Tektronix 1720/1721 Instruction Manual Instruction Manual

Instruction Manual

1720/1721
Vectorscope (S/N B060000 & Above)

070-5846-07

Warning

The servicing instructions are for use by qualified
personnel only. To avoid personal injury, do not
perform any servicing unless you are qualified to
do so. Refer to all safety summaries prior to
performing service.

www.tektronix.com

Copyright E Tektronix, Inc., 1986, 1990, 1993, 1995. All rights reserved.
Tektronix products are covered by U.S. and foreign patents, issued and
pending.

Information in this publication supersedes that in all previously published ma­terial. Specifications and price change privileges reserved. The following are
registered trademarks: TEKTRONIX and TEK.

For product related information, phone: 800-TEKWIDE (800-835-9433), ext.
TV.

For further information, contact: Tektronix, Inc., Corporate Offices, P.O. Box
1000, Wilsonville, OR 97070--1000, U.S.A. Phone: [phone]; TLX:
192825; TWX: (910) 467--8708; Cable: TEKWSGT.

WARRANTY

Tektronix warrants that this product, that it m anufactures and sells, will be free from defects in materials

and workmanshipfor a period of three (3) years from the date of shipment. Ifany such product proves defec-

tive during this warranty period, Tektronix, at its option, either will repair the defective produc t without

charge for parts and labor, or will provide a replacement in exchange for the defective product.

In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expi-

ration of the warranty period and make suitable arrangements for the performance of service. Customer
shall be responsible for packaging and shipping the defective product to the service center designated by

Tektronix, with shipping charges prepaid. Tektronix shall pay for the return of the product to Customer if

the shipment is to a location within t he country in which the Tektronix service center is located. Customer

shall be responsible for paying all shipping charges, duties, taxes, and any other charges for products re-

turned to any other locations.

This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inade-

quate maintenance and care. Tektronix shall not be obligated to furnish service under this warranty a) to

repair damage resulting from attempts by personnel other than Tektronix representative s to install, repair

or service the product; b) to repair damage resulting from improper use or connection to incompatible

equipment; c) to repair any damage or malfunction caused by the use of non-Tektronix supplies; or d) to
service a product that has been modified or integrate d with other products when the effect of such modifica-

tion or integration increases the time or difficulty of servicing the product.

THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS PRODUCT IN LIEU
OF ANY OTHER WARRANTIES, EXPRESSED OR IMPLIED. TEKTRONIX AND ITS VEN­DORS DISCLAIM ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE. TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE DE­FECTIVE PRODUCTS IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUS­TOMER FOR BREACH OF THIS W ARRANTY. TEKTRONIX AND ITS VENDORS WILL NOT
BE LIABLE FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAM­AGES IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS ADVANCE NO­TICE OF THE POSSIBILITY OF SUCH DAMAGES.

Table of Contents

Table of Contents i.......................................................

General Safety Summary viii................................................

Preface x...............................................................

Section 1 Introduction and Specification 1--1....................................

Accessories 1--2............................................................

Standard Accessories 1--2.................................................

Optional Accessories 1 --2.................................................

Options 1--2...............................................................

CRT Options 1--2........................................................

Power Cord Options 1--2..................................................

Safety Information 1--3......................................................

Specifications 1--3..........................................................

Section 2 Operating Instructions 2--1...........................................

Front-Panel Controls and Indicators 2--1.........................................

INPUT 2--2............................................................

GAIN 2--2.............................................................

PHASE 2--3............................................................

DISPLAY 2--3..........................................................

MISCELLANEOUS 2--3..................................................

Rear-Panel Connectors 2--4...................................................

BNC Connectors 2--4....................................................

Subminiature D-Type Connectors 2--5.......................................

Power Input 2--6........................................................

Miscellaneous 2--6.......................................................

Using the 1720/1721 in Auxiliary Mode 2--6.....................................

INPUT Switching 2--7....................................................

REF Switching 2--7......................................................

LINE SELECT 2--7......................................................

STORE 2--7............................................................

RECALL 2-- 7..........................................................

Measurement Applications 2--14................................................

Color Measurements 2--14.................................................

Functional Use of the Vector Graticule 2--18......................................

Measurement of Color Bars 2--18............................................

Differential Gain and Phase Measurements 2--20...............................

X Y Measurements 2--22......................................................

Making Stereo Audio Phase Measurements 2--22...............................

Looking at Incidental Carrier Phase Modulation 2--23...........................

Service Safety Summary s--1.................................................

1720/1721

Section 3 Installation 3--1.....................................................

Packaging 3--1..........................................................

Electrical Installation 3--1....................................................

i

Table of Contents

Section 4 Theory of Operation 4--1.............................................

Power Source 3--1.......................................................

Mains Frequency and Voltage Ranges 3--1....................................

Operating Options 3--1...................................................

X Y INPUT Connector 3--1...............................................

Auxiliary Connector 3--3..................................................

Mechanical Installation 3--4...................................................

Cabinetizing 3 --4........................................................

Securing the Instrument in its Cabinet 3--6...................................

Rack Mounting 3--7......................................................

Custom Installation 3--9..................................................

Overview 4--1..............................................................

Block Diagram 4--2.........................................................

Video Input 4--2.........................................................

Luminance Processing 4--2................................................

Microprocessor 4-- 2......................................................

Gain Cell 4-- 3..........................................................

Chrominance Processing 4--3..............................................

Demodulators 4--4.......................................................

Output Amplifiers 4 --4...................................................

CRT Blanking 4--4......................................................

Circuit Descriptions 4--5.....................................................

DIAGRAM 1 INPUT AND DEFLECTION AMPLIFIERS 4--5.......................

Video Input Amplifiers 4--5...............................................

Gain Cell 4-- 6..........................................................

DIAGRAM 2 SUBCARRIER REGENERATOR 4--6...............................

Reference Switch 4--7....................................................

Luminance and Chrominance Amplifiers 4--8.................................

Sync Separator 4--8......................................................

Bowes Oscillator 4--8....................................................

Back Porch Sample 4 --8..................................................

Loop Phase Detector and Amplifier 4--8.....................................

Quadrature Phase Detector and Amplifier 4--9.................................

Burst Clamp 4--9........................................................

Lock Detector and Bandwidth Switch 4--9....................................

Error Amplifier 4--9.....................................................

PAL Phasing 4--10........................................................

VCXO 4--10.............................................................

DIAGRAM 3 DEMODULATOR 4--11...........................................

V-Axis Switcher 4-- 11.....................................................

Chrominance Demodulators 4--12...........................................

Sync Tip Chrominance Clamp 4--12..........................................

Demodulator Output Filters and Amplifiers 4--12...............................

Vector Center Dot Position Clamp 4--12......................................

DIAGRAM 4 DEFLECTION AMPLIFIER 4--13...................................

XY Input Amps 4--14.....................................................

Deflection Amplifiers 4--14................................................

Center Dot Comparators 4--14..............................................

CRT Blanking 4--14......................................................

DIAGRAM 5 MICROPROCESSOR 4--15........................................

ii

1720/1721

Microprocessor 4--15......................................................

DIAGRAM 6 CONTROL CIRCUIT 4--17........................................

Z-Axis Control 4--18......................................................

Trace Rotation 4--18......................................................

Graticule Illumination 4--18................................................

Post Regulators 4--18.....................................................

DIAGRAM 7 LOW VOLTAGE POWER SUPPLY 4--19.............................

Line Rectifier and Filter 4--19..............................................

Pulse Width Modulator 4--20...............................................

Output Filters 4--21.......................................................

Error Amplifier 4--21.....................................................

Feedback Transformer Driver and Peak Detector 4--21...........................

Output HV Shutdown 4--21.................................................

DIAGRAM 8 HIGH VOLT AGE POWER SUPPLY 4--22............................

HV Osc and Error Amp 4--22...............................................

Power Supply Outputs 4--23................................................

Focus Amplifier 4--23.....................................................

Grid Drive Circuit 4--23...................................................

Z-Axis Amplifier 4--23....................................................

Section 5 Checks and Adjustments 5--1.........................................

Recommended Equipment List 5--1.............................................

Electrical Instruments 5 --1................................................

Auxiliary Equipment 5 --3.....................................................

Performance Check Procedure Short-Form Reference 5--5...........................

Performance Check Procedure 5--6.............................................

Adjustment Procedure 5--17....................................................

Signal Connections 5--18..................................................

Adjustment Procedure Short-Form Reference 5--19.................................

Long-Form Adjustment Procedure 5--20..........................................

Table of Contents

1720/1721

Section 6 Maintenance 6--1....................................................

Preventive Maintenance 6--1..................................................

Cleaning 6--1...........................................................

V isual Inspection 6-- 2....................................................

Static-Sensitive Components 6--2...........................................

Performance Checks and Readjustments 6--3..................................

Troubleshooting 6--4........................................................

Foldout Pages 6--4.......................................................

Parts Lists 6-- 5..........................................................

Major Assembly Interconnection 6--5........................................

General Troubleshooting Techniques 6--6....................................

Specific Troubleshooting Procedures 6--8........................................

Power Supply 6--8.......................................................

Troubleshooting Procedure 6--8............................................

Introduction 6--8........................................................

Low Volts Supply 6--9....................................................

High Volts Supply 6--12...................................................

Serial Port and LED Driver Diagnostics 6--14..................................

Corrective Maintenance 6--15..................................................

Obtaining Replacement Parts 6--15..........................................

Mechanical Disassembly/Assembly 6--15.........................................

iii

Table of Contents

Section 7 Options 7--1.........................................................

Bezel Removal 6--16......................................................

Graticule Light Removal and Replacement 6--17...............................

CRT Removal 6--18.......................................................

Replacement of the CRT 6--18..............................................

Removing the Rear Panel 6--19.............................................

Removing the Front Panel Circuit Board 6--19.................................

Removing the Main Board 6--20.............................................

Removing the Power Supply Board 6--22......................................

Repackaging 6--23...........................................................

Identification Tag 6--23....................................................

Repackaging for Shipment 6--23.............................................

Options 7--1...............................................................

CRT Options 7--1........................................................

Power Cord Options 7--1..................................................

Field Upgrade Kits 7--1......................................................

Cabinets 7--1...........................................................

Plain Cabinet (1700F00) 7--2..............................................

Carrying Case (1700F02) 7--2..............................................

Side-by-Side Rack Adapter (1700F05) 7--2...................................

DC Power Supply 7--2.......................................................

DC Power Supply Field Upgrade Kit (1700F10) 7--2...........................

Battery Pack (BP1) 7--2..................................................

Ordering 7--2..............................................................

Section 8 Replaceable Electrical Parts 8--1...................................

Parts Ordering Information 8--1................................................

Using the Replaceable Electrical Parts List 8--1...................................

Section 9 Diagrams/Circuit Board Illustrations 9--1.............................

Section 10 Replaceable Mechanical Parts 10--1...................................

iv

1720/1721

List of Figures

Figure 2-1: Control and indicator locations. 2--1......................................

Figure 2-2: 1720/1721 rear panel. 2--5..............................................

Figure 2-3: Signal connection for the Operator’s Checkout Procedure. 2--9.................

Figure 2-4: 1720/1721 typical vector display. 2--10.....................................

Figure 2-5: Modulated staircase waveform shown on a 1721. 2--10........................

Figure 2-6: Color bar and modulated staircase signals both displayed on a 1721. 2--11.........

Figure 2-7: Connection for using black burst signal for External Reference. 2--12.............

Figure 2-8: 1720/1721 test circle display. 2 --12........................................

Figure 2-9: NTSC standard color phase Vector diagram. 2--15............................

Figure 2-10: PAL standard color phase Vector diagram. 2--15.............................

Figure 2-11: Partial 1720 graticule showing the 75% amplitude burst target. 2--16.............

Figure 2-12: Partial 1721 graticule showing the 75% amplitude burst target. 2--17.............

Figure 2-13: Fine detail of the 1720 graticule magenta target. 2--18........................

Figure 2-14: Fine detail of the 1721 graticule target. 2--19................................

Figure 2-15: Simulated 1720 graticule showing the relationship between amplitudes on the

I and Q modulation axes and the location of the color vector targets. 2--19.........

Figure 2-16: Simulation of a 1721 graticule showing the relationship between amplitudes

on the U and V axes and the locations of the color vector targets. 2--20...........

Figure 2-17: A simulation of a part of the 1720 graticule showing the differential phase and

gain measurement scales with approximately 10° differential Phase (dP). 2--21.....

Figure 2-18: Simulation of the 1721 Differential Gain and Phase graticule showing

approximately 10% differential Gain (dG). 2--22.............................

Table of Contents

1720/1721

Figure 3-1: Plug jumper locations.. 3--2.............................................

Figure 3-2: 1720/1721 REMOTE connector pins with their functions. 3--3.................

Figure 3-3: 1720/1721 AUXILIARY connector pins with their functions. 3--4...............

Figure 3-4: 1700F00 plain cabinet. 3--5.............................................

Figure 3-5: 1700F02 portable cabinet. 3--6...........................................

Figure 3-6: Cabinet securing screws. 3--7............................................

Figure 3-7: 1700F05 rack adapter. 3--7..............................................

Figure 3-8: 1700F05 rack adapter adjustment. 3--8.....................................

Figure 3-9: 1720/1721 and 1700F06 blank panel. 3--8..................................

Figure 3-10: Typical custom installation showing the console. 3--9........................

Figure 4-1: Simple block diagram of a 1720/1721 Vectorscope. 4--3.......................

v

Table of Contents

Figure 4-2: Block diagram of the Phase Lock Loop 4--7................................

Figure 5-1: Rear view of Remote plug connections.. 5--4................................

Figure 5-2: Loop--through connection of black burst signal to both EXT REF and CH-B. 5--7..

Figure 5-3: Using the vector graticule --3 dB markings to measure bandwidth. 5--8...........

Figure 5-4: Signal connection for checking CH-A/CH-B phase matching. 5--10...............

Figure 5-5: Rear-panel XY INPUT connector showing inputs.. 5--14.......................

Figure 5-6: Audio frequency XY display. 5--15........................................

Figure 5-7: Adjustment and test point locations for 1720/1721 Vectorscope. 5--17.............

Figure 5-8: Starting connections for the adjustment procedure. 5--18.......................

Figure 5-9: Test points and adjustment locations for the ¦11.8V supplies. 5--21..............

Figure 6-1: Circuit board assembly locations 6--5.....................................

Figure 6-2: Multiple pin connectors used in the 1720/1721 Waveform Monitors 6--6..........

Figure 6-3: Screws that need to be removed to remove the bezel. 6--17......................

Figure 6-4: Screws that need to be removed to remove the rear panel 6--19..................

Figure 6-5: Screws that hold the Front Panel circuit board (A2) in place. 6--20...............

Figure 6-6: Screws holding the main circuit board (A3) in place. 6--21......................

Figure 6-7: Screws holding the Power Supply circuit board (A1) in place. 6--22..............

Figure 6-8: Repackaging 6--23.....................................................

vi

1720/1721

List of Tables

Table 1--1: Signal Input 1--4..................................................

Table 1--2: Vector Mode 1--5..................................................

Table 1--3: XY Mode 1--7....................................................

Table 1--4: CRT Display 1--7..................................................

Table 1--5: Power Source 1--8.................................................

Table 1--6: Environmental Characteristics 1--8....................................

Table 1--7: Certification 1-- 9..................................................

Table 1--8: Physical Characteristics 1--9.........................................

Table 3--1: Internal Jumper Selection 3--2.......................................

Table 3--2: AUXILIARY Connector Pin Assignments 3--4..........................

Table 4--1: U613 Switching Control Outputs 4--16..................................

Table 5--1: Performance Check Procedure Short-Form Refe rence 5--5.................

Table 5--2: Adjustment Procedure Short-Form Reference 5--19........................

Table of Contents

Table 6--1: Static Susceptibility 6 --2............................................

Table 6--2: Power Supply Fault Symptoms 6--9...................................

Table 6--3: Low Volts Supply Voltages 6--9......................................

Table 6--4: Control Circuit Test Points 6--11......................................

Table 6--5: High Volts Supply Fault Symptoms 6--12................................

Table 6--6: High Voltage Oscillator Test Points 6--13................................

1720/1721

vii

General Safety Summary

Review the following safety precautions to avoid injury and prevent damage to
this product or any products connected to it. To avoid potential hazards, use this
product only as specified.

Only qualified personnel should perform service procedures.

ToAvoidFireor

Personal Injury

Use Proper Power Cord. Use only the power cord specified for this product and
certified for the country of use.

Connect and Disconnect Properly. Do not connect or disconnect probes or test
leads while they are connected to a voltage source.

Ground the Product. This product is grounded through the grounding conductor
of the power cord. To avoid electric shock, the grounding conductor must be
connected to earth ground. Before making connections to the input or output
terminals of the product, ensure that the product is properly grounded.

Observe All Terminal Ratings. To avoid fire or shock hazard, observe all ratings
and markings on the product. Consult the product manual for further ratings
information before making connections to the product.

Do not apply a potential to any terminal, including the common terminal, that
exceeds the maximum rating of that terminal.

Do Not Operate Without Covers. Do not operate this product with covers or panels
removed.

Avoid Exposed Circuitry. Do not touch exposed connections and components
when power is present.

Do Not Operate With Suspected Failures. If you suspect there is damage to this
product, have it inspected by qualified service personnel.

viii

Do Not Operate in Wet/Damp Conditions.

Do Not Operate in an Explosive Atmosphere.

Keep Product Surfaces Clean and Dry.

Provide Proper Ventilation. Refer to the manual’s installation instructions for

details on installing the product so it has proper ventilation.

1720/1721

General Safety Summary

Symbols and Terms

Terms in this Manual. These terms may appear in this manual:

WARNING. Warning statements identify conditions or practices that could result
in injury or loss of life.

CAUTION. Caution statements identify conditions or practices that could result in
damage to this product or other property.

Terms on the Product. These terms may appear on the product:

DANGER indicates an injury hazard immediately accessible as you read the
marking.

WARNING indicates an injury hazard not immediately accessible as you read the
marking.

CAUTION indicates a hazard to property including the product.

Symbols on the Product. The following symbols may appear on the product:

CAUTION

Refer to Manual

WARNING

High Voltage

Double

Insulated

Protective Ground

(Earth) Terminal

Not suitable for

connection to

the public telecom-

munications network

1720/1721

ix

Preface

This manual documents the TEKTRONIX 1720/1721 Vectorscope. Information
that applies to all instruments in the series refers to the 1720/1721. Information
that applies to only specific instruments within the series refers to the model
numbers of those instruments (i.e., 1720, 1721).

The information in this manual is intended for instrument operators and service
technicians. Operators are assumed to be familiar with basic television terms and
measurements. Qualified service technicians are also assumed to be familiar with
television terms and measurements, and have moderate experience with analog
and logic circuits.

Section 1, Introduction and Specification, includes a general description of the
instrument followed by the Specifications. The Specifications include references
to the corresponding Performance check steps.

Section 2, Operating Instructions, familiarizes the user with the front-- and
rear-- panel controls, connectors, and indicators; includes an operator’s checkout
procedure; and includes other operator familiarization information.

Section 3, Installation, includes electrical and mechanical installation informa­tion. The electrical installation information includes adjustments and operational
changes available with the instrument. The mechanical installation information
includes rackmounting, custom installation, and portable use.

Section 4, Theory of Operation, provides an overall block diagram description
and detailed circuit descriptions. Read the block diagram description for an
overview of the instrument. The detailed circuit descriptions should be used
with the block diagram and schematic diagrams in the foldout pages for specific
information about individual circuits.

Section 5, Checks and Adjustments, includes the Performance Check
Procedure and the Adjustment Procedure. The Performance Check Procedure is
used to verify that the instrument’s performance is within its specifications, and
the Adjustment Procedure is used to adjust the instrument to meet its specifica­tions. The procedures are preceded by a list of recommended test equipment.
Each procedure has a short form listing of the individual steps.

Section 6, Maintenance, includes preventive, troubleshooting, and corrective
information.

Section 7, Options, contains summaries of available instrument options.
Additional information concerning options is included in appropriate places
throughout the manual.

Section 8, Replaceable Electrical Parts, includes ordering information and part
numbers for all replaceable electrical parts.

x

Preface

Section 9, Diagrams, contains servicing illustrations. These include adjustment
locations, circuit board part locations, a block diagram, schematic diagrams, and
waveforms. Parts locating tables are included that cross--reference the circuit
board illustrations and the schematic diagrams.

Section 10, Replaceable Mechanical Parts, includes ordering information and
part numbers for all replaceable mechanical parts. This parts list is referenced to
an exploded view mechanical drawing. Also included are lists of standard and
optional accessories.

xi

Preface

xii

Introduction and Specifications

Section 1 Introduction and Specifications

The TEKTRONIX 1720/1721 is an 8-1/2”--wide by 5-1/4”--high Vectorscope,
weighing 8-1/2 pounds. Both the 1720 (System M, NTSC) and the 1721
(System I, B, etc., PAL) versions can be powered from an ac source or, with the
addition of a field upgrade kit (1700F10), from 12 Vdc. The crt occupies
approximately two-thirds of the front-panel area, with the control panel taking up
the remainder of the space. Operation is controlled by a Microprocessor that
polls the front-panel switches. Front-panel switches are momentary-touch type
with lighted functional indicators. Some of the switches are also used to select
special functions, which are accessed by holding the switches in until the
Microprocessor recognizes the request.

The signal is displayed on a bright crt capable of displaying one line per frame.
It is of the mesh-type, for better geometry, and uses an internal graticule to
reduce parallax. Variable graticule scale illumination provides even lighting over
the usable graticule area without hot spots or voids, to improve measurement
accuracy and the quality of display pictures. Option 74 provides a P4 (white)
phosphor tube.

Composite video signals, for the Channel A and B Inputs and the External
Reference Signal Input, are brought in through high impedance bridging
loop-throughs, in order to protect the integrity of the signal paths. The input
switching allows for the display of Channel A, Channel B, or both inputs.
Synchronization can be either internal or external.

The 1720/1721 offers a choice of individual displays of vectors or XY or both.
The XY display, with accompanying graticule scale, allows this vectorscope to
be used for stereo audio monitoring. In addition to the usual color bar amplitude
and phase relationships, the vector display can also be used to make differential
gain and phase measurements. The 1721 has the +V display that is used to
check PAL system color encoders. Full 360° phase shift and a test circle are also
included in these vectorscopes.

Stereo audio input for XY display is balanced line through the rear-panel
REMOTE connector.

The 1720/1721, through the Auxiliary function, reacts to Store and Recall
commands from a companion 1730-Series Waveform Monitor, when the two are
interconnected. This provides for storing of up to four front-panel setups that
can be recalled when the Waveform Monitor Recall button is pressed, or a valid
1730-Series Remote ground closure occurs. The Auxiliary function can also take
advantage of the blanking strobe, from the waveform monitor, to unblank the
vectorscope crt for a line select display.

1720/1721

1- 1

Introduction and Specifications

Accessories

Standard Accessories

The 1720/1721 is shipped with a set of accessories that are needed for its
installation or day-to-day operation. These are the “Standard Accessories.”
They are physically packaged in a small, cardboard carton within the packing
box.

In addition to the Standard Accessories, there are other accessory items that can
be purchased from Tektronix, Inc., which will either enhance operation or help to
customize the installation. The following list of accessories is divided into these
two categories. Part numbers for the standard accessories can be found at the
end of the Replaceable Mechanical Parts list.

1 1720/1721 Instruction Manual.

1 Power Cable Assembly.

Optional Accessories

Options

CRT Options

1 Spare Cartridge Fuse (3AG 2A, 250 V, Fast Blow).

3 Replacement Scale Illumination Bulbs (Tektronix P/N 150--0168--00 or

ANSI #73).

1 Auxiliary Control Cable, for use with a 1730-Series Waveform Monitor.

1700F00, Plain Cabinet (painted silver grey)

1700F02, Portable Cabinet (painted silver grey)

1700F05, Side-by-Side Rack Adapter

1700F06, Blank Half-Rack-Width Panel

Standard instruments are shipped with a P31 (green) phosphor crt installed.
Option 74 instruments are shipped with a P4 (white) phosphor crt installed.

Power Cord Options

1- 2

Any of the power cord options described in Section 7 can be ordered for the
1720/1721. If no power cord option is ordered, instruments are shipped with a
North American 125 V power cord and one replacement fuse.

1720/1721

Safety Information

Specifications

Introduction and Specifications

1720/1721 instruments are intended to operate from an ac power source that will
not apply more than 250 V rms between the supply conductors or between either
supply conductor and ground. A protective ground connection by way of the
grounding conductor is essential for safe operation.

The 1720/1721 was tested for compliance in a cabinet. To ensure continued
compliance, the instrument will need to be enclosed in a cabinet that is equiva­lent to the Factory Upgrade Kits that are listed as Optional Accessories for the
1720/1721. Drawings of the available cabinets are contained in the Installation
Instructions (Section 3).

The Performance Requirements listed here apply over an ambient operating
temperature range of 0 to 50° C and are valid only when the instrument is
calibrated at 25°±5° C, following a minimum warm-up period of 20 minutes.

Procedure and the list of test equipment required to verify Performance
Requirements are located in Section 5.

1720/1721

1- 3

Introduction and Specifications

Table 1- 1: Signal input

Characteristics Performance requirement Supplemental information

Step
number

Return loss (75Ω)

Video inputs (CH A, CH B)
EXT REF

Atleast40dBfrom50kHzto6MHz. Loop-through terminated in 75W. Input

in use or not in use, instrument power
on or off, all deflection factor settings.

Crosstalk between channels Greater than 70 dB of isolation be-

tween channels. Measured at F

SC

between Channel A, Channel B, and
EXT REF.

Loop-through isolation Greater than 70 dB of isolation be-

tween loop-throughs. Measured at F
between Channel A, Channel B, and
EXT REF.

Input requirements Stable display with composite video, or

black burst with 286 mV (300 mV PAL)
burst ±6dB.

DC input impedance (unterminated) Greater than 15 kΩ

EXT REF input Composite video (can be CW subcarr-

ier if two internal jumpers are moved).

Absolute maximum input voltage ±12 VDC plus peak AC

Maximum operating input voltage Peak AC + DC should be within

+8.0 V and --5.6 V for proper operation.

11

SC

3

Table 1- 2: Vector mode

Characteristic Performance requirement Supplemental information

Chrominance processing characteris­tics

Nominal subcarrier frequency (F

NTSC
PAL

)

sc

3.579545 MHz.

4.43361875 MHz.

Chrominance bandwidth

Upper --3 dB point
Lower --3 dB point

Fsc+500 kHz, ±100 kHz
F

--500 kHz, ±100 kHz

sc

Display

Vector phase accuracy
Vector gain accuracy
Quadrature phasing

±1.25 Measured with color bar signal

Typically, ±2.5%
Typically, ±0.5°

1- 4

Step
number

4

5
5

1720/1721

Table 1- 2: Vector mode (cont.)

Characteristic

Introduction and Specifications

Step

Supplemental informationPerformance requirement

number

Subcarrier regenerator

NTSC pull --in range
PAL pull--in range

Pull--in time

Phase shift with subcarrier freq­ency change (NTSC)
Phase shift with subcarrier freq­uency change (PAL)

Phase shift with burst amplitude
change

Phase shift with input channel
change

Phase shift with VAR GAIN control

±50 Hz of F
±10 Hz of F

sc
sc

±2° from Fscto (Fsc+ 50 Hz) or Fscto
(F

-- 50 Hz)

sc

±2° from F
(F

-- 10 Hz)

sc

to (Fsc+ 10 Hz) or Fscto

sc

±2° from nominal burst amplitude to
±6dB.

±0.5°

±1° as gain varies from 3 dB to --6 dB.

Subcarrier regenerator freeruns in
absence of appropriate signal.
Reference can be burst of either
displayed signal or external reference
signal.

PAL units are tested to 10 Hz, but
typically lock to within 50 Hz.

Within 1 second, with subcarrier
frequency within 50 Hz (10 Hz for PAL)
od F

.

sc

With EXT REF selected.

6

6

6

6

7

7

Phase control range

Burst jitter

Display characteristics

Differential phase
Differential gain

Position control range, horizontal
Position control range, vertical

Clamp stability

Variable GAIN range

1720/1721

<0.5°

±1°
±1%

At least .25” (6 mm) from center.
At least .25” (6 mm) from center.

0.0156” (0.4 mm) or less.

+14 dB to --6 dB of 75% color bar
preset gain.

360° continuous rotation.

With 140 IRE (1 V PAL) composite
video input. INT or EXT referenced.

Measured with 140 IRE (1 V PAL)
linearity signal (5 step, 10 step, or
ramp) with 40 IRE (300 mV PAL) of
subcarrier.

Center spot movement with PHASE
control rotation.

+5 to --0.5 amplitude.

7

8

9

9

10

1- 5

Introduction and Specifications

Table 1- 3: XY Mode

Characteristic Performance requirement Supplemental information

Input DC Coupled differential inputs through

rear-panel REMOTE connector.

Input amplitude 2to9V

Maximum input voltage ±15 V peak signal plus DC.

Frequency response

p--p

DC to greater than 500 kHz.

Adjustable full scale deflection 0 dBm
to +12 dBm for 600Ω system. Factory
set to 0 dBm. Specification verified
during calibration.

3 dB point.

Step
number

14

High gain mode

X and Y input phase matching Less than a trace width of separation

DC to greater than 100 kHz.

at 20 kHz.

3 dB point. Not a differential input,
minus inputs must be grounded.

Single ended. Phase matching may be
improved, above 20 kHz, by adjusting
C484.

Table 1- 4: CRT Display

Characteristic Performance requirement Supplemental information

CRT viewing area 80 X 100 mm.

Accelerating Potential 15.75 kV

Trace rotation range Greater than ±1° from horizontal. Total adjustment range i s typi cally 8°. 12

Graticule Internal vector, variable scale illumina-

tion.

14

13

Step
number

Table 1- 5: Power source

Characteristic Performance requirement Supplemental information

Mains voltage ranges 90 -- 250 V. Continuous range from 90 to 250 VAC. 2

Mains frequency range 48 -- 66 Hz.

Power consumption 0.7 A maximum, 0.35 A (21.4 Watts)

typical.

1- 6

Step
number

1720/1721

Introduction and Specifications

Table 1- 6: Environmental Characteristics

Characteristic Supplemental information

Temperature

Non-operating
Operating

Altitude

Non-operating
Operating

Vibration -- operating 15 minutes each axis at 0.015 inch, frequency varied from

Shock -- non-operating 30 g’s, 1/2 sine, 11 ms duration, 3 shocks per surface (18 total).

Transportation Qualified under NTSC Test Procedure 1A, Category II (30--inch

Humidity Will operate at 95% relative humidity for up to five days. Do not

-- 5 5 t o + 7 5 °C
0to+50°C

To 50,000 feet
To 15,000 feet

10-55-10 Hz in 1-minute cycles wi th instrument secured to
vibration platform. Ten minutes each axis at any resonant point or
at 55 Hz if no resonant point is found.

drop).

operate with visible moisture on the circuit boards

Table 1- 7: Physical Characteristics

Characteristic Supplemental information

Dimensions

Height
Width
Length

Weight 8.5 lbs (3.8 kg).

5.25 inches (133.4 mm).

8.5 inches (215.9 mm)

10.125 inches (460.4 mm)

Table 1- 8: Certifications and Compliances

Category Standards or description

EC Declaration of Conformity -­EMC

Meets intent of Directive 89/336/EEC for Electromagnetic Compatibility. Compliance was
demonstrated to the following specifications as listed in the Official Journal of the European Union:

EN 50081-1 Emissions:

EN 55022 Class B Radiated and Conducted Emissions

EN 50082-1 Immunity:

IEC 801-2 Electrostatic Discharge Immunity
IEC 801-3 RF Electromagnetic Field Immunity
IEC 801-4 Electrical Fast Transient/Burst Immunity

1720/1721

1- 7

Introduction and Specifications

Table 1- 8: Certifications and Compliances (cont.)

Category Standards or description

Australia/New Zealand
Declaration of Conformity -- EMC

FCC Compliance Emissions comply with FCC Code of Federal Regulations 47, Part 15, Subpart B, Class A Limits.

Installation (Overvoltage)
Category

Pollution Degree A measure of the contaminates that could occur in the environment around and within a product.

EC Declaration of Conformity -­Low Voltage

U.S. Nationally Recognized
Testing Laboratory Listing

Canadian Certification CAN/CSA C22.2 No. 231 CSA safety requirements for electrical and electronic measuring and

Additional Compliance IEC61010-1 Safety requirements for electrical equipment for measurement,

Installation (Overvoltage)
Category

Pollution Degree Pollution Degree 2 As defined in IEC 1010--1. Rated for indoor use only.

Safety Certification Compliance Temperature, operating: 0 to 50° C.

Altitude (maximum operating) 2,000 meters.

Equipment Type Test and measuring.

Safety Class Class I (as defined in IEC 1010--1, Annex H) -- grounded product.

Complies with EMC provision of Radiocommunications Act per the following standard(s):

AS/NZS 2064.1/2 Industrial, Scientific, and Medical Equipment: 1992

AS/NZS 3548 Information Technology Equipment: 1995

Terminals on this product may have di ff erent installation (overvoltage) category designations. The
installation categories are:

CAT III Distribution-level mains (usually permanently connected). Equipment at this level is

typically in a fixed industrial location.

CAT II Local-level mains (wall sockets). Equipment at this level includes appl iances, portable

tools, and similar products. Equipment is usually cord-connected.

CAT I Secondary (signal level) or battery operated circuits of electronic equipment.

Typically the internal environment inside a product i s considered to be the same as the external.
Products should be used only in the environment for which they are rated.

Pollution Degree 2 Normally only dry, nonconductive pollution occurs. Occasionally a

temporary conductivity that is caused by condensation must be
expected. This location is a typical office/home environment.
Temporary condensation occurs only when the product is out of
service.

Compliance was demonstrated to the fol lowing specification as listed in the Official Journal of the
European Union:

Low Voltage Directive 73/23/EEC, amended by 93/68/EEC

EN 61010-1 Safety requirements for electrical equipment for measurement

control and laboratory use.

UL1244 Standard for electrical and electronic measuring and testing

equipment.

test equipment.

control, and laboratory use.

CAT II As defined in IEC 1010--1, Annex J.

1- 8

1720/1721

Operating Instructions

Section 2 Operating Instructions

These instructions provide information about the front-panel controls, rear-panel
connectors, the Operator’s Familiarization/Checkout Procedures, and discussions
about vector and audio measurements using the 1720/1721.

Front-Panel Controls and Indicators

The front-panel controls and indicators consist of momentary contact push-but­ton switches, variable controls, and backlit switch selections. See Figure 2-1 for
the control and indicator locations.

RO TATE

GAIN

CAL

1

MODE

VECT

XY

BOTH

VARIABLE BARS

4

6

FOCUS SCALE INTENS

8
9

AUXILIARY

2 3

ON

PAL

+V

ON

REF

INT

EXT

TEST

172X

PHASE

DISPLAY

POWER

VECTOR

SCOPE

INPUT

CH--A

CH--B

BOTH

GAIN

75%

100%

5

7

10

ON

13

14

15 16

Figure 2-1: Control and indicator locations.

1720/1721

= HOLD FOR FUNCTION

11

12

2- 1

Operating Instructions

There are three push-button switches, located in the INPUT block, that have an
extra function. The extra function is accessed by holding the switch down for
approximately one second. The operating selection reverts to the top of the
listed functions when the push button is repushed to exit this extra function, with
the exception of TEST, which reverts to its original state when exiting.

INPUT

1. MODE

A momentary push-button switch that toggles between the vector and XY
displays. These two functions have back lighted nomenclature with rectangular
indicators.

Holding this button in switches the MODE to a display of both vector and XY
modes. In this mode both the VECT and XY nomenclature and rectangular
indicators light up to indicate that the 1720/1721 has been switched to this mode
of operation.

GAIN

2. REF

A momentary push-button switch that toggles between INT and EXT sync
references. These two functions have back lighted nomenclature with rectangu­lar indicators.

Holding this button in switches the REF to an unlocked display of subcarrier and
enables the V-axis switcher, if a signal containing a subcarrier reference signal is
applied to the selected input. TEST nomenclature, framed by a blue box, lights
up when the 1720/1721 is switched to this mode.

3. CH--A CH--B

Momentary contact push-button switch that toggles the input between Channels
A and B. Back lighted nomenclature, with rectangular indicators, light to show
which is selected for display.

Holding this button in switches the INPUT to a display of both A and B Inputs.
This display requires an external sync reference. Both the CH-A and CH-B
indicators light when the 1720/1721 has been switched to this dual input mode.

4. VA R IA BL E

2- 2

A momentary contact push-button switch that toggles between VARIABLE gain
ON and off. The VARIABLE control adjusts amplifier input gain so that any
input signal between 0.5 V and 2.0 V peak-to-peak can be displayed. Control
has no detent, action is continuous. Back lighted nomenclature, with rectangular
indicators, lights up red to indicate that display gain is uncalibrated.

1720/1721