage ±3 V.
TABLE 1-4
TRIGGERING CHARACTERISTICS
Characteristics Performance Requirements Supplemental Information
Normal Trigger Sensitivity (Trigger
LEVEL/SLOPE control pushed in)
Internal: Dc-coupled 0.4 major division of deflection at dc
increasing to 1.0 major division of
deflection at 5MHz.
External: Dc-coupled 1Vminimum to 5Vmaximum from dc
to 5MHz.
Input Impedance 22 Kfi paralleled by approximately
150 pF.
AUTO triggering (Trigger LEVEL/
SLOPE control pulled to out
position)
Sweep free-runs in absence of trigger
signal or for trigger repetition rates below
10 Hz.

Operating Instructions—SC 501
TABLE 1-5
DISPLAY CHARACTERISTICS
Characteristics Performance Requirements Supplemental Information
Graticule
Type Internal black line, nonilluminated.
Area Six divisions vertical by 10 divisions
horizontal. Each division equals
0.203 inch.
Phosphor P31 standard.
TABLE 1-6
ENVIRONMENTAL CHARACTERISTICS
Characteristics Performance Requirements Supplemental Information
Temperature
Operating 0°C to -t50°C.
Storage -40°C to +75‘’C.
Altitude
Operating To 15,000 feet.
Storage To 50,000 feet.
Vibration
Operating and Non-operating With the instrument complete and
operating, vibration frequency swept
from 10 to 50 to 10 Hz at 1minute per
sweep. Vibrate 15 minutes in each of the
three major axes at 0.015 inch total
displacement. Hold 3 minutes at any
major resonance, or in none, at 50 Hz.
Tot^l time, 54 minutes.
Shock
Operating and Non-operating 30 g's, 1/2 sine, 11ms duration, 2 shocks
in each direction along 3major axes, for a
total of 12 shocks.
1-7