HP 1331A Service manual

U PERATI l\IG AND S E RVIC E MANUAL
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ODEL 1331A
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_,_.. -Y D IS PLAY

CERTIFICATION
Th e He wlett-Packard Company certifies that this instrument was
thoroughly tested and inspected and found to meet its published
specifications wh
en it was shipped from the factory. Th e Hewlett-
Packard Company further certifies that its calibration measure-
ments
are traceabl e to the U.S. National Bur eau of Standards to
the extent allowed by the Bur eau's calibration facility.
WARRANTY AND ASSISTANCE
This Hewlett-Packard product is warranted against defects
in materials and workmanship. This warranty applies for
one year from the date of delivery, or, in the case of certain
major components listed in the operating manual, for the
specified period. We will repair or replace products which
prove to be defective during the warranty period provided
they are returned to Hewlett-Packard. No other warranty
is expressed or implied. We are not liable for consequential
damages.
" '
Service contracts or custoµier assistance agreements are
available for Hewlett-Pa~kard products that require main-
tenance and repair on-site.
For any assistance, contact your nearest Hewlett-Packard
Sales and · S~rvice Office. Addresses are provided at the
back of this manual.
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OPERATING AND SERVICE MANUAL
MODEL 1331A
X-V DISPLAY
SERIALS PREFIXED: 1319A
Refer to Section VI I for instruments wit h other Serial Prefi xes.
Refer to Section VII for instruments with the following
standard options:X95,631.
HEWLETT-PACKARD COMPANY/COLORADO SPRINGS DIVISION
1900 GARDEN OF THE GO DS ROAD , COLORADO SPRINGS , CO LORADO , U.S .A.
ManualPartNumber01331-90903.
MicrofichePartNumber01331-90803.
PRINTED: MAY 1973

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Table of Co ntents
Model 1331A
TABLE OF CONTENTS
Section P
age
I
II
III
IV
11
GENERAL INFORMATION ..... . .. .... . 1-1
1-
1. Introdu ction . . . . .. . . . .. . . . . .. . . .. 1-1
1-
4. Description . . . . . . . . . . . . . . . . . . . . . . 1-1
1-10. Cathode-ray Tube ................ 1-1
1-1
2. Warranty .... .... ............ ... . 1-1
1-14. Available Accessories. . . ... . .... . 1-1
1-16. Instrument and Manu al
Identifi
cation . . . . . . . . . . . . . . . . . . 1-1
1-20. Inquiries. ........ .. ... . .......... 1-3
INSTALLATION. .... .. ... . .... .. ... . ... 2-1
2-1. Introdu ction .................... .
2-3 . Initial Inspection ............... .
2-5 . Preparation for Use .. . .... . ... . . .
2- 7. Rack Mounting ........... .. .. .
2-9. Power Re quirements ....... . .. .
2-11. Power Connections ............ .
2-13.
Instrum e nt Cooling ........... .
2-17. Monitored Inputs ........... . . .
2-19. Amplifier Input Modifications . .
2-34. Claims . ....... ... .............. . .
2-36. Repacking for Shipm e nt ... . .... .
OPERATION ... .... .. ... . ......... . .... .
3-1. Introduction ... .. ..... . .. . . .... . .
3-3. Controls and Connectors . ....... .
3-5. Beam Find . ... ................ .
3
-7. Intensity ..................... . .
3-9. Applications ..... . ......... . .... .
3-11. Preoperational Adjustments and
Operator's Checks . .. ........ . .
3-13. Operator's Maintenanc e ... .. .. .. .
3- 15. Operating Procedur es ........... .
PRINCIPLES OF OPERATION ....... . . .
4-1. Introdu ction .................... .
4-3. Variable Persistence and Storage .
4-5. The Storage CRT ............. .
4-10. Secondary
Emission Ratio . .. . .
4-
12. Erase Cycle ................... .
4-15 . Variable Persistence . . .... . ... .
4-19 . Storage ....... ... . .... . ....... .
4-21. Storage Precautions ... . ....... .
4-23. Block
Diagram Discussion ..... .
4-25. Low Voltage Power Supplies . . .
4-27. High Voltage Power Supply ... .
2-1
2-1
2-1
2-1
2-1
2-1
2-1
2-1
2-2
2-5
2-5
3-1
3-1
3-1
3-1
3-1
3-2
3- 2
3
-2
3-2
4-1
4-1
4-1
4-1
4-1
4-1
4-2
4-2
4-2
4 -2
4 -2
4-2
Section
Page
v
4-29.
4-31.
4-33.
4-35.
4-37.
4-54.
4-56.
4-64.
4-71.
4-76.
4-78 .
4-82.
X- and Y-axis Amplifiers . . . .. . . 4-2
Z-axis Amplifier . . . . . . . . . . . . . . . 4-3
Int e nsity Gat e . . . . . . .. . . . .. . . . . 4-3
Control Circuits................ 4-3
Pulse Circuits .. . . . . . . . . . . . . . . . . 4-3
Detailed Circuit Theory . . . . . . . . . . 4-4
Low Voltage Power Supp li es . . . 4-4
High Voltag e Power Supply . . . 4-5
X- and Y-axis Amplifiers ......... 4-5
Z- axis Amplifier . . . . . . . . . . . . . . . 4-5
Control Circuits . . . . . . . . . . . . . . . . 4-5
Pulse Circuits. . . . . . . . . . . . . . . . . . 4-6
PERFORMANCE CHECKS AND
ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . 5 -1
5- 1. Introduction . . . . . . . . . . . . . . . . . . . . . 5-1
5 -5. Performance Check . . . . . . . . . . . . . . 5 -1
5-8. Mode and Erase Checks. . . . . . . . 5- 2
5- 12. Deflection Checks.......... .... 5 -2
5- 16. Phase Shift Check . . . . . . . . . . . . . 5-2
5-2
0. Common Mode Rejection Ratio
(CMRR) Check . . . . . . . . . . . . . . . 5-2
5-2
4. Bandwidth Checks . . . . . . . . . . . . . 5 -3
5-28. Z-axis Amplifier Checks. . . . . . . . 5 -3
5-32. Erase Time Check . . . . . . . . . . . . . 5-4
5-3
6. Dot Writing Time Check . . . . . . . 5-4
5-40. Store Time Check . . . . . . . . . . 5-5/5-6
5 -44. Adjustment .... . . .. .... . ..... .... 5 -7
5-47. Low Voltag e Power Supply
Adjustments . . . . . . . . . . . . . . . . . 5-7
5-5
1. High Voltage Power Supply
Adjustment.. ............. .. . 5-7
5-55. Write Depth
Adjustment . . . . . . . 5- 7
5;5 9. Flood Gun a nd Collimator
Adjustments . . . . . . . . . . . . . . . . . 5 -8
5-63. Write Gun Intensity Limit
Adjustment . . . . . . . . . . . . . . . . . . 5 -8
5-67. X- and Y-axis Amplifier Gain
Adjustment ............... . .. 5-8
5- 71. Phase Shift Adjustment . . . . . . . . 5-8
5
-75. Writing Rate Adjustment ....... 5 -9
5-79. Store Time Adjustment.. . . ..... 5 -9
5-83. Z-a xis Amplifier Risetime
Adjustment. . . . . . . . . . . . . . . . . 5-10
5-87. Calibrating Modified
Instruments . . . . . . . . . . . . . . . . . . 5- 10
5-89. Phase Shift. ........ . ......... 5-10
5 -91. Attenuator Compensation..... 5-10
5-93. Input Signal Amplitudes . . . . . . 5-11

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Model 1331A
Table of Contents
List of Illustrations
TABLE OF CONTENTS (Cont'd}
Section
Page
VI
REPLACEABLE PARTS
6-1
6-1. Introduction . . . . . . . . . . . . . . . . . . . . . 6-1
6-3. Ordering Information . . . . . . .. . . . . 6-1
VII MANUAL CHANGES AND
OPTIONS......................... 7-117-2
7-1.
7-3.
7-7.
7-11.
Introduction ................ .
Manual Changes ............ .
Special Options ............. .
Standard Options ........... .
VIII SCHEMATICS AND TROUBLE-
7-117-2
"7-117-2
7-117-2
7-117-2
SHOOTING .. .. .. . .. .... .. .. .. .. .. .. .. 8-1
8-1. Introduction . . . . . . . . . . . . . . . . . . . . . 8-1
8-3. Schematics . . . . . . . . . . . . . . . . . . . . . . 8-1
Section
8-8.
8-12.
8-15.
8-17.
8-20.
8-23.
8-25.
8-27.
8-30.
8-32.
8-34.
8-36.
8-38.
8-40.
8-43.
8-45.
8-47.
Page
Reference Designations . . . . . . . . . . 8-1
Component Locations ............ 8-1
Preventive Maintenance . . . . . . . . . 8-1
Mechanical Inspection . . . . . .. . . 8-1
Cleaning.... ................... 8-1
Switch Maintenance . . . .. . . . . . . 8-2
Repair and Replacement . . . . . . . . . 8-2
CRT Removal and Installation . 8-2
Semiconductor
Removal and
Replacement..... ............ 8-3
Circuit Boards . . . . . . . . . . . . . . . . . . . 8-3
Board Connections. . . . . . . . . . . . . 8-3
Servicing Etched Circuit
Boards ....................... 8-3
Heat Sinks... .................. 8-3
Troubleshooting . . . . . . . . . . . . . . . . . 8-3
DC Voltages ................... 8-3
Waveforms
.. .. .... .. . .. .... .. . 8-3
Trouble Isolation. . . . . . . . . . . . . . . 8-3
LIST OF ILLUSTRATIONS
Figure Title Page
1-1.
Model 1331A X-Y Display ......... .... 1-0
1-2. Instrument Serial Number ............
1-3
2-1. Rack Mounting .......................
2-1
2-2. Ventilation Tolerances ............... .
2-2
2-3. X-Y Amplifiers Input Circuit ..........
2-4
2-4. Attenuator Components Locations on
Main Board A5 .....................
2-4
3-1.
Model 1331A Contro ls and Con-
nectors
............................. 3-3
3-2.
Preoperational Procedure ..............
3-4
3-3.
Genera l Operating Procedure ..........
3-5
3-4.
Multiple Display Procedure ............ 3-6
4-
1.
CRT Schematic ....................... 4-3
4-2. Secondary Emission Ratio
............ 4-3
4-3. Erase Cycle ...........................
4-3
4 -4.
Variabl e Persistence Pulsing .......... 4-3
4-5. Pulse Circuits Block Diagram .........
4-5
4-6. Overall Block Diagram ............
4-7 / 4-8
5-1.
Phase Shift Tr ace ..................... 5-3
5-2.
Erase Waveform ...................... 5-4
5-3. Write Depth Waveform ................
5-7
5-4. Adjustment Locator ............... 5-11/5-12
8-1. Al Component Locator ................ 8-4
8-2. A2 Component Locator ................ 8-5
Figure
8-3.
8-4.
8-5.
8-6.
8- 7.
8-8.
8-9.
8-10.
8-11.
8-12.
8-13.
8-14.
8-15.
8-16.
8-17.
8- 18.
8-19.
8-20.
8-2 1.
8-22.
Titl e
Page
Schematic, ±50 V Power Supplies 8-5
Semiconductor
Terminal Iden-
tification. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
Schematic, +158V and +12.6V Power
Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-7
A3 Component Locator ................ 8-8
A4
Component Locator. . . . .. . . . . . .. . . . 8-8
A7
Component Locator. . . . . . . . . . . . . . . . 8-8
Schematic 3 Measurement Conditions
and Waveforms............ .... 8-9/8-10
Schematic, High Voltage Power
Supply .......................... 8-9/8-10
Schematic 4 Measurement Conditions
and Waveforms. .............. 8-1118-12
Schematic, X- and Y-axis
Amplifiers . . . . . .. . . . . .. . . . .. . . . 8-11-8-12
Schematic 5 Measurement Conditions
and Waveforms... ................. 8-13
Schematic , Z-axis Amplifier ......... . 8-13
A6 Component Locator............... 8-14
A8 Component Locator............... 8-15
Schematic, Control Circuits . . . . . . . . . . 8-15
A5
Component Locator ............... 8-16
Schematic,
Pulse Circuits . . . . . . . 8-17/8-18
Write Mode Troubleshooting
Guide......................... 8-19/8-20
Store Mode Troubleshooting
Guide. . . . . . . . . . . . . . . . . . . . . . . . . 8-21/8-22
Erase Function Troubleshooting
Guide.............................. 8-23
111

List of Tables
lV
LIST OF TABLES
Table Title Page
1-1. Specifications......................... 1-2
1-2. Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
1-3. Reference Designations and
Abbreviations....................... 1-3
2-1. X-Y Attenuator Component
Values............ .................. 2-3
2-2. Attenuator Components Parts List . . . . 2-3
2-
3. Z-attenuator Component Values .. . . . . . 2-3
3-1. Definitions............................ 3-1
5-1. Recommended Test Equipment........ 5-1
Performance Check Record . . . . . . 5-6a/ 5-6b
5-2. Low Voltage Power Supply
Adjustments . . . . . . . . . . . . . . . . . . . . . . . . 5-7
6-1. Abbreviations for Replaceable
Parts List........................... 6-1
6-2. Replaceable Parts . . . . . . . . . . . . . . . . . . . . . 6-2
6- 3. List of Manufacturer's Codes.... 6-11 /6-12
8-1. Schematic Notes...................... 8-6
Model 1331A
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Genera l I nformation
Model 1331A
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1331A-A-7
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Figure 1-1. Model 1331A X-Y Display
1-0

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Model 1331A General Information
SECTION I
GENERAL INFORMATION
1-1. INTRODUCTION.
1-2. This manual provides operating and servicing
information for the Hewlett-Packard Model 1331A
X-Y Display (figure 1-1). The manual is divided into
eight sections, each covering a specific topic or as-
pect of the instrument. All schematics are lQcated at
the rear of the manual and can be unfolded and
used for reference while reading any part of the
manual.
1-3. This section contains a description of Model
1331A.
The instrument specifications are listed in
table 1-1. Table 1-3 lists and describes the abbre-
viations used everywhere in this manual except in
Section VI. The parts list in Section VI is a com-
puter printout and uses computer-supplied abbrevia-
tions. Special accessories are listed in this section.
Standard options available for this instrument are
listed and described in Section VIL
1-4. DESCRIP TI ON.
1-5. Model 1331A has been designed for general-
purpose X-Y storage and system monitoring. It can
display digital or analog computer-processed data or
real time information. Its high frequency response
makes it useful as a read-out device in the following
applications:
graphic and alphanumeric displays,
nuclear spectrometer, semiconductor curve tracer,
swept-frequency
measurements, frequency ratios,
phase shift measurements, raster displays , and ampli-
tude versus time displays.
1-6. Identical X and Y amplifiers provide storage
monitor displays with bandwidths up to 1 MHz. Re-
fresh memory requirements are minimized by the
mesh type storage CRT.
1
-7. All controls required to compensate for spot
deflection and dot writing speed are located on the
front panel. These include FOCUS , INTENSITY, PER -
SISTENCE, mode (WRITE, and STORE), POSITION
controls, and ERASE.
1
-8. Model 1331A writes and stores shades of gray
which adds a third dimension to the display. Spot
blanking is obtained with-IV. Maximum brightness
is obtained with +1V. In-between voltages provide
shades of gray.
1 -9 . Model 1331A is proportioned to permit mount-
ing two instruments (any HP 1330/1331-series instru-
ments) side-by-side in a standard 19-inch rack. Refer
to
the paragraph on available accessories in this
section for a description of a suitable rack adapter.
1-10. CATHODE-RAY TUBE.
1-11. Model 1331A uses a post-accelerator storage
CRT with a 10.5 kV accelerating potential and alum-
inized P31 phosphor. The 8 x 10 division internal
graticule is located on the same plane as the display
to eliminate parallax errors. The mesh type storage
used eliminates the need for memory devices to con-
stantly refresh the display. Refer to table 1-1 for
complete
CRT specifications.
1-12. WARRANTY.
1-13. The instrument (except the CRT) is certified
and warranted as stated on the inside front cover
of this manual. The CRT is covered by a separate
warranty. The CRT warranty and warranty claim
form is located at the rear of this manual. Shou ld
the CRT fail within the time specified on the CRT
warranty page, complete the warranty claim form and
return it with the defective CRT. The procedure for
returning a defective CRT is described on the CRT
warranty page.
The warranty may be void for instru-
ments having a mutilated seria l number
tag.
1-14. AVAILABLE ACCESSORIES.
1-15. Accessories availab le for use with Model 1331A
are listed in table 1-2. Hewlett-Packard also has
a wide range of test equipment and accessories suit-
able for use with HP instruments and instruments
of other manufacturers. Refer to the latest HP Catalog
or request information from the nearest HP Sales /
Service Office.
1- 16. INSTRUMENT AND MANUAL IDEN-
TIFICATION.
1-17. This manual applies directly to Model 1331
instruments with a serial prefix number as listed
on
the manual title page . The serial prefix number
is the first group of digits in the instrument serial
number (figure 1-2). The instrument serial number
is on a tag located on the rear panel.
1-1

General Information
Model 1331A
Table 1-1. Specifications
VERTICAL AND HORIZONTAL AMPLIFIERS
BANDWIDTH: de to 1 MHz (3 dB down at 1 MHz).
PHASE SHIFT: <1 ° to 0.5 MHz.
SETTLING TIME : Signa l settles to within 1 spot di-
ameter of final va lue in <1 µsec for any on-
screen movement.
DEFLECTION FACTOR
Vertlcal: 1V
for 8 div deflection. In terna ll y ad-
justable from 0.09 V/ div to 0.14 V/ div.
Horizontal: 1V for 10 di v deflection. Internally
ad ju stable from 0.09 V/ div to 0.14 V/ div.
COMMON MODE REJECTION RATIO: 40 dB to 10
kHz for differential input of 3V m aximum be-
tween outer and inn er coaxia l input l ea ds.
MAXIMUM INPUT: ±5 0V (de + peak ac).
INPUT: differentia l between center conductor and
shie ld, shield may be gro und ed wi th internal
connection.
INPUT RC
Single Ended: lOOk ohms s hun ted by approx 80
pF to ground.
Differential: 200k ohms sh unt ed by approx 80 pF.
RECOMMENDED SOURCE IMPEDANCE: <20ko hms
between ce nter conductor and shield; < lk ohm
from shield to ground.
Z AXIS AMPLIFIER
BANDWIDTH : de to >5 MHz; risetime, approx 70 ns.
INPUT RC
Single Ended: lOk ohms shunted by approx 60 pF
to ground.
Differential: 20k ohms sh un ted by approx 60 pF.
IN PUT: -1 Vb lanks spot of any in tensity;+1V turns
beam full on.
MAXIMUM INPUT: ±lOV (de + peak ac).
RECOMMENDED SOURCE IMPEDANCE: <20k
ohms
between center conductor and shield; <lk ohm
from shie ld to ground.
CATHODE-RAY TUBE AND CONTROLS
1-2
TYPE: post-accelerator storage tube 7.5 kV acce l-
era ting potentia l, al uminized P31 phosphor.
GRATICULE: 8 x 10 div internal graticule. 1 div=
0.95 cm. Subdivisions of 0.2 div marked on major
axis.
WRITING SPEED: >20
div / ms.
DOT WRITING TIME: <4 µsec.
DISPLAY LINEARITY
Horizontal: <5% difference between any two div.
Vertical: <5% difference between any two div.
INFORMATION STORAGE RATE : 200 thousand
dots per seco nd .
BRIGHTNESS: >100 foot lamb erts.
STORAGE TIME
Writing Mode: 1 minute min.
Store Mode:15 minutes min .
VARIABLE PERSISTENCE: variable from 0.2 secto
1 min.
ERASE TIME : <l sec.
BEAM FINDER : returns beam to screen regardless
of setting of X and Y position con trols. Rear
panel switch.
GENERAL
POWER : 115V or 230V ±10%, 48 to 440 Hz, approx
60W.
WEIGHT: net, 19-112 lb (8,85 kg); shipping, 25 lb
(11,34 kg).
DIMENSIONS: Refer to outline drawing.
NOTE1
DMC"'StONS I~ hCHES .6.ND().ILLY.ETfRS.I
C>"'C~S ARC APPRQX• VA TE Jf MORE
~ATE OME...S10"fS "RE R£0v RCO ,
C ~TACT HEvri.LCTT·PACKAAO CO
TOP
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Model 1331A
1-18. Check
the serial prefix number of the instru-
ment. If the serial prefix number is different from
that listed on the title page of this manual, refer to
Section VII for instructions to adapt this manual for
proper instrument coverage.
1-19.
Errors in the manual are listed under errata
on an enclosed MANUAL CHANGES sheet (if any).
1-20. INQUIRIES.
1-21. Refer any questions regarding the manual, the
change sheet, or the instrument to the nearest HP
Sales /Service Office. Always identify the instrument
by model number, complete name, and complete
serial number in all correspondence. Refer· to the
inside rear cover of this manual for a world-wide
listing of HP Sales /Service Offices.
General Information
SERIAL PREFIX NUMBER
SERIAL SUFFIX NUMBER
COMPLETE SERIAL NUMBER
7000-A-22
Figure 1-2. Instrument Serial Number
Table 1-2. Accessories
CAMERA ADAPTER: Model 10366B adapter provides
mounting of a HP Model 195A, 197A, or 198A
camera.
DISPLAY CABLE, MODEL 10488A: provides intercon-
nection between
the display and the signal input
source. The cable has three color-coded coaxial
cables with three male BNC connectors on each
end for the x, y, and z inputs.
Length: approx 12 ft (3.6m).
FRAME ADAPTER: a 7-inch (18 cm) high panel which
allows two Model 1331's to be mounted side-
by-side
in a standard 19-inch (48 cm) rack.
FILLER PANEL: covers halfofa Frame Adapter when
only one Model 1331 is in a Frame Adapter.
Table 1-3. Reference Designators and Abbreviations
REFERENCE DESIGNATORS
A assembly
E misc. electrical part
p
plug
u
Integrated circuit
AT
attenuator,
F
fuse
PS =
power supply
(unrepairable)
resistive termination
FL filter
Q
transistor
v -
vacuum tube, neon
B motor, fan
H hardware
A resistor
bulb, photocell, etc.
BT battery
J Jack
VA
voltage regulator
c capacitor
K relay
RT
= thermistor
(diode)
CP coupling
L = inductor
s =
switch
w =
cable
CR diode
LS
speaker
T
transformer x
socket
DL delay line
M = meter
TB
terminal board
y =
crystal
OS device signaling (lamp)
MP mechanical part
TP
= test point
z
network
ABBREVIATIONS
A
ampere(s)
FET
field-effect
n
nano (1 o-
9)
rfl
=
radio frequency
amp I
amplifier(s)
transistor(s) nc normally closed interference
assy
assembly
no.
normally open
rms root mean square
amp ltd
amplitude
giga (10
9)
npn negative-positive-
rwv reverse working
G
negative
voltage
bd
board(s)
gnd
ground(ed)
ns
nanosecond
bp
bandpass
SCA
= silicon controlled
H
henry(ies)
-12
rectifier
-2
hr
hour(s)
p
pico (10 )
second(s)
c
centl (10 )
pc
printed (etched)
sec
c
carbon
HP
Hewlett-Packard
circuit(s)
std standard
ccw
counterclockwise Hz
hertz
pk peak
coax. coaxial
pnp
positive-negative-
trmr trimmer
coef
coefficient If.
intermediate freq.
positive
-6
com
common inti
internal
p/o
part of
u
micro (10 )
CRT
cathode..-ey tube
kilo (10
3)
p-p
peak-to-peak
usec microsecond
cw
clockwise k
prgm
program
-I
prv
= peak inverse
v
volts
d
decl (10 ) lb
pound(s)
voltage(s)
var variable
dB
decibel
lpf
low-pass filter(s)
PS
picosecond
-3
w/
with
ext
external m
mllli (10
6)
pwv
peak working
w/o
without
M
mega (10 )
voltage
wiv working inverse
F
farad(s)
ms
millisecond rf
= radio frequency
voltage
3/70
1- 3/ 1-4

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Model 1331A
Installation
SECTION II
INSTALLATION
2-1. INTRODUCTION.
2-2. This section conta ins instructions for performing
an in i tial inspection of Model 1331A. Insta ll ation
procedures and precautions are presented in step-
by-step order. The procedures for m ak ing a c laim for
warranty repairs and for repacking the insltument
for shipment are also described in this section.
2-3. INITIAL INSPECTION.
2-4. The instrument was inspected mechanically and
electrically before shipment. Upon receipt, inspect
it for damage that may hav e occurred in transit.
Check for broken knobs, bent or broken connectors,
and dents or scratc hes. If damage is found, refer to
the claims paragraph in this section. Retain the
packing material for possible future use.
2-5. PREPARATION FOR USE.
2-6. Model 1331A is shipped from the factory ready
for use as a bench instrument with specifications as
listed in Section I. The following paragraphs discuss
other mechanical and electrical configurations of the
instrument.
2-7. RACK MOUNTING .
2-8. Figure 2-1 shows how one or two instruments
can be mounted in a single rack adapter. If only
one instrument is to be rack mounted the extra mount-
ing opening in the rack adapter can be closed with
a filler panel. Refer to Section I for ordering infor-
mation on the rack adapter and filler panel.
•
1331A·A·S
Figure 2- 1. Rack Mounting
2-9. POWER REQUIREMENTS.
2-10. Model 1331A operates on either 115 Vac or
230 Vac ±10%, 48 to 440 Hz. All instruments are
shipped ready for 115 Vac operation unless spec i-
fically ordered for 230 Vac operation. To change from
one
voltage to the other, set the SELECTOR switch
to the voltage desired and install the appropriate
fuse in the fuseholder on the rear panel. Correct
fuse size is indicated above the fuseholder.
2-11. POWER CONNECTIONS.
2-12. Hewlett-Packard recommends that tlie instru-
ment panel and cabinet be grounded. Model 1331A
is equipped with a three-conductor power cab le that,
when connected to an appropriate receptacle, grounds
the instrument through the offset pin. The power jack
and mating plug of the powercord meet International
Electrotechnical Commission (IEC) safety standards.
To preserve this protection feature when operating
from a two-contact outlet, use a three-conductor to
two-conductor
adapter. Connect the adapter wire to
ground at the power outlet.
2-13. INSTRUMENT COOLING.
2-14. Model 1331A is adequately cooled by normal
air circulation. The instrument requires at least a 2-
inch clearance at sides and top and 5/ 8-inch at
bottom when mounted singly (figure 2-2A). When
mounted in this configurat ion, the maximum ambient
temperature must not exceed +55 degC.
2-15. When mount ed in pairs, the minimum clear-
ances shown in figure 2-2B must be provided. When
mounted in this configurat ion, the surface directly
beneath the instrument(s) must not be a heat source
and the maximum ambient temperature must not
exceed +45 degC.
2-16. The clearances indicated in figure 2-2 will
provide
adeq u ate ventilation if air is allowed to cir-
culate freely across all surfaces a nd the specified
maximum ambient temperatures are not exceeded.
Other mounting co nfigurations and environments may
require additional coo ling measures.
2-17. MONITORED INPUTS.
2-18 Input signals to be displayed are connected to
the X-, Y-, and Z-axis amp lifi ers through BNC con-
nectors on the rear panel. The impedance of signal
sources must be 20 kilohms or less. The impedanc e
2-1

Installation
T.
B
5111
1331A -A-1 1
Figure 2-2. Ventilation Tolerances
from
the BNC shield to ground must be less than 1
kilohm.
Inputs not in use should be shorted. This
can be done with a BNC shorting plug (HP Part
No . 1250 -077 4).
2-19. AMPLIFIER INPUT MODIFICATIONS.
2-20. Several modifications can be m ade to the X-,
Y-, and Z-axis amplifier input circuits. These circuits
can be connected for either differential or single-
ended operation. The input termination resistance
can be changed . The input attenuation ratio can
be changed. The modifications are described in the
following paragraphs.
2-21. Deflection Amplifier Inputs. The inputs
to the x- and y-axis amplifiers are through floating
BNC connectors, with the shield and center con-
ductor connected to the two inputs of a differential
amplifier.
Figure 2-3 is a simplified schematic
showing the configuration of one deflection amplifier
input. As shipped from the factory, Ra = Rb = 2.7n,
Re= 100 kn, and Rd = 47n. Ca; Cb, Cc, and Cd are
not installed but pads are provided on the circuit
board (see figure 2-4) for c ustomer installation. The
inputs can be modified to be fully differential and
balanced, both in impedance and sensitivity, com-
pletely single ended with shield grounded (A and
B on figure 2-4), or anything in between.
2-22. Single-ended Operations. When coaxial
cable
is used, large spurious currents may be gene-
2-2
Model 1331A
rated in the cable shield through capacitive or
inductive coupling and none, or very little, in the
center conductor. This is especially true where long
cables are used or where the cable is routed near
units drawing or generating large amounts of
current. One method of reducing the interference
is to ground the shield at the input. Sometimes,
however, a
common mode rejection capability is
needed to reject noise common to both the shield
and the center conductor. At other times, ground
loops may develop when the shield is directly
grounded.
In these cases, a satisfactory compromise
is accomplished by substituting a low value of resist-
ance for Rd. This is the input configuration (Rd= 47Q)
of Model 1331A as shipped from the factory.
2-23. Differential Operation. If the deflection
input is driven by a balanced cable, it is usually
better to maintain balanced impedances at the input;
that is, Re= Rd. As shipped from the factory, sub-
stituting a 100 kn resistor for Rd restores full differ-
ential balance.
2-24. X. and Y-axis Amplifier Attenuation .
As shipped from the factory, full sca le deflection
(8 divisions vertical and 10 divisions horizontal) is
accomplished
with 1 volt input to X INPUT or Y
INPUT. The attenuation ratio can be changed by
changing the values of the attenuator components in
the input circuits. Figure 2-3 is a simplified schematic
showing the input circuit components and figure 2-4
shows their physical locations. Table 2-1 lists the
components required for four common attenuation
ratios. Table 2-2 contains a description of the com-
ponents and their Hewlett-Packard part numbers .
NOTE
The 2.7 ohm resistor shown in figure 2-3
must be removed when Ra is used.
2-25. Resistor values for attenuation ratios not
listed in table 2- 1 can be determined from the fol-
lowing formula:
Ra+ Re
Vfsd = Re
Resistor
spacing on main assembly A5 is
for 1 /i W, 1 %, metal film resistors. If
Ra + Re is less than 5 kilohms, the
maximum input voltage must be re-
duced b eca use of resistor power dissi-
pation limitations.

Model 1331A
General In format ion
Table 2-1. X-Y Attenuator Component Values
(
vfsd
Approximate Input
Impedance
Full-Scale R
a, Rb
Re, Rd
Ca, Cb Cc, Cd
Deflection
Voltage
1 (as shipped) 0 100k 0 0 100k
2 51.1k
51.1 k 5.5-18 pF 0 102.2k
5
82 . 5k 20k 5.5-18 pF 33 pF 102.5k
10
90. 9k f Ok 0 0 100.9k
Table 2-2. Attenuator Components Par ts List
Description
HP Part No .
R: fixed, metal film, 100k, 1% 1/2W 0757-0367
R: fixed, metal film, 82.5k ohms, 1% 1/2W 0757-0048
R: fixed, metal film, 51.1k ohms, 1% 1/2W 0757-0853
R: fixed, metal film, 20k ohms, 1% 1/ 2W
0757-0190
R: fixed, metal film, 10k ohms, 1% 1/ 2W
0757-0839
R: fixed metal film, 10k ohms, 1%, 1 /8 W 0757-0442
R: fixed, metal film, 9090 ohms, 1%, 1/ 8W
0757-0288
R: fixed, metal film, 5110 ohms, 1%, 1/ 8W
0757-0438
R: fixed, metal film, 1000 ohms, 1% 1/8W 0757-0280
R: fixed, metal film, 100 ohms, 1%, 1/8W 0757-0401
C: variable, 5-5 -18 pF 0121-0061
C: variable 9-35 pF
0121-0046
C: fixed, 33 pF 0160-2150
Table 2-3. Z-attenuator Component Values
Vmax R173 R175
cc
Approximate
R174 R182
Input
Impedance
1 (as
1oon 10K 0
10. lK
shipped)
:c 2 5110Q 5110Q
9-35 pF 10.22K
10 9090Q
1ooon 0 10.
09K
2-3

Install a tion
2 -4
Ca
2.1
CENTER
A
i
Ra
Re
Cc
C•
2.7
SHIELD
B
i
Rb
Rd
Cd
-=
Figure 2-3. X-Y Amplifie rs Input C ircuit
c 2.7
C> Cc E>~
~ R8 --0 D ~
dA D CJ
"'~--;JJ o"o
': .-t:~~~~ , o~ §~00
:i ·? ~ ~o=~
~ · ~?~~ != 00=
~ ~,,~t l2a ~:o
2.7
Figure 2-4. Attenuator Components Locationson Main Board A5
Model 1
33 1A
1331A-A-10
1331A-A-8 )

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Model 1331A
2-26. The approximate value, in picofarads, of com-
pensation capacitor Ca can be determined from
the following formula:
2-27. If practical values of ca cannot be attained
from the formula in par agrap h 2-25, add shunt
capacitor Cc and use th e following formula to
recalculate Ca:
2-28. Z-axis Amplifier Attenuation. The at-
tenuation ratio of the input circuit of the z-axis am-
plifier ca n be changed by changing the values of
A5R90 or A5Rl 74 and A5Rl82 or all four if differ-
entia l input is required. Three common attenuation
ratios are listed in table 2-3. Other values can be
calculated with the following formula:
V _
Rl82 + R174
max - Rl82
2-29. If the ratio of Ra to Rb is between 0.1
and 10, compensation capacitor Cc may be re-
quired. If required, use the following formula:
Rl82
c = ---
c 13 Rl74
NOTE
Vmax is the voltage that will produce
full
intensity or blanking (depending on
polarity).
2-30. Termination imp edance. The input term-
ination resistance of the x- and y-axis amplifiers is
normally 100 kilohms single ended and 200 kilohms
differential. The z- axis amp lifi er is 10 kilohms single
ended and 20 kilohms differential. The termination
resistance can be changed by eith er of two methods:
changing attenuation resistors, or conn ecting a third
resistance between input and ground. The second
method is simple because it does not c hang e the
attenuation ratio. Because of design considerations,
the second method ca nnot be us ed on the z-axis
amp lifier.
2-31. When changing attenuation resistor values to
get a certain termination impedance, two things must
be considered: the termination impedance and the
Installation
attenuation ratio. For example, when a 75-ohm term-
ination and a 5:1 ratio are required, the resistance
values are: Ra = 60 an d Re = 15 (A5Rl 74 and
A5Rl 75 respectively for the z-axis amplifier). The
information on compensation in the paragraphs on
x- and y-axis attenuation applies here, but com-
pensation may not be required when Ra and RC
have been changed to produ ce a low termination
impedance (< l kilohm ).
2-32. When shunting a resistance across the am-
plifier input to change (lower) the impedance , the
main consideration is the desired impedance . Select
a
resistor a nd insert it between the amplifier input
and ground (point A on figures 2-3 and 2-4). If less
than 10 kilohms are used, maximum input voltage to
the amplifier must be reduced because of resistor
power dissip ation limitations.
2-33. CLAIMS.
2-34. The warranty statement applicable to this
instrument is printed inside the front cover of this
manual. Refer to the rear of this manual for the CRT
warranty statement. If physical damage is found or
if operation is not as specified when the instrument is
received, notify the carrier and n earest HP Sales /
Service Office
immediately (refer to the list in back
of this manual for addresses). The HP Sales /Service
Office will
arrange for repair or replacement without
waiting for settlement of the claim with the carrier.
2-35. REPACKING FOR SHIPMENT.
2-36. If the Model 1331A is to be shipped to an
HP Sales /Service Office for service or repair, attach
a tag showing owner (with address), complete instru-
ment serial number , and a description of the service
required.
2-37. Use the original shipping carton and packing
material. If the original packing material is not
ava ilable, the HP Sales /Service Office will provide
information and recommendations. on materials to be
u
se d. Materials used for shipping an instrument nor-
mally include the following:
a. A double-walled carton of at least 275 pound
test strength.
b. Heavy paper or sheets of cardboard to pro-
tect all instrument surfaces; use a nonabrasive
material such as polyurethane or cushioned paper
such as Kimp ak a round all projecting parts.
c. At least 4 inches of tightly-packed, industry-
approved, shock-absorbing m ate rial such as extra-
firm polyurethane foam.
d. Heavy-duty
shipping tape for securing out-
side of carton.
2-5 /2-6

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Model 1331A Operation
SECTION 111
OPERATION
3-1. INTRODUCTION .
3-2. This section contains an explanation of Model
1331A op
era ting controls, mod es of operation, opera-
tor 's checks and adjustments, a nd step-by-step
opera
ting instructions. Table 3-1 co ntains a list of
words a nd phr ases used to d escr ibe the operation
of the instrument.
3-3. CONTROLS AND CONNECTORS.
3-4. All co ntrols and connectors are identified a nd
described in figure 3- 1. Controls requiring further
expl anatio n are covered in the following para gra phs.
3-5. BEAM FIND.
3-6. Th e BEAM FIND cont rol is a sli de switch us ed
to locate
the b eam when it is deflected off screen
due
to a la rg e input voltage, misadjustment of the
POSITION controls, or a malfunction. To operate
the BEAM FIND cont rol, pro ceed as follows:
a.
Set INTENSITY fully ccw.
b.
Set BEAM FIND to ON .
c. Turn INTENSITY slowly cw until beam is
visible.
d. D
ete rmin e action required to return beam
to vie wing area.
e. Set BEAM FIND to off. Model 1331A will
n
ot operate co rr ectly with BEAM FIND set to ON .
3-7. INTENSITY.
A high inten sity display over an extended
period
of time can ca u se burn damage to
th e CRT display area.
Table 3-1. Definitions
Word or Phrase Definition
Write To
transform an input signal into a visua l
display on the CRT.
Pers i stence The le ngth of time a displ ay remains on the
C RT after the writing signal h as be en re -
moved .
Store
To retain , for an extended period of tim e,
a
display that has been written on th e CRT.
Erase
To remove all displays and blooms th at have
been written or sto red on th e CRT.
Int ens ity The brightness of a displ ay written on th e
CRT.
Bloom Visible,
nonsymmetric al expansion and dis-
tortion
of a display written on the CRT.
Backgro und
A light-green illumination cove ring the en-
illumination
tire CRT viewing area.
Fade positive
An in crease in background illumination in-
tens
ity occuring in e ith er write or store mode.
Fade negative
A decrease in trace int ensity occuring in e ith er
write
or sto re mode.
3-1

Operation
3-8. The INTENSITY control adjusts the display in-
tens ity from completely off (ccw) to maximum bright-
ness (cw) in th e write mode. To avoid damage to the
CRT, follow the preoperational procedure in figure
3 -2 before operating the instrument . Increase intensity
slowly unti l the display brightness is at a comfortable
vie
wing level without blooming.
3-9. APPLICATIONS.
3-10. Model 1331A can be used for any application
of x-, y-, and z- axis displays within its bandwidth
and sensitivity specifications (refer to specifications
in Section I). Furthermore, the type of input (dif-
ferential or single ended), amplifier deflection factor,
: md amplifier input termination impedance can be
modified (Section II) to meet the requirements of
many specific applications. Refer to the description
paragraph in Section I for a l ist of su ggested app li-
cations.
3-11. PREOPERATION ADJUSTMENTS AND
OPERATOR'S CHECKS.
3- 12. The preoperational procedure is shown in
figure 3-2. This procedure also serves as an operator
check to verify proper operation of the instrument.
3-2
Model 1331A
3-13. OP E RA TOR'S MAINT ENANCE.
3 -14. Operator's maintenance of Model 1331A is
limited to
the ope rator 's checks in paragraph 3-12
and exterior cleaning of the instrument. Pull upward
on the contrast screen for removal and cleaning.
This exposes the face of the CRT for cleaning. Glass
surfaces and smooth metal surfaces can be cleaned
with a commercial glass cleaner. Stubborn residues
can be removed with a mi ld liquid household
detergent.
3-15. OPERATING PROCEDURES.
3- 16 . Fi gures 3-2 through 3-4 contain step-by-step
operating procedures. The index numbers on the
photographs correspond to step numbers in the
instructions. Only the basic operating techniques are
explained
in the illustrations. These techniques can
be modified or combined to fill a wide variety of
unique operating requirements.