Tektronix 556 User manual

INSTRUCTION
MANUAL
Serial Number ___________
TYPE
556
OSCILLOSCOPE
Tektronix, Inc.
S.W. Millikan Way • P. O. Box 500 • Beaverton, Oregon 97005 • P one 644-0161 • Cables: Tektronix
070-0757-00 1167

or service.
Specifications and price c ange privi
leges reserved.
Copyrig t © 1966, new material 1967
by Tektronix, Inc., Beaverton, Oregon.
Printed in t e United States of America.
All rig ts reserved. Contents of t is pub 
lication may not be reproduced in any
form wit out permission of t e copyrig t
owner.
Type 556
WARRANTY
All Tektronix instruments are warranted
against defective materials and workman 
s ip for one year. Tektronix transformers,
manufactured in our own plant, are war 
ranted for t e life of t e instrument.
Any questions wit respect to t e war 
ranty mentioned above s ould be taken
up wit your Tektronix Field Engineer.
Tektronix repair and replacement-part
service is geared directly to t e field,
t erefore all requests for repairs and re 
placement parts s ould be directed to
t e Tektronix Field Office or representative
in your area. T is procedure will assure
you t e fastest possible service. Please
include t e instrument Type and Serial or
Model Number wit all requests for parts

CONTENTS
C aracteristics
Operating Instructions
Circuit Description
Maintenance
Performance C eck
Calibration
Abbreviations and Symbols
Parts Ordering Information
Electrical Parts List
Mec anical Parts List Information
Mec anical Parts List
Diagrams
Mec anical Parts List Illustrations
Accessories
Abbreviations and symbols used in t is manual
are based on or taken directly from IEEE Stand 
ard 260 "Standard Symbols for Units", MIL-STD-
1 2B and ot er standards of t e electronics indus 
try. C ange information, if any, is located at t e
rear of t is manual.
Type 556
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
Section 7
Section 8
Section 9

Sorial number 2000 and up.
Serial number 999 and below.
Fig. - . Type 556 Oscilloscopes.
Type 556

Type 556
SECTION 1
CHARACTERISTICS
C ange information, if any, affecting t is section is found at t e rear of t e manual.
Introduction
T e Type 556 Oscilloscope — is a versatile dual-beam labor 
atory type instrument providing accurate voltage and time
measurements in t e DC to 50 MHz frequency range. Two
complete orizontal and vertical deflection systems permit
completely indepentent operation of t e two beams.
T e Upper Beam can display t e signal from eit er t e
left or rig t vertical plug-in unit and may be controlled by
eit er t e A or B time base or an external signal. T e Lower
Beam displays t e signal from t e rig t plug-in and t e sweep
is controlled by t e B time base or an external signal. T e
left and rig t plug-in compartments accept all letter series
and 1 -series plug-ins.
Special circuits wit in t e oscilloscope provide selection
of an accurate, continuously-variable delay w en using t e
B sweep. T e B sweep may be delayed by t e A sweep from
0.1 µs to 50 s (calibrated) after application of a trigger pulse.
T is feature permits t e delayed B sweep to expand a
selected portion of t e undelayed A sweep, t ereby pro 
viding precise time measurements and detailed observation
of t e signal. Bot t e delayed and undelayed sweeps can
be presented simultaneously on t e oscilloscope screen. T e
Upper Beam trace as an intensified zone indicating t e por 
tion of t e signal being displayed by t e B sweep and Lower
Beam.
T e instrument is designed to operate over an ambient
temperature range of 0° C to +50° C. Performance speci 
fications t at are given in t e center column apply over t is
temperature range after a warmup time of 20 minutes. Sup 
plemental information describing a c aracteristic or a feature
is also included in t is portion of t e manual.
VERTICAL AMPLIFIERS
C aracteristics
Performance Specification Supplemental Information
Frequency Response
DC to >50 MHz at 3 dB down wit a 1 -series
plug-in unit aving a risetime of 3.12 ns or less.
Risetime
<6.25 ns. Indicated risetime of 6.93 ns
wit a Test Load Plug-In Unit (Tektronix
Part No. 067-0521-00) aving a risetime
of 3 ns.
Transient Response on Screen
<2.25% peak overs oot, rounding, ringing or
tilt.
Applies to all t ree vertical modes wit
Test Load Plug-In Units.
Gain C ange wit Line Voltage
C ange
<1% from 147 VAC peak to 178 VAC peak.
Trace Drift wit Line Voltage
C ange
±2 mm from 147 VAC peak to 178 VAC peak.
A & B SWEEP GENERATORS
Calibration Accuracy
5 s/cm to 0.1 µs/cm
±3% of displayed time between two points
displayed wit in t e middle 8 cm.
X10 Magnified Display
±5% of displayed time between any two
points >1 cm apart displayed wit in t e
middle 8 cm.
Calibrated from 4 cm to 70 cm from
sweep start. Extends fastest sweep rate
to 10 ns/cm.
Variable Time/Cm Range
>2.5:1.
Extends slowest sweep to approximately
12.5 s/cm.
Sweep Lengt
10.5 cm ±0.5 cm
At 1 ms/cm.
VARIABLE TIME DELAY
Delay Time Accuracy
5 s/cm to 1 µs/cm
±1% of indicated delay time ±2% of A
TIME/CM setting + fixed delay of <150 ns
in system.
1% of A TIME/CM setting corresponds
to 1 minor division on t e DELAY-TIME
MULTIPLIER dial.
0.5 µs/cm to 0.1 µs/cm
±1 % of indicated delay time ±5% of A
TIME/CM setting + fixed delay of <150 ns
in system.
For additional information refer to Fig.
2-10 in t e Operation Instructions.
-

Characteristics — Type 556
C aracteristics
Performance Specification
Supplemental Information
Incremental Delay Time Accuracy
5 s/cm to 1 µs/cm
±1% of indicated incremental delay
time ±4% of A TIME/CM setting.
Incremental Delay Time is t e difference
between two delay time readings.
0.5/is/cm to 0.1 µs/cm
±1% of indicated incremental delay
time ±7 % of A TIME/CM setting.
For additional information refer to Page
2-24 in t e Operating Instructions.
S ort Term Jitter
<1 part in 20,000 of t e available delay time.
EXTERNAL HORIZONTAL AMPLIFIERS
Ext. Horizontal Deflection Factor
<0.1 V/cm wit DISPLAY MAG in X10 posi 
tion.
Transient Response
±3% peak overs oot, rounding, ringing or tilt.
Variable Range
>10:1
Frequency Response
DC to >400 kHz at 3 dB down. VARIABLE
control set fully cw.
Maximum Input Voltage
50 V combined DC -|- peak AC. Wit DISPLAY MAG in X10 position.
Input C
Approximately 65 pF.
A & B TRIGGERING FEATURES
C aracteristic
Feature
Source
Internal Normal (from left or rig t trigger pick-off circuit wit in t e vertical amplifier),
Internal Plug-In (from one of t e c annels in t e left or rig t Type 1A1 or 1A2 Plug-In
Unit), Line and External.
Coupling
Capacitive (AC), low-frequency reject (AC LF REJ), ig -frequency reject (AC HF REJ) or
direct (DC).
Slope
Triggering on positive-or-negative-going portion of triggering signal.
Mode:
Auto Stability
Free runs sweep in absence of a triggering signal; instrument can be triggered on signals
>30 Hz.
Triggered
Triggered at an adjustable level.
Jitter
<2 ns.
LEVEL Control Range:
Normal
> ±2V.
X10 Increase
> ±20 V.
External Trigger Input:
R & C
Approximately 1 mego m paralleled by approximately 35 pF.
Volts
50 V maximum (DC plus peak AC).
A & B TRIGGERING SENSITIVITY
INT PLUG IN C aracteristics t at apply for t e EXT trigger input also apply to t e Int Plug-In interconnection
(pin 5 of plug-in connectors JI 1 and JI 2).
Trigger Coupling/Source
To 10 MHz
To 50 MHz
AC:
INT NORM
< 2 mm display amplitude
above 60 Hz.
< 1 cm display amplitude.
EXT
< 0.2 V above 60 Hz. < 0.4 V.
AC LF REJ:
INT NORM > 3 cm display amplitude
at 30 Hz.
< 2 mm display amplitude
above 2.5 kHz.
< 1 cm display amplitude.
EXT > 3 V at 30 Hz.
< 0.2 V above 2.5 kHz.
< 0.4 V.
AC HF REJ:
INT NORM <2 mm display amplitude
from 60 Hz to 60 kHz, >1 cm
at 6 MHz.
EXT <0.2 V from 60 Hz to 60 kHz,
> 1 V at 6 MHz.
DC
INT NORM
< 3.5 mm display amplitude.
< 2 cm display amplitude.
EXT
< 0.2 V.
< 0.4 V.
1-2

Characteristics — Type 556
AMPLITUDE CALIBRATOR
C aracteristic
Performance Specification
Supplemental Information
Voltage Accuracy ±2%.
5 mA Current Loop Accuracy ±2%.
Repetition Rate
1 kHz ±25%
Duty Cycle
45% to 55%.
Risetime
< 1.5 µS. 70 pF load.
Terminated Voltage Accuracy
One- alf indicated voltage ±2% w en termi 
nated into 50 o ms ±0.1%.
Applies to AMPLITUDE CALIBRATOR
switc positions from 0.2 mV to 0.2 V
only.
Z AXIS INPUTS
Sensitivity I
10 V P to P causes noticeable modula 
tion intensity.
Input R at DC 1
1 mego m ±10%.
FRONT-PANEL OUTPUT SIGNALS
A GATE
> 8 V positive-going pulse.
Wit baseline at zero volts. Time coin 
cident wit t e A sweep. Maximum
current is 10 mA. Recommended load
resistance >1 k.
B GATE
> 8 V positive-going pulse. Wit baseline at zero volts. Time coin 
cident wit t e B sweep. Maximum
current is 10 mA. Recommended load
resistance >1 k.
DLY'D TRIG
> 7 V positive-going pulse into a >1 k load. Pulse occurs at t e end of t e A sweep
delay period.
A SAWTOOTH
> 9V/cm.
Has t e same time duration as t e A
sweep. Recommended load resistance
>30 k.
B SAWTOOTH
> 9V/cm.
Has t e same time duration as t e B
sweep. Recommended load resistance
>30 k.
Line Frequency
50 Hz to 60 Hz
400 Hz wit special fan modification.
Power Consumption
±840 W maximum. ±1 kVA maximum.
T ermal Protection
An automatic resetting t ermal cutout
interrupts instrument power if internal
temperature exceeds safe operating
level.
POWER SOURCE REQUIREMENTS
For serial numbers 2000 and up
Regulating Range Selection: AC RMS Operating
Range (<2% armon 
ic distortion of t e in-
AC Peak Operating
Range (>2% armon-
is distortion 1 )
put power waveform)
115 Volts
LO 90 to 110 V 127 to 156 V
A Line Voltage Selector assembly facilit-
M
104 to 126 V 147 to 178 V
ies selection of a regulating range com-
patible wit t e actual line voltage.
HI
112 to 136 V
158 to 192 V
230 Volts
LO
180 to 220 V
254 to 311 V
M 208 to 252 V
294 to 356 V
HI
224 to 272 V 316 to 384 V
_ Peak V
Crest Factor ~ — between .30 and .4 4.
-3

Characteristics — Type 556
C aracteristic
Performance
Specification
Supplemental Infromation
For serial numbers 100-1999
Normal Line:
AC RMS Operating
Range (<2% armon 
ic distortion of t e in 
put power waveform)
AC Peak Operating
Range (>2% armon 
ic distortion 1 )
115 VAC Nominal
100 to 130 V
142 to 183 V Normally wired at t e factory for t is
voltage unless directed ot erwise.
230 VAC Nominal
200 to 260 V 284 to 366 V
Low Line:
104 VAC Nominal
90 to 117 V 127 to 165 V
208 VAC Nominal 180 to 234 V 254 to 330 V
CRT AND DISPLAY
2 Crest Factor = ------------- — between .30 and .4 4.
C aracteristic
Information
Tube Type
T5560-31-1. Dual-Beam, round, glass envelope. Tektronix Part No. 154-0500-00.
P osp or
P31 standard. Ot ers available on special order.
Accelerating Potential Approximately lOkV; gun potential is 2 kV.
Scan Area >6 cm vertical by 10 cm orizontal per beam. Beams can be overlapped in a 4 cm area.
Graticule Type
Internal. 8 cm vertical by 10 cm orizontal. Eac major division is 1 cm; four corners are
omitted.
Graticule Illumination
Variable edge lig ting.
Internal Unblanking DC-coupled to CRT control grids from t e Sweep Generators.
Ort ogonality Wit in ±1%.
Trace Rotation Range
Sufficient to align traces wit t eir respective graticule lines.
Beam Finder Limits traces wit in graticule area.
ELECTROMAGNETIC INTERFERENCE
Electromagnetic Interference
Meets interference specifications of MIL-I-6181D over t e following frequency ranges:
Radiated (wit CRT mes filter, cabinet covers and BNC connector covers installed) — 150
kHz to 1 GHz; conducted (power line) — 150 kHz to 25 MHz.
MECHANICAL CHARACTERISTICS
Construction Aluminum alloy c assis, panel and cabinet. Glass laminate etc ed circuit boards.
Finis
Anodized front panel. Blue vinyl-finis ed cabinet and rear panel.
Overall Dimensions: Measured at maximum points; 15 inc es ig , 16- 7 / 0 inc es wide, 24 inc es deep.
ENVIRONMENTAL CHARACTERISTICS
T e Type 556 as been designed to operate over a temper 
ature range of 0° C to +50° C, altitude up to 15,000 feet.
T e non-operating storage temperature range is — 40° C to
+65° C, altitude up to 50,000 feet. After storage at eit er
extreme, t e instrument must be allowed at least 4 ours time
for all components to return to t e ambient temperature range
0° C to +50° C before operating.
Furt er information on environmental test procedures may
be obtained by contacting your local Tektronix Field Office
or representative.
ACCESSORIES
Standard accessories supplied wit t e Type 556 can be
found on t e last pullo-ut page of t e Mec anical Parts List
Illustrations. For optional accessories see t e Tektronix, Inc.
catalog.
-4

Type 556
SECTION 2
OPERATING INSTRUCTIONS
C ange information, if any, affecting t is section will be found at t e rear of t e manual.
General
T is section of t e manual provides for t e effective use of
t e instrument by describing t e function and operation of
t e front panel controls and connectors, listing t e first time
and general operating instructions and presenting some basic
applications.
Nomenclature and Terminology
For reference and guidance, t ese terms are defined as t ey
are used in t is manual.
Alternate Mode — A time-s aring met od of displaying
t e output signals of two or more c annels wit a single
cat ode ray tube beam. C annel switc ing is sequential and
occurs at t e end of t e sweep.
Chopped Mode — A time-s aring met od of displaying
output signals of two or more c annels wit a single cat ode
ray tube beam, in sequence, at a rate not referenced to t e
sweep.
Chopping Rate — T e rate at w ic c annel switc ing
occurs in C opped Mode.
Chopping Transient Blanking — T e process of blanking
t e indicating spot during t e switc ing periods in C opped
Mode.
Dual-Beam Oscilloscope — An oscilloscope in w ic t e
cat ode ray tube produces two separate electron beams
t at may be individually or jointly controlled.
Dual-Trace — A mode of operation in w ic a single beam
in a cat ode ray tube is s ared by two signal c annels.
Multi-Trace — A mode of operation in w ic a single beam
in a cat ode ray tube is s ared by two or more signal c an 
nels.
Signal Channel — A signal amplifying circuit in a plug-in
unit. Wit dual and multi-c annel plug-ins, t e c annels are
generally designated C annel 1 (or A) C annel 2 (B), etc.
Power Requirements
T is instrument may be operated wit power from eit er
a 115-volt or a 230-volt (nominal) power source. Wit proper
positioning of t e Line Voltage Selector connectors, t e power
supply circuit will provide correct DC voltages wit adequate
regulations wit any line voltage wit in voltage limits of
90 to 136 volts RMS and 180 to 272 volts RMS and frequency
limits of 50 to 60 Hz. T e adjustable turns ratio design of
t e power transformer provides t e means of making t e
instrument compatible wit t is wide range of power source
voltages.
SN 2000-up
A Line Voltage selector assembly is provided to facilitate
c anging t e power transformer turns ratio (see Fig. 2-1).
T e assembly contains two line fuses and two movable pins
and socket type connectors. T e two-position connector is
termed t e Voltage Selector and t e t ree-position connector
is termed t e Range Selector.
Table 2-1 lists t e six Voltages and Range selector com 
binations and t e line voltage ranges t ey s ould be used
wit . Before connecting t e instrument to a power source,
measure t e power source line voltage and position t e Volt 
age and Range selectors accordingly.
TABLE 2-
Voltage
Selector
position
Range
Selector
position
Will provide optimum
regulation for line
voltages from
115 V LO
90 to 110 volts
115 V
M 104 to 126 volts
115 V
HI 112 to 136 volts
230 V LO 180 to 220 volts
230 V
M
208 to 252 volts
230 V
HI 224 to 272 volts
To c ange t e power transformer from one regulating
range configuration to anot er use t e following procedure:
1. Disconnect t e instrument from t e power source.
2. Loosen t e two captive screws and remove t e cover.
Since t e line fuses are attac ed to t e cover, t ey will be
pulled from t eir olders wit t e cover.
3. To c ange nominal line selections, pull t e Voltage
Selector until its pins are.free of t e sockets, invert t e selec 
tor and reseat t e pins in t e desired sockets.
NOTE
115-volt to 230-volt plug adapters are not sup 
plied wit t is instrument. If a suitable adapter
is not available, it may be necessary to c ange
t e line-cord plug.
4. To c ange regulating range selections, pull t e Range
selector until its pins are free of t e sockets, move it to t e
desired range position and seat t e pin in t e sockets.
5. Replace t e assembly cover and t e two line fuses. Press
t e cover firmly onto t e assembly to seat t e two fuses in
t eir olders, t en tig ten t e captive screws.
6. T e indicating tabs on t e selectors will be protruding
t roug t e covers to indicate t e selected regulating range.
Always c eck t e position of t ese tabs before applying
power to t e instrument.
2-

Operating Instructions — Type 556
SN 00- 999
Instruments wit serial numbers 100-1999, unless tagged
ot erwise, are connected at t e factory for operation at 115
volts (nominal). T e power transformer as eig t primary
terminals w ic are connected to solderless pin connectors
on t e Power board. T ese quick-c ange connectors make
possible operation from four different nominal AC voltages:
104, 115, 208 and 230 V, 50 to 60 Hz. Fig. 2-2 illustrates
t e jumper and lead connections required for operation on
eac of t e stated line voltages. For 208 V and 230 V opera 
tion, t e two unused jumpers can be stored on t e unused pins
of terminals J and T. All lead connections to t e board t at
are not s own in Fig. 2-2 remain as t ey are.
No c ange in fan connections is required w en c anging
t e connection on t e board as directed in t e illustration.
NOTE
Two metal tags (printed on eac side) are pro 
vided at t e rear of t e instrument to indicate t e
four nominal line voltages. If t e primary wiring
is c anged, be sure to use t e proper tag to indi 
cate t e voltage for w ic t e instrument is wired.
Temperature considerations
To reduce operating temperatures, air is drawn in t roug
t e filter at t e rear and blown forward t roug t e instru 
ment. For t e most efficient air circulation and eat dis 
sipation, provide at least t ree inc es clearance at t e rear,
two inc es at t e sides and operate t e instrument wit t e
side covers installed. If t e fan becomes inoperative or t e
air circulation is obstructed, t o internal temperatures will
exceed a safe operating level in a relatively s ort period of
time. To prevent damage to t o components from excessive
temperaturos, a t ermal cutout switc is incorporated in t o
power supply circuitry. T is switc is designed to interrupt
power to t o instrument w en t e ambient temperature ex 
ceeds about 140° F.
CAUTION
Since t e t ermal cutout switc will reset w en its
ambient temperature decreases to some level be 
low its actuating temperature, set t e POWER
switc to OFF before attempting to remedy t e
cause of t e ig temperature condition.
CONTROLS AND CONNECTORS
Figure 2-3 s ows t e location of all t e instrument operat 
ing controls and connectors. A brief description of eac type
of control and connector is given in t e following table.
Controls wit t e same nomenclatures generally perform
identical functions for t eir respective beams and a descrip 
tion for one is applicable to t e ot er. T ose controls wit
t e same nomenclature, but wit differences in t eir func 
tions, are pointed out and described as separate typ e con 
trols.
Some of t e controls and connectors, particularly t ose
wit complex functions or multiple applications, are de 
scribed in greater detail under General Operating Instruc 
tions.
A AND B TRIGGERING CONTROLS
Source Selects triggering signal source, Two selec 
tor switc es are combined under t e no 
menclature of SOURCE to provide t is
complex switc ing function. T e selections
of t e two position selector switc are:
LEFT: From left plug-in or left vertical
amplifier.
RIGHT: From rig t plug-in or rig t vertical
amplifier. T e selections of t e four posi 
tion selector switc are:
Fig. 2- . Line Voltage Selector assembly; provided in instruments
with serial number 2000 and up.
2-2