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