Tektronix 2246 1Y User manual

TEKSERVICE
MANUAL
■HW hMhS| M |
^ ^ ■ 2 4 6 MO|§A
B M w B ^ TABLEiW W i
OSCILLOSCOPE
SN B700100 nd ABOVE (2246 1Y, 2R)
SN B100100 nd ABOVE (2246 MOD A)
Tektronix
C OM M O TE D TO E XCELLENCE

TEK SERVICE MANUAL
n
P rt No. 070-7062-00
Product Group 46
2246 1Y, 2R
nd
2246 MOD A
PORTABLE
OSCILLOSCOPE
SERVICE
' ^ SNB700100 nd ABOVE (2246 1Y,2R)
-<■ SN B100100 nd ABOVE (2246 MOD A)
The 2246 2R Is a rackmount version of the 2246 1Y. This service
r~ manual and the 2240 1R Instruction sheet (Tektronix part number
070-6332-00) are required to fully service the 2246 2R
oscilloscope.
' i
WARNING |
The following servicing instructions
re for use by qu lified service
personnel only. To void person l
injury, do not perform ny servicing
unless you re qu lified to do so.
Refer to the S fety Summ ry prior
to performing ny service.
[
I
r
Please check for CHANGE IN ORMATION
at the rear of this manual.
First Printing JUL 1988
Revised OCT 1991 Ifektronix
C O M M IT T E D T O E X C E LL E N C E

Copyright© 1988 Tektronix, In . All rights reserved. Contents of this
publi ation may not be reprodu ed in any form without the written
permission of Tektronix, In .
Produ ts of Tektronix, In ., and its subsidiaries are overed by U.S.
and foreign patents issued and pending.
TEKTRONIX, TEK, SCOPE-MOBILE, and
trademarks of Tektronix, In . are registered
Printed in U.S.A. Spe ifi ation and pri e hange privileges are
reserved.
INSTRUMENT SERIAL NUMBERS
Ea h instrument has a serial number on a panel insert, tag, or
stamped on the hassis. The first two digits designate the ountry of
manufa ture. The last five digits of the serial number are unique to
ea h instrument. The ountry of manufa ture is identified as follows:
B000000 Tektronix, In ., Beaverton, Oregon, U.S.A.
E200000 Tektronix United Kingdom, Ltd., Marlow
G100000 Tektronix Guernsey, Ltd., Channel Islands
HK00000 Hong Kong
H700000 Tektronix Holland, NV, Heerenveen,
The Netherlands
JP00000 Sony/Tektronix, Japan

2246 1Y nd 2246 Mod A Service
TABLE OF CONTENTS
P ge P ge
LIST OF ILLUSTRATIONS....................................... vi
LIST OF TABLES . ....................................................... vii
OPERATORS SAFETY SUMMARY...................... viii
SERVICING SAFETY SUMMARY . ......................... ix
Section 1 SPECIFICATION
INTRODUCTION .............................. 1-1
STANDARD ACCESSORIES ___ 1-1
RECOMMENDED RECALIBRATION
SCHEDULE
................... 1-1
PERFORMANCE CONDITIONS . . 1-2
Section 2 PREPARATION FOR USE
SAFETY...........................................2-1
LINE VOLTAGE AND POWER
CORD .............................................2-1
LINE FUSE .................................... 2-1
INSTRUMENT COOLING . .......... 2-2
START-UP ...................................... 2-2
DETAILED OPERATING
INFORMATION
................................ 2-2
Section 3 THEORY OF OPERATION
SECTION ORGANIZATION .......... 3-1
INTEGRATED CIRCUIT
DESCRIPTIONS ..............................3-1
BLOCK DIAGRAM
DESCRIPTION .................................... 3-1
INTRODUCTION..............................3-1
VERTICAL INPUTS
(Diagram 1) .............................. 3-1
VERTICAL PREAMPS AND
OUTPUT AMPLIFIER
(Diagram 2) .............................. 3-2
A AND B TRIGGER SYSTEM
(Diagram 3) .............................. 3-2
DISPLAY AND TRIGGER LOGIC
AND PROCESSOR INTERFACE
(Diagram 4) .............................. 3-3
A AND B SWEEPS AND
DELAY COMPARATORS
(Diagram 5) .............................. 3-4
HORIZONTAL OUTPUT
AMPLIFIER (Diagram 6 ) ........... 3-4
Z-AXIS, CRT, PROBE ADJUST,
AND CONTROL MUX
(Diagram 7) .............................. 3-4
MEASUREMENT PROCESSOR
(Diagram 8) .............................. 3-5
READOUT SYSTEM
(Diagram 9) .............................. 3-5
SWITCH BOARD AND INTERFACE
(Diagram 10) ............................ 3-6
ADC AND DAC SYSTEM
(Diagram 11) ............................ 3-6
POWER SUPPLY
(Diagram 12) ............................ 3-6
DETAILED CIRCUIT DESCRIPTION 3-6
VERTICAL INPUTS
(Diagram 1) .............................. 3-6
VERTICAL PREAMPS AND OUTPUT
AMPLIFIER (Diagram 2 ) ........... 3-9
A AND B TRIGGER SYSTEM
(Diagram 3) ............................ 3-12
DISPLAY AND TRIGGER LOGIC
AND PROCESSOR INTERFACE
(Diagram 4)
............................ 3-16
REV OCT 1991 i

2246 IV nd 2246 Mod A Service
Section 4
TABLE OF CONTENTS (cont)
P ge P ge
A AND B SWEEPS AND DELAY
COMPARATORS
(Diagram 5) ................................3-31
HORIZONTAL OUTPUT AMPLIFIER
(Diagram 6) ................................3-37
Z-AXIS, CRT, PROBE ADJUST,
AND CONTROL MUX
(Diagram 7) ................................ 3-38
MEASUREMENT PROCESSOR
(Diagram 8) ................................ 3-42
READOUT SYSTEM
(Diagram 9) ................................ 3-45
SWITCH BOARD AND
INTERFACE (Diagram 10) ------- 3-51
ADC AND DAC SYSTEM
(Diagram 11) ..............................3-52
POWER SUPPLY
(Diagram 12) ..............................3-53
MAIN BOARD POWER
DISTRIBUTION
(Diagram 13) ..............................3-58
PROCESSOR POWER BOARD
DISTRIBUTION (Diagram 14) . . 3-58
INTERCONNECTION DIAGRAM
(Diagram 15) ..............................3-58
PERFORMANCE CHECK PROCEDURE
INTRODUCTION .................................. 4-1
TEST EQUIPMENT REQUIRED . . 4-1
PERFORMANCE CHECK
INTERVAL ...................................... 4-1
PREPARATION ................................ 4-1
INDEX TO PERFORMANCE
CHECK PROCEDURE . ...................4-4
DISPLAY .............................................4-5
TRACE ROTATION . .......................4-5
GEOMETRY .................................... 4-5
VERTICAL ....................................... 4-6
Input COUPLING Fun tional
Che k ......................................... 4-6
CH 1 and CH 2 VOLTS/DIV
Tra e Shift ................................ 4-6
CH 3 and CH 4 VOLTS/DIV
Tra e Shift ................................ 4-7
CH 1 and CH 2 VAR VOLTS/DIV
Tra e Shift ................................ 4-7
CH 1 and CH 2 Input
COUPLING Tra e S h ift ............. 4-7
CH 2 INVERT Tra e Shift......... 4-7
CH 1 and CH 2 VAR
VOLTS/DIV Range ................... 4-7
Low-Frequen y Linearity......... 4-8
CH 1 and CH 2 Verti al
Defle tion A ura y
................. 4-8
Ch 3 and CH 4 Verti al
Defle tion A ura y ................. 4-8
ADD Mode and CH 2 INVERT
Defle tion A ura y ................. 4-9
Verti al POSITION Range
(all hannels) .............................. 4-9
CH 1 to CH 2 Signal
Delay Mat h .............................. 4-10
CH 1 to CH 4 Signal
Delay Mat h ............................ 4-10
CH 3 to CH 4 Signal
Delay Mat h .............................. 4-10
CH 1 and CH 2 Verti al
Bandwidth .................................. 4-10
CH 3 and CH 4 Verti al
Bandwidth ................................ 4-11
CH 1 and CH 2 Aberrations . 4-11
SCOPE BW (Bandwidth
Limit) A ura y ..................... 4-11
Common-mode Reje tion
Ratio .......................................... 4-12
Channel Isolation ..................... 4-12
ii REV OCT 1991

2246 1Y nd 2246 Mod A Service
TABLE OF CONTENTS (cont)
P ge P ge
AC-Coupled Lower -3 dB
Point .............................................4-13
Verti al ALT and CHOP
Modes .......................................... 4-13
BEAM FIND Fun tional
C he k..........................................4-13
A and B Tra e
Separation .................................. 4-13
TRIGGERING ................................. 4-14
500 Hz Trigger
Sensitivity ................................... 4-14
500 kHz Trigger
Sensitivity ................................... 4-15
25 MHz Trigger
Sensitivity .................................. 4-15
100 MHz Trigger
Sensitivity .................................. 4-15
100 MHz NOISE REJ
Trigger Sensitivity ................... 4-16
Single Sweep Mode ................. 4-16
Trigger LEVEL Control
Range .........................................4-16
TV Field Trigger
Sensitivity .................................. 4-17
TV Line Trigger
Sensitivity .................................. 4-17
Line Trigger Fun tional
C he k ......................................... 4-17
HORIZONTAL ................................ 4-18
A and B Sweep Length ........... 4-18
Horizontal POSITION
Range . ........................................ 4-18
VAR SEC/DIV Range ............... 4-18
Magnifier Registration ............. 4-19
A and B Timing A ura y
and Linearity .............................. 4-19
A and B Magnified Timing
A ura y .................................. 4-19
Delay Time Jitter . ..................... 4-20
Delay Time A ura y ............. 4-21
Delay Time Position
Range ....................................... 4-21
X-Axis Gain A ura y .......... 4-21
X-Y Phase Differen e ........... 4-22
X-Axis Bandwidth ................... 4-22
TIME AND CURSORS
MEASUREMENTS ........................ 4-23
k- SEC -H and k- 1/SEC-M
Cursor A ura y ................... 4-23
Delta Time A ura y ............. 4-23
k- phase -H Cursor
A ura y................................... 4-24
k- VOLTS -H Cursor
A ura y .................................. 4-24
rh v o lts -H Cursor
A ura y .................................. 4-24
Tra king Cursors Position
A ura y .................................. 4-24
CH1/CH2 VOLTMETER
MEASUREMENTS ........................ 4-25
DC Volts A ura y ................. 4-25
DC Volts Normal Mode
Reje tion Ratio........................ 4-25
+Peak, -Peak, Peak-to-Peak
Volts A ura y........................ 4-26
25 MHz +Peak, -Peak, and
Peak-to-Peak Volts
A ura y . .................................. 4-26
100 MHz +Peak, -Peak, and
Peak-to-Peak Volts
A ura y .................................. 4-26
Gated Volts A ura y . .......... 4-26
EXTERNAL Z-AXIS, PROBE
ADJUST AND FRONT-PANEL
SETUP FUNCTIONS ..................... 4-28
Che k External Z-Axis
Input ......................................... 4-28
PROBE ADJUST Output ......... 4-28
Run MAKE FACTORY SETTINGS
Routine ..................................... 4-28
iii
REV OCT 1991

2246 1Y nd 2246 Mod A Service
Section 5
TABLE OF CONTENTS (cont)
P ge P ge
ADJUSTMENT PROCEDURE
INTRODUCTION . ................................5-1
PURPOSE .................................... 5-1
TEST EQUIPMENT
REQUIRED ...................................... 5-1
LIMITS AND TOLERANCES .......... 5-1
PARTIAL PROCEDURES ............... 5-1
INTERNAL ADJUSTMENTS AND
ADJUSTMENT INTERACTION ... 5-1
PREPARATION FOR
ADJUSTMENT ................................ 5-3
INDEX TO ADJUSTMENT
PROCEDURE .................................. 5-3
POWER SUPPLY, DISPLAY,
AND Z-AXIS ...................................... 5-4
INITIAL CONTROL
SETTINGS ...................................... 5-4
PROCEDURE .................................. 5-4
Power Supply DC Levels
(R2252)......................................... 5-4
Grid Bias (R2719) ....................... 5-5
Astigmatism (R2788) ................. 5-5
Tra e Rotation (Front Panel) . . 5-5
Geometry (R2784)
..................... 5-5
Z-Axis Response (C2704) on
instruments with serial numbers
of below B110100 for the 2246
MOD A or below B710100
for the 2246 1Y ............................5-5
Readout Jitter (R724) ............... 5-6
VERTICAL...........................................5-7
INITIAL CONTROL
SETTINGS ........................... 5-7
PROCEDURE .................................. 5-7
Verti al Output Gain (R703) and
Readout Verti al Centering
(R260) .
. ........................................ 5-7
CH 1 Step Balan e (R12) ......... 5-7
CH 2 Step Balan e (R22) ___ .5-8
CH 3 Step Balan e (R141) ... 5-8
CH 4 Step Balan e (R161) ... 5-8
CH 1 MF/LF Gain (R13) and
Compensation (Cl)
................. 5-8
CH 1 Input Capa itan e (Cl 14) 5-8
CH 1 Input Compensation X I0
(C11)........................................... 5-8
CH 1 Input Compensation
X I00 (C IO )
........... .. ................. 5-8
CH 1 Gain (R211) ................... 5-8
CH 2 MF/LF Gain (R23) and
Compensation (C2)
................. 5-8
CH 2 Input Capa itan e (Cl 24) 5-9
CH 2 Input Compensation
X I0 (C21) .................................. 5-9
CH 2 Input Compensation
X I00 (C20) .................................. 5-9
CH 2 Gain (R221) ................... 5-9
CH 3 MF/LF Compensation
(Cl 34 )......................................... 5-9
CH 3 Gain (R231) ................... 5-9
CH 4 MF/LF Compensation
(Cl 5 4 )......................................... 5-9
CH 4 Gain (R241) ................... 5-9
Delay-line HF Compensation
(R272, R273, R275, C274,
C273) ................................ 5-10
CH 3 HF Compensation
(Cl 3 8 )....................................... 5-10
CH 4 HF Compensation
(Cl 58 ) ........................................ 5-10
CH 1 and CH 2 Bandwidth
Che k
. ........................................ 5-10
CH 3 and CH 4 Bandwidth
Che k ........................................ 5-11
HORIZONTAL .................................. 5-12
INITIAL CONTROL
SETTINGS .................................. 5-12
PROCEDURE .............................. 5-12
Horizontal XI Gain (Timing)
(R826) ........................................ 5-12
iv REV OCT 1991

2246 1Y nd 2246 Mod A Service
Horizontal X I0 Gain (Timing)
(R825) ......................................... 5-12
Readout Horizontal Gain (R823)
and MAG Registration (R809) . 5-12
A 0.5 p.s Timing (C314) .......... 5-13
B 0.5 |xs Timing (C329) ......... 5-13
2-5 ns Timing (C807, C814) . 5-13
X Gain (R827) .......................... 5-13
MEASUREMENT BANDWIDTH AND
SELF CHARACTERIZATION .......... 5-14
INITIAL CONTROL
SETTINGS .................................... 5-14
PROCEDURE ................................ 5-14
Volts Cal (R920) ..................... 5-14
B Trigger Bandwidth (R455) . . 5-14
Self Chara terization
................. 5-14
Section 6 MAINTENANCE
STATIC-SENSITIVE
COMPONENTS .................................. 6-1
PREVENTIVE MAINTENANCE .......... 6-2
INTRODUCTION..............................6-2
INSPECTION AND
CLEANING ...................................... 6-2
LUBRICATION ................................ 6-4
SEMICONDUCTOR CHECKS ___ 6-4
PERIODIC READJUSTMENT ____ 6-4
TROUBLESHOOTING ..................... . 6-5
INTRODUCTION..............................6-5
TROUBLESHOOTING AIDS .......... 6-5
TROUBLESHOOTING
EQUIPMENT .................................... 6-6
TROUBLESHOOTING
TECHNIQUES ................................ 6-6
INTERNAL TESTING
CAPABILITIES ..............................6-10
SERVICE MODE ......................... 6-11
TROUBLESHOOTING HINTS
BY DIAGRAM ..............................6-19
TROUBLESHOOTING MEASURE
MENT ERRORS............................6-25
CORRECTIVE MAINTENANCE . . . 6-34
INTRODUCTION........................ 6-34
MAINTENANCE
PRECAUTIONS.......................... 6-34
OBTAINING REPLACEMENT
PARTS....................................... 6-34
REPACKAGING FOR
SHIPMENT ................................ 6-35
MAINTENANCE AIDS ............. 6-35
INTERCONNECTIONS ............. 6-35
BATTERY .................................. 6-37
TRANSISTORS AND
INTEGRATED CIRCUITS ......... 6-37
SOLDERING TECHNIQUES . . . 6-37
REMOVAL AND REPLACE
MENT INSTRUCTIONS ............. 6-38
Section 7 OPTIONS
INTRODUCTION .......................... 7-1
INTERNATIONAL POWER
CORDS ....................................... 7-1
OPTION 1R RACKMOUNTED
INSTRUMENT .............................. 7-1
Section 8 REPLACEABLE ELECTRICAL PARTS
Section 9 DIAGRAMS
Section 10 REPLACEABLE MECHANICAL PARTS
CHANGE INFORMATION
REV OCT 1991 V

2246 1Y nd 2246 Mod A Service
LIST OF ILLUSTRATIONS
Figure P ge
The 2246 1Y and Mod A
Portable Os illos ope .................................. x
1-1 Maximum input voltage vs frequen y
derating urve for the CH 1, CH 2,
CH 3, or CH 4 input onne tors .... 1-14
1-2 Dimensional outline drawing,
standard abinet .................................... 1-20
1- 3 Dimensional outline drawing,
ra kmount abinet .................................. 1-21
2- 1 Optional power ords ...............................2-1
3 - 1 Display Sequen er 1C (SLIC, U600)
pin-out diagram .................................... 3-16
3-2 Readout interfa e relative
signal tim ing.............................................3-25
3-3 Trigger Logi 1C (FLIC, U602)
pin-out diagram ...................................... 3-26
3-4 Simplified Sweep Cir uit ........................ 3-32
3-5 A Sweep Start ir uit waveforms .... 3-36
3-6 Simplified diagram of the DC
Restorer ir uitry .................................... 3-40
3-7 Display addresses ................................... 3-48
3-8 Chara ter pixel arrangement ................3-50
3-9 Power Supply blo k diagram ................ 3-54
3-10 Preregulator swit hing waveforms . . . 3-56
5-1 Areas of waveform affe ted by
HF ompensation .................................... 5-10
5- 2 2-5 ns Timing............................................5-13
6- 1 Power-on test failure odes .................. 6-10
6-2 Initial SERVICE MENU...............................6-11
6-3 SERVICE MENU with DIAGNOSE
hoi e sele ted .................................. 6-12
6-4 Main board removal ............................ 6-44
6-5 Delay-line onne tions to top of
Main board ........................................... 6-45
9-1 Color odes for resistors
9-2 Semi ondu tor lead onfigurations
9-3 Lo ating omponents on s hemati
diagrams and ir uit board illustrations
9-4 Simplified 2246 1Y and 2246 Mod A
blo k diagram
9-5a Detailed 2246 1Y or 2246 Mod A blo k
diagram—part 1
9-5b Detailed 2246 1Y or 2246 Mod A blo k
diagram—part 2
9-6a A10-Main board for SN B715000 and
above (2246 1Y), and B120000 and above
(2246 Mod A)
9-6b A10-Main board for SN B710100 to
B714999 (2246 1Y), and SN B110100 to
B119999 (2246 Mod A)
9-6 A10-Main board for SN B710099 and
below (2246 1Y), and B110099 and below
(2246 Mod A)
9-7 A9-2 mV Bandwidth board for SN B700100
to B714999 (2246 1Y), and SN B100100
to B119999 (2246 Mod A)
9-8 Hybrid pin identifiers
9-9 A8—CRT Control board
9-10 A16—Pro essor board
9-11 A14—Swit h board
9-12 A12—Potentiometer board
9-13 A18—Power Supply board
9-14 A10—Main board adjustment lo ations
vi REV OCT 1991

2246 1Y nd 2246 Mod A Service
LIST OF TABLES
T ble P ge
1-1 Ele tri al Chara teristi s ......................... 1-3
1-2 Environmental Chara teristi s .............. 1-15
1-3 Me hani al Chara teristi s ................... 1-17
3-1 Shift Register 0 Bit Assignment ............ 3-7
3-2 Input Coupling Control Bit S tates ........ 3-8
3-3 CH 1 and CH 2 Attenuator and Gain
Control Bit States ...................................... 3-9
3-4 CH 2 INVERT Control Bit .........................3-9
3-5 CH 3 and CH 4 Gain Control B it ........ 3-10
3-6 Trigger Sele tion Logi .........................3-13
3-7 Display Sequen er (U600) Control
Bit Assignments ...................................... 3-18
3-8 A Trigger Sour e Sele t Bits .............. 3-19
3-9 Horizontal Display Mode Sele t Bits . . 3-19
3-10 Shift Register 1 Control Bit Data .... 3-20
3-11 Trigger Sour e S ele t...........................3-21
3-12 Verti al MODE Sele t ...........................3-21
3-13 Horizontal MODE Sele t ...................... 3-21
3-14 Holdoff Counter En oding .................... 3-22
3-15 Display Sequen er Channel Sele t
Logi Bits .................................................3-23
3-16 Horizontal and Verti al Display
Response ............................................... 3-24
3-17 Trigger Logi 1C Addressing Logi . . . 3-27
3-18 Control Register Signal-bit Names . . . 3-28
3-19 Delay Mode Sele tion Control Bits . . . 3-28
3-20 Peak Volts Dete tion Mode Logi . . . 3-28
3-21 Z-Axis Swit hing Logi ......................... 3-30
3-22 A Sweep Timing Sele tions ................. 3-34
3-23 B Sweep Timing Sele tions ................... 3-35
3-24 HD0 and HD1 Logi ................................3-37
P ge
3-25 Front-Panel Multiplexer Channel
Sele t Bits ............................................. 3-41
3-26 Measurement Pro essor Signals .... 3-44
3-27 Position Enable Bit Assignment .......... 3-49
3-28 Field and Mixer Attribute Bit
Assignment . ........................................... 3-50
3-29 Display Possibilities .............................. 3-51
3- 30 Possible Signal Conditions
to U2416 ............................................... 3-51
4 - 1 Test Equipment Required ..................... 4-2
4-2 Signal-to-Grati ule A ura y .............. 4-8
4-3 Settings for Timing A ura y
Che ks ................................................. 4-20
4- 4 Delay Time A ura y ....................... 4-21
5 - 1 Adjustment Intera tions ......................... 5-2
5- 2 Power Supply Voltage Lim its................. 5-5
6- 1 Relative Sus eptibility to
Stati -Dis harge Dam age ................... 6-1
6-2 External Inspe tion Che klist................. 6-3
6-3 Internal Inspe tion Che klist ................ 6-3
6-4 Power Supply Voltage and
Ripple Lim its ........................................... 6-8
6-5 SERVICE MENU Sele tions ................ 6-12
6-6 DIAGNOSE ROUTINES ........................... 6-16
6-7 Horizontal Display State Logi ............ 6-22
6-8 Measurement Pro essor I/O
Memory M ap......................................... 6-23
6-9 Measurement Error Troubleshooting
Hints ...................................................... 6-26
6-10 Maintenan e Aids . ................................ 6-36
9-1 Signal Line Lo ations
REV OCT 1991 vii

2246 1Y and 2246 Mod A Servi e
OPERATORS SAFETY SUMMARY
The safety information in this summary is for operating personnel. Warnings and cautions will also be found
throughout the manual where they apply.
Terms in this M nu l
CAUTION statements identify onditions or pra ti es
that ould result in damage to the equipment or
other property.
WARNING statements identify onditions or pra ti es
that ould result in personal injury or loss of life.
Grounding the Product
This produ t is grounded through the grounding on
du tor of the power ord. To avoid ele tri al sho k,
plug the power ord into a properly wired re ep
ta le before making any onne tions to the produ t
input or output terminals. A prote tive ground on
ne tion, by way of the grounding ondu tor in the
power ord, is essential for safe operation.
Terms s M rked on Equipment
CAUTION indi ates a personal injury hazard not im
mediately a essible as one reads the markings, or
a hazard to property, in luding the equipment itself.
DANGER indi ates a personal injury hazard im
mediately a essible as one reads the marking.
Symbols in this M nu l
This symbol indi ates where appli able
autionary or other information is to
be found. For maximum input voltage
see Table 1-1.
D nger Arising From Loss of Ground
Upon loss of the prote tive-ground onne tion, all
a essible ondu tive parts, in luding knobs and
ontrols that may appear to be insulating, an ren
der an ele tri sho k.
Use the Proper Power Cord
Use only the power ord and onne tor spe ified for
your produ t.
Use only a power ord that is in good ondition.
For detailed information on power ords and on
ne tors, see Figure 2-2.
Symbols s M rked on Equipment Use the Proper Fuse
f
A
DANGER—High voltage.
Prote tive ground (earth) terminal.
ATTENTION—Refer to manual.
Power Source
To avoid fire hazard, use only a fuse of the orre t
type, voltage rating and current rating as spe ified in
the parts list for your produ t.
Do Not Oper te in n Explosive
Atmosphere
To avoid explosion, do not operate this instrument in
an explosive atmosphere unless it has been spe
ifi ally ertified for su h operation.
This produ t is intended to operate from a power
sour e that does not apply more than 250 V rms
between the supply ondu tors or between either
supply ondu tor and ground. A prote tive ground
onne tion, by way of the grounding ondu tor in
the power ord, is essential for safe operation.
Do Not Remove Covers or P nels
To avoid personal injury, do not remove the produ t
overs or panels. Do not operate the produ t with
out the overs and panels properly installed.
viii

2246 1Y nd 2246 Mod A Service
SERVICING SAFETY SUMMARY
FOR Q ALIFIED SERVICE PERSONNEL ONLY
Refer also to the preceding Operators Safety Summary
Do Not Service Alone
Do not perform internal servi e or adjustment of this
produ t unless another person apable of rendering
first aid and resus itation is present.
Use C re When Servicing With Power On
Dangerous voltages exist at several points in this
produ t. To avoid personal injury, do not tou h
exposed onne tions or omponents while power is
on.
Dis onne t power before removing prote tive
panels, soldering, or repla ing omponents.
Power Source
This produ t is intended to operate from a power
sour e that does not apply more than 250 volts rms
between the supply ondu tors or between either
supply ondu tor and ground. A prote tive ground
onne tion by way of the grounding onne tor in the
power ord is essential for safe operation.

2246A Servi e
7062-01
X
The 2246 1Y or 2246 Mod A Portable Os illos ope

Section 1 -2 2 4 6 1Y nd 2246 Mod A Service
SPECIFICATION
INTRODUCTION
The 2246 1Y and 2246 Mod A are 100 MHz, four-
hannel, dual-sweep, portable os illos opes for
general-purpose use. A mi ropro essor-based
operating system ontrols most of the fun tions in
ea h instrument, in luding a fully integrated menu-
driven voltage and time measurement system with
SmartCursors®. A menu-driven servi e mode
provides for onfiguring of ertain menu and readout
displays, internal alibration, and servi ing
diagnosti s. The instruments in lude additional EMI
shielding. (See Table 1-2, Environmental Chara ter
isti s, for more information.)
The verti al defle tion system has four input han
nels. Two hannels have 11 basi defle tion fa tors
from 2 mV to 5 V per division, and two hannels have
two basi defle tion fa tors of 0.1 V and 0.5 V per
division. Basi defle tion fa tors an be extended
with attenuator probes. VOLTS/DIV readouts are
swit hed to display the orre t verti al s ale fa tors
when properly oded probes are onne ted to the
verti al input onne tors.
The horizontal defle tion system provides single,
dual, or delayed sweeps from 0.5 s to 20 ns per divi
sion (delayed sweep, 5 ms to 20 ns per division). The
trigger system provides stable triggering over the full
bandwidth of the verti al defle tion system.
Alphanumeri rt readouts of the verti al and hori
zontal s ale fa tors are displayed at the bottom of the
s reen. On-s reen verti al and horizontal ursors
provide a urate voltage, time, frequen y, and
phase measurements; measurement values are dis
played at the top of the rt.
The measurement features in lude voltage measure
ments for+Peak, -Peak, Peak-to-Peak, and average
DC, or positionable ursors for measuring voltage dif
feren e, time differen e, frequen y, and phase.
SmartCursors® that visually tra k voltage measure
ments, trigger levels, and ground an be pla ed on
displayed waveforms. Delay-time and delta-delay
measurements for time, frequen y, and phase are
available in ALT and B Horizontal Modes.
STANDARD ACCESSORIES
The following items are standard a essories shipped
with the 2246 1Y and 2246 Mod A instrument:
2 Probes, 10X, 2 meter, with a essories
1 Probe, IX, 2 meter, with a essories
1 Power ord
1 Power ord lamp
1 CRT implosion shield, blue plasti (installed)
1 Fuse, 2A, 250 V, slow-blow
1 Atta hing a essory pou h
1 A essory pou h, ziplo
1 Front over
The following items are standard a essories shipped
with the 2246 1Y instrument:
2 Operators manuals
2 Servi e manuals
2 Referen e guides
The following items are standard a essories shipped
with the 2246 Mod A instrument:
1 Operators manual
1 Referen e guide
RECOMMENDED RECALIBRATION
SCHEDULE
To ensure a urate measurements, he k the per
forman e of this instrument every 2000 hours of
operation, or, if used infrequently, on e ea h year.
Repla ement of omponents in the instrument may
also ne essitate readjustment of the affe ted
ir uits.
NOTE
The silver-oxide batteries used in the
2246 1Y (instruments serial numbered
B714999 and below) M ST BE REPLACED
AT LEAST EVERY 12 MONTHS to ensure
proper operation of the instrument.
REV OCT 1991 1-1

Specific tion—2246 1Y nd 2246 Mod A Service
PERFORMANCE CONDITIONS
The ele tri al hara teristi s given in Table 1-1 are
valid when the instrument has been adjusted at an
ambient temperature between +20°C and +30°C,
has had a warm-up period of at least 20 minutes,
and is operating at an ambient temperature between
-10°C and +55°C (unless otherwise noted).
Items listed in the Performan e Requirements
olumn are verifiable qualitative or quantitative limits
that define the measurement apabilities of the
instrument.
Environmental hara teristi s are given in
Table 1-2. This instrument meets the requirements
of MIL-T-28800D, for Type III, Class 3, Style D
equipment, as des ribed in this se tion.
Physi al hara teristi s of the instrument are listed
in Table 1-3.
1-2

Specific tion—2246 1Y nd 2246 Mod A Service
Table 1-1
Ele tri al Chara teristi s
Chara teristi s Performan e Requirements
VERTICAL DEFLECTION SYSTEM - CH 1 AND CH 2
Defle tion Fa tor
Range 2 mV/div to 5 V/div in 1-2-5 sequen e?
A ura y (in ludes
ADD MODE and CH 2
INVERT)
15°C to 35°C Within ±2%.
-10°C to 15°C
and 35°C to 55 °C Within + 3%.a
Variable Range In reases defle tion fa tor by at least 2.5:1.
Frequen y Response
(-3 dB bandwidth)
2 mV/div to 5 V/div D to 100 MHz (at the input BNC and with a 10X probe).
AC Coupled Lower
-3 dB Point
IX Probe 10 Hz or less.
10X Probe 1 Hz or less.
Step Response (5-division
step)
Rise Time
2 mV/div to 5 V/div 3.5 ns or less ( al ulated).3
Aberrations
Positive-Going Step
5 mV/div to
0.5 V/div +5%, -5%, 5% p-p or less.
1 V/div to
5 V/div +10%, -10%, 10% p-p or less.
Negative-Going Step Add 2% to all positive-going step
spe ifi ations.
Position Effe t Aberrations measured anywhere on s reen
do not ex eed those measured at enter s reen by more
than 1%.
Temperature Effe t Add 0.15% per °C above or below 25°C.
Performan e Requirement not he ked in manual.
1-3

Specific tion—2246 1Y nd 2246 Mod A Service
T ble 1-1 (cont)
Electric l Ch r cteristics
Ch r cteristics Perform nce Requirements
Delay Mat h (CH 1 to CH 2) Less than 400 ps differen e.
Common Mode Reje tion
Ratio (CMRR) At least 25:1 up to 10 MHz and at least 10:1 up to 100 MHz
for signals of eight divisions or less with VOLTS/DIV VAR
adjusted for best CMRR at 50 kHz.
Channel Isolation
(attenuation of
desele ted hannel)
2 mV/Div to 0.5 V/Div
10 MHz 100 MHz
50 dB (= 316:1)
or more 34 dB ( = 50:1) or more
Channel isolation tested with eight-division input signal.
Tra e Shift as VAR
VOLTS/DIV is Turned 1 division or less.
Invert Tra e Shift 1 division or less.
Tra e Shift Between
VOLTS/DIV Swit h Positions 0.2 division or less.
Tra e Shift Between GND
and DC input Coupling
-10°C to 35°C Less than 0.5 mV.
35° C to 55 °C Less than 2 mV.a
Input Chara teristi s
Resistan e 1 M fl ±2%.a
Capa itan e 20 pF ±2 pF.a
Capa itan e Mat h
Between Any Two
VOLTS/DIV Settings + 0.5 pF.
Maximum Input
Volts / \ \ 400 V (d + peak a ); 800 V p-p at 10 kHz or less;
800 V p-p at 10 kHz or less; 5 V (d + peak a ) at
100 MHz or less.3
a Performan e Requirement not he ked in manual.
1-4

Specific tion—2246 IV nd 2246 Mod A Service
T ble 1-1 (cont)
Electric l Ch r cteristics
Ch r cteristics Perform nce Requirements
VERTICAL DEFLECTION SYSTEM - CH 3 AND CH 4
Defle tion Fa tor
Range 0.1 V per division and 0.5 V per division.3
A ura y
15°C to 35°C Within ± 2%.
-10°C to 55°C Within ±3%.
Frequen y Response
(-3 dB bandwidth) D to 100 MHz (at the input BNC and with a 10X probe).
Step Response (5-division step)
Rise Time 3.5 ns or less ( al ulated).3
Delay Mat h (CH 3 to CH 4) Less than 400 ps differen e.
Tra e Shift Between
VOLTS/DIV Settings 1 division or less.
Channel Isolation
(attenuation of
desele ted hannel)
34 dB or more at 100 MHz.
Channel isolation tested with eight-division
input signal.
Input Chara teristi s
Resistan e 1 M fi ±2%.3
Capa itan e 20 pF ±2 pF.a
Maximum Input
Volts A 400 V (d + peak a ); 800 V p-p at 10 kHz or less; 800 V p-p at 10 kHz or less; 5 V (d + peak a ) at
100 MHz or less.3
Performan e Requirement not he ked in manual.
1-5

Specific tion—2246 1Y nd 2246 Mod A Service
T ble 1-1 (cont)
Electric l Ch r cteristics
Ch r cteristics Perform nce Requirements
VERTICAL DEFLECTION SYSTEM - ALL CHANNELS
Bandwidth Limit
(-3 dB bandwidth) 20 MHz ±25%.
Low Frequen y Linearity
(Relative to
enter s reen) Within ±5%.
Linearity is measured by positioning a two-division test signal
anywhere on s reen and noting the amplitude hange.
Position Range At least ±10 divisions form grati ule enter.
TRACE SEP Control
Position Range At least ± 4 divisions.
CHOP Mode Clo k Rate 625 kHz ±10%.a
Delay Mat h (CH 1 or CH 2
to CH 3 or CH 4) Less than 800ps differen e.
HORIZONTAL DEFLECTION SYSTEM
Sweep Range
A Sweep 0.5 s/div to 20 ns/div in a 1-2-5 sequen e.3
X I0 magnifier extends maximum sweep speed to 2 ns/div.
B Sweep 5.0 ms/div to 20 ns/div in a 1-2-5 sequen e?
X I0 magnifier extends maximum sweep speed to 2 ns/div.
A ura y
15°C to 35°C
Unmagnified Magnified
±2% ±3%
-10°C to 15°C
and 35°C to 55°C ±3% ±4%
Sweep A ura y applies over the enter eight
divisions. Ex ludes the first 1/4 division or
25 ns from the start of the magnified sweep
and anything beyond the 100th magnified
division.
Performan e Requirement not he ked in manual.
1-6

Specific tion—2246 1Y nd 2246 Mod A Service
T ble 1-1 (cont)
Electric l Ch r cteristics
Ch r cteristics Perform nce Requirements
Sweep Linearity ± 5%.
Sweep Linearity applies over the enter eight divisions of
an unmagnified sweep. Ex ludes the first 1/4 division or
25 ns from the start of the sweep.
Sweep linearity is determined by the error of a single time
mark relative to two adja ent time marks spa ed at one
time mark per division.
POSITION Control Range
Normal Displays Able to move the start of the sweep to the right of the
enter verti al grati ule; able to move a time mark
orresponding to the end of the tenth division of an
unmagnified sweep to the left of the enter grati ule.
X-Y Displays At least ±13 divisions.3
X I0 Magnifier Expands the normal sweep by ten times around that portion
of the sweep positioned at the enter verti al grati ule line.3
Registration (XIOtoXI) 2 divisions or less shift.
Variable Control Range Continuously variable between alibrated SEC/DIV settings.
Extends both the A and B sweep time per division by at least
a fa tor of 2.5.
Sweep Length Greater than 10 divisions.
Delay Time
Delay Control Range Less than 0.1 division to 10 times the A SEC/DIV swit h
setting. Maximum value does not ex eed end of the A sweep.
Jitter 1 part in 20,000, or less, peak-to-peak, during a two-
se ond time interval.
Delta Time
Delta Control Range From 0.5 division or less to the right of setting
of DELAY ontrol to within 1.5 divisions of the
end of the A sweep.
a
1-7
Performan e Requirement not he ked in manual.