Tektronix 1740A Series User manual

Service Manual
1740A Series, 1750A Series, & 1760 Series
Waveform/Vector Monitors
S/N B020000 and Above
070-8469-03
This document applies to firmware version 2.00
and above.
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 ©Tektronix, Inc. All rights reserved.
Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes
that in all previously published material. Specifications and price change privileges reserved.
Tektronix, Inc., P.O. Box 500, Beaverton, OR 97077
TEKTRONIX and TEK are registered trademarks of Tektronix, Inc.

WARRANTY
Tektronix warrants that the products that it manufactures and sells will be free from defects in materials and
workmanship for a period of three (3) years from the date of shipment. If a product proves defective during this
warranty period, Tektronix, at its option, either will repair the defective product 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 expiration
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 the 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 returned to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inadequate
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 representatives 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 integrated with other products when the effect of such modification or integration increases the time
or difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER WARRANTIES, EXPRESS
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 WARRANTY.
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.

1740A Series, 1750A Series, & 1760 Series Service Manual i
Table of Contents
General Safety Summary ix...................................
Service Safety Summary xi....................................
Preface xiii...................................................
Contacting Tektronix xiv.............................................
Specifications
Product Description 1--1..............................................
Input Format 1--13....................................................
Installation 2--1.....................................................
Standard Accessories 2--1.............................................
Mechanical Installation 2--2...........................................
Electrical Installation 2--8.............................................
Rear Panel Connectors 2--9............................................
Remote Connector 2--10...............................................
Remote Connector Converter 2--12.......................................
RS232 Connector 2--13................................................
Installing Software 2--14...............................................
Loading Software 2--16................................................
Calibrating New Features 2--20..........................................
Special Recovery for Power Loss During the Execution of UPGRADE 2--20.....
Operating Information
Getting Started 2--23..................................................
Operating Instructions 2--24............................................
General Menu Information 2--25.........................................
Functional Overview 2--27.............................................
Displaying a Signal 2--29...............................................
Theory of Operation
Block Diagram Description 3--1..................................
Block Diagram 1: Input and Waveform Monitor 3--1........................
Block Diagram 2: Vector -- SCH -- Component 3--3.........................
Block Diagram 3: Microprocessor and Line Rate Controller 3--5..............
Circuit Theory 3--7............................................
Diagrams <1> and <2> Channel A and Channel B Inputs 3--7...............
Diagram <3> Vertical Input 3--8........................................
Diagram <4> Vertical Output 3--10.......................................
Diagram <5> Horizontal 3--11..........................................
Diagram <6> Microprocessor 3--12......................................
Diagram <7> Dynamic Control 3--14.....................................
Diagram <8> Readout 3--15............................................
Diagram <9> DACS & Serial 3--16......................................
Diagram <10> Remote & 1760 Series / XROM Bus Connectors 3--16...........

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ii 1740A Series, 1750A Series, & 1760 Series Service Manual
Diagram <11> Z-Axis & Control 3--17....................................
Diagram <12> Front Panel 3--18.........................................
Diagram <13> DACs & Digital Control 3--18..............................
Diagram <14> Subcarrier Regenerator 3--19...............................
Diagram <15> Phase Shifter 3--21.......................................
Diagram <16> Demodulator 3--22.......................................
Diagram <17> Internal SCH 3--23.......................................
Diagram <18> Reference SCH 3--26.....................................
Diagram <19> Component Inputs, Transcoders, & RGB Outputs 3--28..........
Diagram <20> Component Control and Switching (1760 Series Only) 3--30......
Diagram <21> Low Voltage Power Supply 3--32............................
Diagram <22> High Volts Power Supply 3--35..............................
Performance Verification
Recommended Equipment List 4--1.....................................
Performance Check Procedure Short-Form Reference 4--6...................
Performance Check Procedure 4--19......................................
Adjustments
Required Equipment 5--1..............................................
Initial Setup 5--9....................................................
Functional Description of PC Display 5--10................................
Circuit Board Adjustment Locations 5--12.................................
Waveform Illustrations 5--15............................................
Maintenance
Preventing ESD 6--1.................................................
Preventive Maintenance 6--1...........................................
Performance Checks and Adjustments 6--2................................
Inspection and Cleaning 6--2...........................................
Replacing the Line Fuse 6--5...........................................
Troubleshooting 6--5.................................................
Corrective Maintenance 6--12....................................
Circuit Boards 6--12...................................................
Mechanical Disassembly/Assembly 6--13..................................
Removing the Bezel 6--13..........................................
Replacing the Graticule Light 6--14...................................
Removing the CRT 6--16...........................................
Removing the Rear Panel 6--19......................................
Removing the Front Panel and the Front Panel Circuit Board 6--21..........
Removing the Main Board 6--22.....................................
Removing the Power Supply Board 6--24..............................
Removing the Vector Board 6--25....................................
Removing the SCH Board
(1750A Series & 1760 Series Option SC only) 6--26..............
Removing the Component Board
(1760 Series only) 6--26.....................................
Repackaging 6--27....................................................

Table of Contents
1740A Series, 1750A Series, & 1760 Series Service Manual iii
Options and Accessories
Options 7--1........................................................
Standard Accessories 7--1.............................................
Optional Accessories 7--2.............................................
Replaceable Electrical Parts
Parts Ordering Information 8--1.........................................
Using the Replaceable Electrical Parts List 8--1............................
Diagrams/Circuit Board Illustrations
Replaceable Mechanical Parts
Parts Ordering Information 10--1.........................................
Using the Replaceable Mechanical Parts List 10--1..........................
Glossary
Index

Table of Contents
iv 1740A Series, 1750A Series, & 1760 Series Service Manual
List of Figures
Figure 2--1: Dimensions of the 1700F00 plain cabinet 2--2............
Figure 2--2: 1700F02 portable cabinet 2--3.........................
Figure 2--3: Rear view showing the securing screws 2--4.............
Figure 2--4: The WFM7F05 side-by-side rack adapter 2--5...........
Figure 2--5: A WFM7F05 with a blank front panel (1700F06) 2--5.....
Figure 2--6: WFM7F05 rack mount cabinet with a 1700F07 utility
drawer 2--6...............................................
Figure 2--7: Custom installation of an instrument 2--7...............
Figure 2--8: Rear panel connectors 2--9............................
Figure 2--9: Rear panel REMOTE connector. 2--10...................
Figure 2--10: Replacement adapter for 1740/1750 2--12...............
Figure 2--11: Rear panel RS232 connector 2--13.....................
Figure 2--12: Standard and alternate hookups for the 9-pin
connector 2--16.............................................
Figure 2--13: Standard and alternate hookups for 25-Pin PC
Connector 2--17.............................................
Figure 2--14: 1760 front panel 2--24................................
Figure 2--15: The CRT menu, with the bezel controls and buttons 2--25.
Figure 3--1: NTSC line count (U24) & color frame 1 SCH field pulse 3--26
Figure 3--2: PAL line count (U24) & color frame 1 SCH field pulse 3--27
Figure 3--3: Pinout of the CRT socket 3--35.........................
Figure 4--1: External Horizontal or RGB/YRGB Cable Adapter 4--4...
Figure 4--2: Remote Sync Cable Adapter 4--5......................
Figure 4--3: Audio and Timecode Cable Adapter 4--5................
Figure 4--4: Timing Cursor Check 4--16............................
Figure 4--5: Fast DC Restorer Response 4--24.......................
Figure 4--6: R--Y Display 4--27....................................
Figure 4--7: Audio Display 4--33..................................
Figure 4--8: Option Blanking Pulse 4--36...........................
Figure 4--9: Bowtie Common Mode Rejection Ratio 4--38.............
Figure 5--1: External horizontal/RGB and YRGB cable adapter 5--5...
Figure 5--2: Remote sync cable adapter 5--5........................
Figure 5--3: Audio and Timecode Cable Adapter 5--6................

Table of Contents
1740A Series, 1750A Series, & 1760 Series Service Manual v
Figure 5--4: RS232 cable standard and alternate connections for
9-pin PC connector 5--7.....................................
Figure 5--5: RS232 cable standard and alternate hookups for
25-pin PC connector 5--8....................................
Figure 5--6: Typical adjustment procedures PC screen display 5--10....
Figure 5--7: A1 Power Supply board 5--12..........................
Figure 5--8: A3 Main board 5--12..................................
Figure 5--9: A5 Vector board 5--13.................................
Figure 5--10: A6 SCH board 5--13.................................
Figure 5--11: A7 Component board 5--14...........................
Figure 5--12: Adjusting for thinnest luminance step 5--15.............
Figure 5--13: Matching flat and luminance filter responses 5--15.......
Figure 5--14: Adjusting the NTSC SCH on the oscilloscope 5--16.......
Figure 5--15: Matching the SCH dot flipping points 5--16.............
Figure 5--16: Adjusting the option blanking pulse 5--17...............
Figure 5--17: Adjusting for minimum Bowtie amplitude 5--17..........
Figure 5--18: Adjusting Diamond display phase 5--18.................
Figure 6--1: Instrument etched circuit board assemblies 6--12..........
Figure 6--2: Removing the CRT bezel 6--13.........................
Figure 6--3: Replacing graticule light bulbs 6--15....................
Figure 6--4: Removing the CRT 6--17..............................
Figure 6--5: Removing the rear panel and Input/BNC assembly 6--20...
Figure 6--6: Disassembling Input/BNC assembly A4/A4--A1 6--20.......
Figure 6--7: Removing the front--panel assembly 6--21................
Figure 6--8: Front Panel circuit board assembly 6--22.................
Figure 6--9: Screws holding the Main circuit board in place 6--23.......
Figure 6--10: Securing screws for the Power Supply circuit 6--24.......
Figure 6--11: Mounting hardware for the Vector and SCH circuit
boards 6--25................................................
Figure 6--12: Component circuit board mounting hardware 6--26......
Figure 6--13: Repackaging a 1740A, 1750A, or 1760 Series
instrument 6--27............................................
Figure 10--1: Exploded View 10--11.................................

Table of Contents
vi 1740A Series, 1750A Series, & 1760 Series Service Manual
List of Tables
Table 1--1: Waveform vertical deflection 1--3......................
Table 1--2: External reference 1--6..............................
Table 1--3: Waveform horizontal deflection 1--6...................
Table 1--4: Measurement cursors 1--7............................
Table 1--5: RGB/YRGB 1--7....................................
T a b l e 1 -- 6 : C a l i b r a t o r 1 -- 8.....................................
Table 1--7: Vector mode 1--8....................................
Table 1--8: Audio mode 1--9.....................................
Table 1--9: Time code 1--10......................................
Table 1--10: SCH Phase mode (1750 Series and
1760 Option SC Only) 1--10..................................
Table 1--11: Component vector mode (1760 Series Only) 1--12.........
Table 1--12: Lightning mode (1760 Series only) 1--12.................
Table 1--13: Bowtie mode (1760 Series only) 1--13...................
Table 1--14: Transcoded GBR outputs 1--13........................
Table 1--15: CRT display 1--14...................................
Table 1--16: Power source 1--14...................................
Table 1--17: Environmental characteristics 1--14....................
Table 1--18: Physical characteristics 1--15..........................
Table 1--19: Certifications and compliances 1--16....................
Table 2--1: Remote connector 2--11................................
Table 2--2: The available display modes 2--27.......................
Table 3--1: Transcoder signal mixing 3--28.........................
Table 3--2: Component display output switching 3--29...............
Table 4--1: Short-Form Performance Check 4--6....................
Table 4--2: Vector cursor readout values 4--17......................
Table 4--3: Audio and Timecode Values 4--32.......................
Table 6--1: External inspection check list 6--3......................
Table 6--2: Power supply fault symptoms 6--6......................
Table 6--3: Low volts supply voltages 6--6.........................
Table 6--4: Control Circuit Test Points 6--8........................
Table 6--5: Shut down logic levels 6--9............................

Table of Contents
1740A Series, 1750A Series, & 1760 Series Service Manual vii
Table 6--6: High Volts Supply Fault Symptoms 6--10.................
Table 6--7: High voltage oscillator test points 6--11..................
Table 6--8: Main Board Plug Connections 6--22.....................
Table 7--1: Power cord identification 7--2.........................

Table of Contents
viii 1740A Series, 1750A Series, & 1760 Series Service Manual

1740A Series, 1750A Series, & 1760 Series Service Manual ix
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.
Use Proper Power Cord. Use only the power cord specified for this product and
certified for the country of use.
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.
Use Proper Fuse. Use only the fuse type and rating specified for this product.
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.
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.
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.
ToAvoidFireor
Personal Injury
Symbols and Terms

General Safety Summary
x1740A Series, 1750A Series, & 1760 Series Service Manual
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
Protective Ground
(Earth) Terminal

1740A Series, 1750A Series, & 1760 Series Service Manual xi
Service Safety Summary
Only qualified personnel should perform service procedures. Read this Service
Safety Summary and the General Safety Summary before performing any service
procedures.
Do Not Service Alone. Do not perform internal service or adjustments of this
product unless another person capable of rendering first aid and resuscitation is
present.
Disconnect Power. To avoid electric shock, switch off the instrument power, then
disconnect the power cord from the mains power.
Use Caution When Servicing the CRT. To avoid electric shock or injury, use
extreme caution when handling the CRT. Only qualified personnel familiar with
CRT servicing procedures and precautions should remove or install the CRT.
CRTs retain hazardous voltages for long periods of time after power is turned off.
Before attempting any servicing, discharge the CRT by shorting the anode to
chassis ground. When discharging the CRT, connect the discharge path to ground
and then the anode. Rough handling may cause the CRT to implode. Do not nick
or scratch the glass or subject it to undue pressure when removing or installing it.
When handling the CRT, wear safety goggles and heavy gloves for protection.
Use Care When Servicing With Power On. Dangerous voltages or currents may
exist in this product. Disconnect power, remove battery (if applicable), and
disconnect test leads before removing protective panels, soldering, or replacing
components.
To avoid electric shock, do not touch exposed connections.
X-Radiation. To avoid x-radiation exposure, do not modify or otherwise alter the
high-voltage circuitry or the CRT enclosure. X-ray emissions generated within
this product have been sufficiently shielded.

Service Safety Summary
xii 1740A Series, 1750A Series, & 1760 Series Service Manual

1740A Series, 1750A Series, & 1760 Series Service Manual xiii
Preface
This manual provides servicing information for the 1740A/1750A/1760--Series
of instruments. The 1750A is identical to the 1740A, except that the 1750A--Se-
ries makes SCH Phase measurements. The 1760-Series adds component analog
measurement capability to the basic 1740A-Series, and the 1760-Series Option
SC adds the same component analog measurement capability to a 1750A-Series
instrument.
Servicing Information
This manual supports both module level (for module exchange) and component
level servicing. Module level servicing uses the block diagram and its descrip-
tions to isolate a problem to the circuits on a particular circuit board. Component
level servicing also uses the theory of operation, schematic diagrams and circuit
board parts locating illustration and cross reference indexes (part location charts).
Specific procedures for troubleshooting and disassembly in this manual should
only be attempted by competent service technicians. Be sure to read and follow
all Warnings and Cautions when performing maintenance.
The last sections of this manual contain the Replaceable Parts Lists, Circuit
Board Illustrations, and Schematic Diagrams needed to isolate and replace faulty
components. Replacement part ordering information can be found in the
Maintenance section of this manual.
Performance Verification
These instruments are designed to be returned to operation within stated
specifications through a PC-based adjustment procedure. The disk holder for this
manual contains two computer disks: 1. A software disk containing instruments
operating software (Version 2.2 or greater). 2. A calibration software disk.
An IBM compatible personal computer (PC) with a DOS 3.3 or higher operating
system, and a 31/2inch high density floppy drive is required to perform the
readjustment procedure or reload the operating software.
The spare software disk is provided in case the Main circuit board, which
contains the software, requires replacement. In all cases, the operating software
must be Version 2.2 or above to perform the Readjustment Procedure.
The specifications contained in the Specification section of this manual contain
Performance Verification step numbers.

Preface
xiv 1740A Series, 1750A Series, & 1760 Series Service Manual
Contacting Tektronix
Phone [phone]*
Address Tektronix, Inc.
Department or name (if known)
14200 SW Karl Braun Drive
P.O. Box 500
Beaverton, OR 97077
USA
Web site www.tektronix.com
Sales support 1-800-833-9200, select option 1*
Service support 1-800-833-9200, select option 2*
Technical support Email: [e-mail]
1-800-833-9200, select option 3*
6:00 a.m. -- 5:00 p.m. Pacific time
*This phone number is toll free in North America. After office hours, please leave a
voice mail message.
Outside North America, contact a Tektronix sales office or distributor; see the
Tektronix web site for a list of offices.

1740A Series, 1750A Series, & 1760 Series Service Manual 1-1
Specifications
The tables in this chapter list the specifications for the 1740A, 1750A, and 1760
Series waveform monitors. Items listed in the Performance Requirement column
are generally quantitative, and can be tested by the Performance Verification
procedure in the service manual. Items listed in the Reference Information
column are useful operating parameters that have typical values; information in
this column is not guaranteed.
The second column of the two column format contains all of the descriptive
material about the listed characteristic. The performance verification procedure
step number, used to verify the characteristic, is also in this column. This series
of instruments is designed to operate on both PAL and NTSC standards, so some
of the tolerances are defined in millivolts and IREs; in these dual value toler-
ances, PAL values appear in parentheses.
Performance Requirements (Req) . Items with this designation are critical to
instrument performance. In most cases, a tolerance and a performance verifica-
tion step number are listed. However, there are a few areas where instrument
operation verifies that the performance requirement is met.
Reference Information (RI). This information about the instrument operation may
have a tolerance listed, but these should be considered as typical, not absolute.
Performance Verification Step. This item identifies the location of the test method
in the Performance Verification procedure.
The specifications listed in the Electrical Specifications portion of these tables
apply over an ambient temperature range of +0 _Cto+40_C. The rated
accuracies are valid when the instrument is calibrated in an ambient temperature
range of +20 _Cto+30_C.
Product Description
The 1740A/1750A/1760 Series is a half-rack width by three-rack-unit high
instrument. It is a versatile waveform monitor/vectorscope for composite and
component television signals. Most circuitry and the mechanical components are
shared throughout the series. In addition to NTSC and PAL standard versions, a
dual standard (NTSC/PAL) version is available.

Specifications
1-2 1740A Series, 1750A Series, & 1760 Series Service Manual
These instruments employ a bright, post accelerated CRT with lighted internal
graticule. The parallax free internal graticule structure contains targets and
markings for both the vector and waveform functions. The “Lightning”graticule,
for the 1760 Series, is electronic, in order to keep from complicating the
waveform/vector graticule. Option 74, which uses a white phosphor (P4) CRT, is
available for all three instrument series.
These monitors are microprocessor controlled to provide greater versatility.
Switch settings, affecting the operation of the instrument, are continuously
polled by the processor, with any change in status acted upon immediately.
Current operating conditions are preserved in Non-Volatile Random Access
Memory (NOVRAM), which returns the front panel settings to the current
settings, in the event of power interruption (either accidental or routine power
down).
Many operational measurements are performed on a repetitive basis, and these
instruments provide a method of repeating common measurements by simply
selecting stored measurement settings from a CRT menu list. The common
measurement front panel settings can be stored and named by the user. Measure-
ment specific, front-panel settings can be recalled by pushing the front-panel
Preset Menu button and selecting the desired preset by name or number.
Many functions that were formerly selected by changing internal jumpers and/or
wire straps are now accessible through on screen menu selections. Menus are
selected by pushing the appropriate front panel Menu selection. Menu items are
then selected by pushing one or more of the assignable switches and/or rotating
the assigned front-panel control. Once selected these menu choices are retained
until changed by subsequent reconfiguration.
The front panel provides both assignable switches (located next to the CRT) and
controls (located beneath the CRT), that operate with CRT readout to increase
functionality without cluttering the limited front panel area. Function of these
switches and controls is dictated by the front-panel Display and initial Menu
choices.
The 1740A Series is a full capability waveform/vector monitor that also provides
audio and time code measurements. The 1750A Series has all of the capabilities
of the 1740A Series, with the addition of SCH phase measurements.
The 1760 Series combines component measurements with the composite
capabilities of the 1740A/1750A Series. It incorporates all of the measurements
of the 1740A Series with a full set of component analog measurements. The
assignable cursors, along with the CRT readout can be used for time, voltage,
and phase measurements. The system of Menus and CRT readout simplifies the
configuration of this monitor for measurement or monitoring of signal character-
istics.