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Service Manual
SD-22 & SD-26
Sampling Head
070-7227-02
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 the Safety Summary prior to per-
forming service.
Please check for change information at the rear
of this manual.
First Printing: May 1993
www.tektronix.com
Instrument Serial Numbers
Each instrument manufactured by Tektronix has a serial number on a panel insert or tag, or stamped on the
chassis. The first letter in the serial number designates the country of manufacture. The last five digits of the
serial number are assigned sequentially and are unique to each instrument. Those manufactured in the
United States have six unique digits. The country of manufacture is identified as follows:
B010000 Tektronix, Inc., Beaverton, Oregon, USA
E200000 Tektronix United Kingdom, Ltd., London
J300000 Sony/Tektronix, Japan
H700000 Tektronix Holland, NV, Heerenveen, The Netherlands
Instruments manufactured for Tektronix by external vendors outside the United States are assigned a two digit
alpha code to identify the country of manufacture (e.g., JP for Japan, HK for Hong Kong, IL for Israel, etc.).
Tektronix, Inc., P Box 500, Beaverton, OR 97077
.O.
Printed in U.S.A.
Copyright E Tektronix, Inc., 1989, 1993. All rights reserved. Tektronix products are covered by U.S. and
foreign patents, issued and pending. The following are registered trademarks: TEKTRONIX, TEK,
TEKPROBE, and SCOPE MOBILE.
WARRANTY
Tektronix warrants that this product will be free from defects in materials and workmanship for a period of one (1) year from the
date of shipment. If any such 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; or c) 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 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 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.
Table of Contents
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
General Information
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Safety Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Installing and Removing the Sampling Head . . . . . . . . . . . . . . . 14
Packaging for Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Operating Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Checks and Adjustments
Checks and Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Using These Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Conventions in this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Initialized and Stored Settings . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Menu Selections and Measurement Techniques . . . . . . . . . . . 25
Setup Illustrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Part 1 Power On . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Part 2 Dot Transient Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 10
Part 3 Offset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 16
Part 4 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 20
Part 5 Rise Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 23
Part 6 Acquisition Aberrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 26
Part 7 Coincidence Between Channels . . . . . . . . . . . . . . . . . . . . 2 30
Part 8 Maximum Signal Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 33
Part 9 Isolation Between Channels . . . . . . . . . . . . . . . . . . . . . . . . 2 36
Maintenance
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Periodic Electrical Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
SD 22 & SD 26 Service Manual i
Table of Contents
Static Sensitive Device Classification . . . . . . . . . . . . . . . . . . . . 31
Exchanging Sampling Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Removing and Replacing the Sampling Head Internal
Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Changing the Sampling Head Identification Number . . . . . . . 36
Theory of Operation
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
System Functional Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Loop Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Offset Null . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Replaceable Parts
Replaceable Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Parts Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Using the Replaceable Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . 52
ii Contents
List of Figures
Figure 1 1: Sampling Head Compartments in an 11801B and a
CSA 803A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 1 2: Installing a Sampling Head in an Instrument . . . . . . . . . . 15
Figure 2 1: Locations of Controls and Connectors on Mainframe
Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 7
Figure 3 1: Sampling Head Screw Locations . . . . . . . . . . . . . . . . . . . . 3 5
Figure 3 2: A5 Time Base/Controller Board Jumper Location . . . . . . 3 7
Figure 4 1: SD 22 and SD 26 Sampling Head Block Diagram . . . . . . 4 1
Figure 4 2: Displayed Traces at Various Loop Gain Settings . . . . . . . 4 2
Figure 5 1: Exploded View of the SD 22 and SD 26 Sampling
Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
SD 22 & SD 26 Service Manual iii
List of Figures
iv Contents
List of Tables
Table 2 1: Measurement Limits and Specifications . . . . . . . . . . . . . . . 21
Table 2 2: Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 2 3: Aberration Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 26
Table 3 1: Relative Susceptibility to Electrostatic Discharge (ESD) . . 32
SD 22 & SD 26 Service Manual v
List of Tables
vi Contents
General Information
General Information
This section gives all the information needed to apply power to the SD 22 &
SD 26 Sampling Heads.
Safety information as well as information on installing and removing the
sampling head, packaging for shipment, and environmental conditions such
as operating temperature is included here.
Introduction The SD 22 & SD 26 Sampling Head Service Manual is designed for use by
qualified service personnel. It contains information necessary to check and
maintain the SD 22 & SD 26 Sampling Heads.
The SD 22 Sampling Head is a two channel, low noise, 28 ps rise time
sampling head. The SD 26 Sampling Head is a two channel, 17.5 ps rise
time sampling head. The SD 22 & SD 26 Sampling Heads are designed for
use in the 11800 Series Digital Sampling Oscilloscopes, the SM 11 Multi
Channel Unit, and the CSA 803 Series Communications Signal Analyzers.
SD 22 & SD 26 Service Manual 11
General Information
The general safety information in this part of the summary is for both operat
Safety Summary
ing and servicing personnel. Specific warnings and cautions will be found
throughout the manual where they apply, but may not appear in this
summary.
Terms in Manuals
CAUTION statements in manuals identify conditions or practices that could
result in damage to the equipment or other property.
WARNING statements in manuals identify conditions or practices that could
result in personal injury or loss of life.
Terms on Equipment
CAUTION on equipment means a personal injury hazard not immediately
accessible as one reads the marking, or a hazard to property including the
equipment itself.
DANGER on equipment means a personal injury hazard immediately acces
sible as one reads the marking.
Symbols in Manuals
Static Sensitive Devices
Symbols on Equipment
DANGER Protective ATTENTION
High Voltage ground (earth) Refer to
terminal manual
Grounding the Instrument
The sampling head is grounded through the grounding conductor of the
oscilloscope's power cord. To avoid electric shock, plug the power cord into
a properly wired receptacle before connecting to the product input or output
terminal. A protective ground connection, by way of the grounding conduc
tor in the power cord, is essential for safe operation.
Danger Arising from Loss of Ground
Upon loss of the protective ground connection, all accessible conductive
parts (including knobs and controls that may appear to be insulating), can
render an electric shock.
12 General Information
General Information
Do Not Operate in Explosive Atmospheres
To avoid explosion, do not operate the sampling head in an atmosphere of
explosive gasses.
SD 22 & SD 26 Service Manual 13
General Information
Installing and To avoid damage to the instrument, set the instrument's ON/STANDBY
switch to STANDBY before installing or removing the sampling head.
Removing the
Sampling Head The SD 22 & SD 26 Sampling Head slide into the one of the front panel
compartments of the 11800 Series Digital Sampling Oscilloscopes or CSA
803 Series Communications Signal Analyzers. Figure 1 1 shows the front
panel of an instrument and the locations of the sampling head
compartments.
Sampling Head
Compartments
11801B
Sampling Head
Compartments
CSA 803A
Power Only Sampling
Head Compartments
Figure 1 1: Sampling Head Compartments in an 11801B and a
CSA 803A
14 General Information
General Information
With the ON/STANDBY switch set to STANDBY, place the sampling head in a
compartment and slowly push it in with firm pressure. Once the sampling
head is seated, turn the lock down screw to tighten the sampling head into
place. See Figure 1 2.
CAUTION
To prevent damage to your instrument or sampling head, never
install or remove a sampling head when the ON/STANDBY switch
is ON.
If the green indicator light remains on when the STANDBY position
is selected, then the switch has been left internally disabled after
the servicing of the power supply. To enable the ON/STANDBY
switch, refer to the Maintenance section of the Service Manual for
your mainframe instrument.
To remove the sampling head from an instrument, set the instrument's
ON/STANDBY switch to STANDBY. Turn the lock down screw and then
slowly pull out the sampling head.
Mainframe
Lock Down
Screw
Sampling
Head
Figure 1 2: Installing a Sampling Head in an Instrument
SD 22 & SD 26 Service Manual 15
General Information
Packaging for If possible, save and reuse the original carton and packaging to the pack
age sampling head when shipping it by commercial transportation.
Shipment
Attach a tag to the sampling head if it is shipped to your local Tektronix
service center for service or repair. Include the following information on the
tag:
H Name and address of the instrument and sampling head owner.
H Name of a person at your firm who can be contacted about the instru
ment and sampling head.
H Complete instrument and sampling head type and serial number.
H A description of the service required.
Package the sampling head as follows, if the original package is not avail
able or is not fit for use:
Step 1: Attach short circuit terminations to the sampling head inputs.
Step 2: Obtain a corrugated cardboard carton with inside dimensions at
least six inches (15 cm) greater than the sampling head dimensions.
Use a carton with a bursting test strength of at least 200 pounds per
square inch.
Step 3: Fully wrap the sampling head with antistatic sheeting, or its
equivalent, to protect the finish.
Step 4: Tightly pack dunnage or urethane foam between the carton and
the sampling head to cushion the sampling head on all sides. Allow
three inches of packing on each side.
Step 5: Seal the carton with shipping tape or with industrial staples.
Step 6: Mark the address of the Tektronix service center and your return
address on the carton in one or more prominent places.
16 General Information
General Information
Operating The following environmental requirements are provided to ensure proper
operation and long sampling head life.
Environment
Operating Temperature
Operate the sampling head where the ambient air temperature is between
0_ C and +50_ C. Store the sampling head in ambient temperatures from
-40_ C to +75_ C. After storage at temperatures outside the operating
limits, allow the chassis to reach the operating temperature range before
applying power.
Allow a 20 minute warmup before performing the calibrations in the
Enhanced Accuracy menu of the instrument mainframe. Calibrations should
be repeated if the temperature changes more than "5