HP 1740A Service manual

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OPERATING
AND
SERVICE
MANUAL
MODEL 1740A
OSCILLOSCOPE
(Including Options 001, 090, 101, 102, 900, 901,
902, and 903)
SERIAL NUMBERS
This
manual
applies
directly
to
instruments
with
serial
numbers
prefixed
1632A.
With
changes
described
in
Section
VII,
this
manual
also
‘|
applies
to
instruments
with
serial
numbers
prefixed
,
1522A
through
1616A.
For
additional
important
information
about
serial
num-
bers,
see
INSTRUMENT
AND
MANUAL
IDENTIFICA-
TION
in
Section
I.
HEWLETT-PACKARD
COMPANY/COLORADO
SPRINGS
DIVISION
1900
GARDEN
OF
THE
GODS
ROAD,
COLORADO
SPRINGS,
COLORADO,
U.S.A.
) Manual Part Number 01740-90909
Microfiche Part Number 01740-90809
PRINTED: AUGUST 1976

SAFETY SUMMARY
The
following
general
safety
precautions
must
be
observed
during
all
phases
of
operation,
service,
and
repair
of
this
instrument.
Failure
to
comply
with
these
precautions
or
with
specific
warnings
elsewhere
in
this
manual
violates
safety
standards
of
design,
manufacture,
and
intended
use
of
the
instrument.
Hewlett-Packard
Company
assumes
no
liability
for
the
customer's
failure
to
comply
with
these
requirements.
GROUND THE INSTRUMENT.
To
minimize
shock
hazard,
the
instrument
chassis
and
cabinet
must
be
connected
to
an
electrical
ground.
The
instrument
is
equipped
with
a
three-conductor
ac
power
cable.
The
power
cable
must
either
be
plugged
into
an
approved
three-contact
electrical
outlet
or
used
with
a
three-contact
to
two-contact
adapter
with
the
grounding
wire
(green)
firmly
connected
to
an
electrical
ground
(safety
ground)
at
the
power
outlet.
The
power
jack
and
mating
plug
of
the
power
cable
meet
International
Electrotechnical
Commission
(IEC)
safety
standards.
DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.
Do
not
operate
the
instrument
in
the
presence
of
flammable
gases
or
fumes.
Operation
of
any
electrical
instrument
in
such
an
environment
constitutes
a
definite
safety
hazard.
KEEP AWAY FROM LIVE CIRCUITS.
Operating
personnel
must
not
remove
instrument
covers.
Component
replacement
and_
internal
adjustments
must
be
made
by
qualified
maintenance
personnel.
Do
not
replace
components
with
power
cable
connected.
Under
certain
conditions,
dangerous
voltages
may
exist
even
with
the
power
cable
removed.
To
avoid
injuries,
always
disconnect
power
and
discharge
circuits
before
touching
them.
DO NOT SERVICE OR ADJUST ALONE.
Do
not
attempt
internal
service
or
adjustment
unless
another
person,
capable
of
rendering
first
aid
and
resuscitation,
is
present.
USE CAUTION WHEN EXPOSING OR HANDLING THE CRT.
Breakage
of
the
Cathode-ray
Tube
(CRT)
causes
a
high-velocity
scattering
of
glass
fragments
(implosion).
To
prevent
CRT
implosion,
avoid
rough
handling
or
jarring
of
the
instrument.
Handling
of
the
CRT
shall
be
done
only
by
qualified
maintenance
personnel
using
approved
safety
mask
and
gloves.
DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.
Because
of
the
danger
of
introducing
additional
hazards,
do
not
install
substitute
parts
or
perform
any
unauthorized
modification
to
the
instrument.
Return
the
instrument
to
a
Hewlett-Packard
Sales
and
Service
Office
for
service
and
repair
to
ensure
that
safety
features
are
maintained.
DANGEROUS PROCEDURE WARNINGS.
Warnings,
such
as
the
example
below,
precede
potentially
dangerous
procedures
throughout
this
manual.
Instructions
contained
in
the
warnings
must
be
followed.
Dangerous
voltages,
capable
of
causing
death,
are
present
in
this
instrument.
Use
extreme
caution
when
handling,
testing,
and
adjusting.
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Model
1740A
Table
of
Contents
TABLE OF CONTENTS
|
Section
Page
Section
Page
I
GENERAL
INFORMATION
..............
1-1
4-33.
Preamplifier
Stage
..............
4-2
4-41.
Preamplifier
Controls
...........
4-4
1-1.
Introduction
......................
1-1
4-53.
Delay
Line
Assembly
...........
4-5
1-5.
Specifications.....................
1-1
4-54,
Vertical
Output
Amplifier
.......
4-5
1-8.
Accessories
Supplied
..............
1-1
4-56.
Horizontal
Section
................
4-5
1-10.
Accessories
Available
.............
1-1
4-57.
Main
Trigger
Circuitry
..........
4-5
1-12.
Options..............000.......00.
1-1
4-64.
Main
Sweep
and
Integrator
.....
4-6
1-14.
Instrument
and
Manual
4-69.
Delayed
Trigger
Operation
......
4-7
Identification
.................
1-1
4-70.
Delayed
Sweep..................
4-7
4-71.
Horizontal
Display
Switch
IIT
INSTALLATION
.........................
2-1
Assembly
..............2..00...
4-7
4-76.
Horizontal
Preamplifier
.........
4-7
2-1.
Introduction
......................
2-1
4-79,
Horizontal
Output
..............
4-8
2-3.
Initial
Inspection
.................
2-1
4-80.
Gate
Amplifier
Assembly
.........
4-8
2-5.
Power
Cords
and
Receptacles
.....
2-1
4-88.
High-voltage
Power
Supply
.......
4-8
2-7.
Power
Requirements
..............
2-1
4-96.
Low-voltage
Power
Supply
........
4-9
2-10.
|
Repacking
for
Shipment
..........
2-1
4-98.
+15-volt
Supplies
................
4-9
4-101.
+5-volt
Supply.............0.....
4-9
III
OPERATION....................0..000...
3-1
4-102.
+120-volt
and
+43-volt
Power
Supplies
...............
4-9
3-1.
Introduction
......................
3-1
4-105.
Floodgun
Filament
Voltage
....
4-10
3-3.
Turn-on
Procedure
................
3-1
4-106.
Line
Frequency
................
4-10
3-5.
Operator
Checks
..................
3-1
4-107.
Option
101..............00.......
4-10
3-12.
Trigger
Selection
Table
.........
-.
&2
3-13.
Obtaining
Basic
Displays.........
3-2
V
PERFORMANCE
TESTS
AND
3-15.
|
Normal
Sweep
Display............
3-2
ADJUSTMENTS
.......................
5-1
3-16.
|
Magnified
Sweep
Display
.........
3-3
*»
3-17.
Delayed
Sweep
Display
...........
3-3
5-1.
Introduction
......................
5-1
3-18.
Mixed
Sweep
Display
.............
3-3
5-3.
Recommended
Test
Equipment....
5-1
3-19.
X-Y
Display.......0..0............
3-4
5-5.
Test
Record.................0..005.
5-1
3-20.
Single
Sweep
Operation
...........
3-4
5-7.
Performance
Tests
................
5-1
3-23.
Single
Sweep
Using
Trigger
5-9.
Initial
Control
Settings
...........
5-1
VIEW
Ket
Aone
ids
Baden
tate
catek
3-4
5-11.
Performance
Test
Procedures......
5-1
5-12.
Bandwidth......................
5-1
IV
PRINCIPLES
OF
OPERATION...........
4-1
5-15.
Common
Mode
Rejection
Ratio..
5-3
5-17.
Triggering
..................000.
5-4
4-1.
Introduction
......................
4-1
5-22.
Sweep
Time
Accuracy...........
5-5
4-3,
Vertical
Section
Block
Diagram...
4-1
5-24.
Differential
Time
Accuracy......
5-6
4-4,
Input
Attenuators...............
4-1
5-26.
Delay
Jitter.....................
5-6
4-5.
Vertical
Preamplifier............
4-1
5-28.
Rise
Time...................000.
5-7
4-6.
Delay
Line......................
4-1
5-30.
Z-axis
Blanking.................
5-7
4-7,
Vertical
Output
Amplifier
.......
4-1
5-32.
Deflection
Factor
...............
5-7
4-8.
Horizontal
Section
Block
5-34.
Calibrator
.................0.....
5-8
Diagram........................
4-1
5-36.
Adjustments
...................0..
5-8
4-9,
Trigger
Circuit..................
4-1
5-40.
Low-voltage
Power
Supply
4-11.
Sweep
and
Integrator
Circuit....
4-1
Adjustment
...................
5-8
4-13.
Holdoff
Circuit..................
4-1
5-41.
Intensity
Limit
Adjustment
.....
5-9
4-14,
Horizontal
Preamplifier
.........
4-1
5-42.
Astigmatism
and
Focus
4-15.
Horizontal
Output
..............
4-]
Adjustment
...................
5-9
4-16.
Gate
Circuitry
....................
4-1
5-43.
Gate
Response
Adjustment......
5-9
4-18.
High-voltage
Power
Supply
.......
4-2
5-44,
Floodgun
Grid
Adjustment
......
5-9
4-22.
Low-voltage
Power
Supply
........
4-2
5-45.
Trace
Align
and
Y-axis
4-25.
Circuit
Details
..........0.0.......
4-2
Align
Adjustments............
5-9
4-27,
Attenuator
Assemblies
............
4-2
5-46.
Trace
Align
and
Y-axis
Align
4-28.
General
Information
............
4-2
Adjustments
-
OPTION
101...
5-9
»
4-29,
Input
aceccs
cond
ee
ace
eins
lochs
4-2
5-47,
Calibrator
Amplitude
4-30.
Attenuator
Stages...............
4-2
Adjustment
...................
5-9
431.
Vertical
Section.
..................
4-2
5-48.
Trigger
Sensitivity
Adjustment.
5-10
4-32.
General
Information
............
4-2
5-49.
Sync
Zero
Adjustment
.........
5-10
il

Table of Contents Model 1740A
List of Illustrations
TABLE OF CONTENTS (Cont'd)
Section Page Section Page
5-50. Trigger View Balance 8-14. CRT Removal and Replacement. 8-2
Adjustment ................... 5-10 8-15. HV Power Supply Assembly
5-51. Delay Start Adjustment.......... 5-11 Removal and Replacement .... 8-3
5-52. Horizontal Amplifier Gain 8-16. HV Multiplier Assembly
Adjustments ................... 5-11 Removal and Replacement .... 8-3
5-53. X10 Amplifier Balance 8-17. LV Power Supply Assembly
Adjustment .................... 5-11 Removal and Replacement .... 8-3
5-54, Horizontal Linearity 8-18. Gate Amplifier Assembly
Adjustment .................... 5-11 Removal and Replacement .... 8-4
5-55.
Preliminary
Main
Sweep
8-19.
Vertical
Output
Amplifier
Calibration .................... 5-12 Assembly Removal and
5-56.
Delayed
Sweep
Adjustment
......
5-12
Replacement
..................
8-4
5-57.
Main
Sweep
Fine
Adjustment
....
5-12
8-21.
Vertical
Preamplifier
Assembly
5-58
Vertical
Amplifier
Balance
A3,
Delay
Line
Assembly
A4,
Adjustment
....................
5-13
and
Vertical
Control
Switching
5-59.
Position
and
Sync
Balance
Assembly
A13
Removal
and
Adjustment
....................
5-138
Replacement
..................
8-6
5-60.
Input
Capacitance
and
Attenuator
8-25.
Horizontal
Output
Assembly
Compensation
Adjustments
....
5-14
Removal
and
Replacement
....
8-7
5-61.
Vertical
Gain
Adjustment........
5-14
8-26.
Horizontal
Sweep
Assembly
5-62.
Pulse
Response
Adjustment
......
5-14
Removal
and
Replacement....
8-7
5-63.
X-Y
Gain
Adjustment
............
5-15
8-27.
Delayed
Trigger
Assembly
Removal and Replacement .... 8-7
VI REPLACEABLE PARTS ................. 6-1 8-28. Circuit Board Repairs............. 8-7
6-1. Introduction ...............00.000. 6-1 8-30. Board Connections.............. 8-7
6-3. Ordering Information ............. 6-1 8-31. Soldering ....................00. 8-7
8-32. Integrated Circuit
VII MANUAL CHANGES .................... 7-1 Removal and Replacement .... 8-8
8-33. Troubleshooting .................. 8-8
7-1. Introduction ...................... 7-1 8-36. Initial Troubleshooting
7-3. Manual Changes.................. 7-1 Procedure...............000005 8-8
8-37. De Voltages and Waveforms .... 8-8
VUI SCHEMATICS AND 8-38. Trouble Diagnosis .............. - 8-8
TROUBLESHOOTING ................. 8-1 8-39. LV Power Supply ............... 8-9
8-41. HV Power Supply............... 8-9
8-1. Introduction ...................0.. 8-1 8-47. Gate Amplifier.................. 8-9
8-3. Preventive Maintenance .......... 8-1 8-48. Vertical Section................ 8-10
8-4, Cleaning 62. ascii hk ew ses 8-1 8-51. Horizontal Output Amplifier ... 8-10
8-6. Switch Maintenance ............ 8-1 8-52. Time Base ...............000005 8-10
8-12, Removal and Replacement ........ 8-2
LIST OF ILLUSTRATIONS
Figure
Title
Page
Figure
Title
Page
2-1.
Types
of
Power
Source
Receptacles
4-1.
Vertical
and
Horizontal
Block
Diagram
4-3
and
Applicable
Input
Power
Cable
4-2.
LVPS,
HVPS,
and
Gate
Amplifier
Part
Numbers.....................00
2-1
Block
Diagram.......................
4-4
2-2,
Line
Voltage
Selection
4-3.
Gate
Schmitt
Simplified
Block
Diagram
4-7
Switch
Settings
......................
2-1
4-4,
Timing
Relationship
of
the
Gate
3-1.
Controls
and
Connectors...............
3-0
and
Sweep
Waveforms
...............
4-7
3-2.
Probe
Compensation
...................
3-2
4-5.
Gate
Control
Simplified
Block
Diagram
4-8
3-3. Normal Display.....................0.. 3-3
3-4. Magnified Display ..................... 3-3
3-5. Normal Display with Intensified Area.. 3-3 5-1. Bandwidth Test Setup ................. 5-3
3-6. Delayed Sweep Display ................ 3-3 5-2. CMRR Test Setup..................0005 5-3
3-7. Normal! Display with Intensified Area.. 3-4 5-3. External Triggering Test Setup......... 5-4
3-8. Mixed Sweep Display .................. 3-4 5-4, Pulse Response Adjustments .......... 5-15
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Model 1740A
Figure
5-5.
7-1.
7-2.
7-3.
7-4,
7-5.
8-1.
8-2.
8-3.
8-4.
8-5.
8-6.
8-7.
8-8.
8-9.
Table
1-1.
1-2.
3-1.
5-1.
5-2.
5-3.
5-4.
5-5.
5-6.
5-7.
List of Illustrations
List of Tables
LIST OF ILLUSTRATIONS (Cont'd)
Title Page
Adjustment Locations................. 5-23
Chassis Parts and Board Assembly
Identification .....................0.. 6-1
Replacement for Component Locator
in Figure 8-16.....................0.. 7-2
Replacement for Component Locator
in Figure 8-17..................000005 7-3
Replacement for Component Locator
in Figure 8-19 ..............0...00000. 7-4
Replacement for Component
Locator in Figure 8-10................ 7-6
Changes to Schematic 1................ 7-7
Rear-panel Changes.................... 7-7
Switch Extender Shaft Removal........ 8-1
CRT Removal................00 0c eee 8-2
Low-voltage Power Supply Removal.... 8-4
Gate Amplifier Assembly Removal ..... 8-5
Vertical Output Amplifier Removal..... 8-5
ASAI Removal.................00000 eee 8-5
AS8A1 Removal..............0 00. cece eee 8-7
Location of A7 Attaching Screws....... 8-7
Semiconductor Terminal
Identification ...................00005 8-8
Service Information, Low-voltage
Power Supply Assembly Al6........ 8-12
LIST OF TABLES
Title Page
Specifications ................0000 eee eee 1-2
General Information ................... 1-4
Display and Trigger Selection Table.... 3-2
Recommended Test Equipment......... 5-2
Main TIME/DIV Accuracy............. 5-5
Delayed TIME/DIV Accuracy.......... 5-6
Deflection Factor Accuracy............. 5-8
Low-voltage Supply Limits............. 5-8
Preliminary Main Sweep
Calibration .....................0005 5-12
Delayed Sweep Calibration
Adjustments .............0.000. 00008 5-12
Figure
8-11.
8-12.
8-13.
8-14.
8-15.
Table
5-8.
5-9.
6-1.
6-2.
6-3.
7-1.
8-1.
8-2.
8-3.
Title Page
Service Information, High-voltage
Power Supply Assembly Al5........ 8-14
Service Information, Gate Amplifier
Assembly Al2 .............0...0005. 8-16
Service Information, Vertical
Preamplifier Assembly A3 .......... 8-18
Service Information, Vertical Output
Assembly A5 ............. 000s 8-20
Service Information, Vertical Control
Switching Assembly A13 and Vertical
Preamplifier Assembly A3 .......... 8-22
Service Information, Main Trigger,
P/O Assembly A7............00000005 8-24
Service Information, Main Sweep
Assembly A& ........ 0.2.0.0. cee eee 8-26
Service Information, Delayed Trigger
Assembly Al0 and Horizontal Sweep
Assembly A7 ............000 000 eae 8-28
Service Information, Delayed Sweep
Assembly AQ ........... 00 cee eens 8-30
Service Information, Horizontal
Output Assembly All and Horizontal
Sweep Assembly A7................. 8-32
Service Information, Gate Schmitt,
P/O Assembly A7...............205- 8-34
Service Information, Interface
Assembly Al4 ........... 000000 cee 8-37
Service Information. OPTION 101
Interface Assembly Al4............. 8-38
Interconnection Diagram.............. 8-40
Title Page
Main Sweep Fine Adjustment ......... 5-18
Condensed Adjustment Procedure ..... 5-16
Abbreviations for Replaceable
Parts: Mist 2223.20 acai bane eek 6-1
Replaceable Parts...................... 6-3
List of Manufacturer Codes.......... 6-21
Manual Changes..................00005 7-1
Troubleshooting Sequence.............. 8-9
Time Base Troubleshooting ........... 8-10
Schematic Notes ..........0........00. 8-11

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Model 1740A
General Information
SECTION |
GENERAL INFORMATION
1-1. INTRODUCTION.
1-2. The Hewlett-Packard Model 1740A is a dual-
channel, 100-MHz, delayed sweep oscilloscope de-
signed for general-purpose bench or field use. The
dual-channel vertical deflection system has 12 cali-
brated deflection factors from 5 mV/div to 20 V/div.
Input impedance is selectable (50 ohms or 1 megohm)
to meet various measurement requirements. The
horizontal deflection system has calibrated sweep
rates from 2 s/div to 0.05 us/div and delayed sweep
rates from 20 ms/div to 0.05 us/div. A 10X magnifier
expands all sweeps by a factor of 10 and extends the
fastest sweep to 5 ns/div. In alternate or chop modes,
the trigger-view control feature will display three
signals: channel A, channel B, and trigger signal. This
allows correlation of the time between the trigger
signal and the channel A and channel B signals. With
the A VS B control, an X-Y mode of operation is
possible. The channel A input (Y-axis) is plotted versus
the channel B input (X-axis).
1-3. This manual contains installation and operating
instructions, as well as maintenance information for
the Model 1740A. Instrument specifications and pro-
cedures for verifying proper operation are included.
Procedures are also included for adjusting the instru-
ment to its performance specifications. Schematic
diagrams, the theory of operation, and troubleshooting
information are provided for use in maintaining the
instrument.
1-4, This section of the manual contains the perform-
ance specifications for the Model 1740A, and a list of
the options available. It also lists the accessories sup-
plied with the Model 1740A and other accessories that
are available. Instrument and manual identification in-
formation are also included.
1-5. SPECIFICATIONS.
1-6. Table 1-1 is a complete list of the Model 1740A
critical specifications that are controlled by tolerances.
Table 1-2 contains general information that describes
operating characteristics of the Model 1740A.
1-7. Any change in the specifications due to manufac-
turing, design, or traceability to the U.S. National
Bureau of Standards will be listed on a manual change
sheet included with this manual. The manual and
manual change sheet supersede all previous infor-
mation concerning specifications of the 1740A.
1-8. ACCESSORIES SUPPLIED.
1-9. The following accessories are supplied with the
1740A:
One Blue Light Filter, HP Part No. 01740-02701
One Front-panel Cover, HP Part No. 5040-0516
One Accessory Storage Pouch, HP Part No. 1540-
0292
Two 10:1 Divider Probes, HP Model No. 10006D
1-10. ACCESSORIES AVAILABLE.
1-11. The following accessories are available for the
1740A:
Model 10002A 50:1 Divider Probe
Model 10004D 10:1 Divider Probe
Model 10007B 1:1 Divider Probe
Model 10020A Resistive Divider Prove Kit (Divi-
sion ratios of 1:1, 5:1, 10:1, 20:1, 50:1, and 100:1)
Model 10173A: RFI Metal Mesh Contrast Screen
Model 10140A: Collapsible Viewing Hood
Model 197A: Oscilloscope Camera (Requires a
Model 10376A Adapter for mounting on 1740A)
Models 1001A, 1002A, and 1114A: Testmobiles
(All accept the Model 1740A and provide mobile
stands for the oscilloscope)
1-12. OPTIONS.
1-13. The options listed below extend the usefulness
of the Model 1740A.
OPTION 001. Option 001 replaces the standard de-
tachable power cord with a captive power cord. There
are two standard options available that install a special
CRT in the standard instrument. The only difference
between the optional CRT and the standard CRT is the
phosphor used in the CRT. Option 007 uses P7 phos-
phor and Option 011 uses P11 phosphor.
OPTION 090. This option omits the two Model 10006D
divider probes normally supplied as accessories. Other
probes listed under Accessories Available, which are
more suitable, may be specified.
OPTION 101. Option 101 is designed for optimum per-
formance with the HP Model 1607A Logic State An-
alyzer to provide both digital logical state and analog
electrical analysis. (Refer to Section IV for circuit de-
tails and Section VI for a list of replaceable parts in
Option 101.)
1-1

General Information
OPTION
102.
Option
102
is
Option
101
with
an
addi-
tional
special
adapter
plate
(HP
Part
No.
5061-1213).
The
special
adpater
plate
is
used
to
attach
the
1740A
and
1607A
instruments
together
as
a
single
unit.
OPTIONS 900 - 903. Options 900 through 903 are
special cord options. The connector configurations
are shown in Section II of this manual.
1-14. INSTRUMENT AND MANUAL IDEN-
TIFICATION.
1-15. Instrument identification by serial number is
located on the rear panel. Hewlett-Packard uses a
two-section serial number consisting of a four-digit
prefix and a five-digit suffix, separated by a letter
Model 1740A
designating the country in which the instrument was
manufactured. (A = U.S.A; G = West Germany; J =
Japan; U = Unit Kingdom.)
1-16. This manual applies to instruments with a serial
prefix number as shown on the title page. If changes
have been made in the instrument since this manual
was printed, a “Manual Changes” supplement supplied
with the manual will define these changes. Be sure to
record these changes in your manual. Backdating
information in Section VII adapts the manual to in-
struments with serial numbers lower than that shown
on the title page. Part numbers for the manual and the
microfiche copy of the manual are also shown on the
title page.
Table 1-1. Specifications
VERTICAL DISPLAY MODES
Channel A; channel B; channels A and B displayed
alternately on successive sweeps (ALT); channels A
and B displayed by switching between channels at
an approximate 250 kHz rate with blanking during
switching (CHOP); channel A plus channel B (alge-
braic addition); and trigger view.
VERTICAL AMPLIFIERS (2)
Bandwidth and Rise Time at all deflection factors
from 0°C to +55°C.
BANDWIDTH: 3 dB down from 6 div reference signal.
DC-Coupled: dc to 100 MHz in both 500 and 1 MQ in-
put modes.
AC-Coupled: approx 10 Hz to 100 MHz; 1 Hz with 10:1
divider probes.
BANDWIDTH LIMIT: limits upper bandwidth to approx
20 MHz.
RISE TIME: <3.5 ns, measured from 10% to 90% points
of a 6 div input step.
DEFLECTION FACTOR
Ranges: 5 mV/div to 20 V/div (12 calibrated positions)
in 1, 2, 5 sequence, accurate within 3%.
Vernier: continuously variable between all ranges,
extends maximum deflection factor to at least 50
V/div. UNCAL light indicates when vernier is not
in the CAL position.
POLARITY: channel B may be inverted, front panel
pushbutton.
DELAY LINE: input signals are delayed sufficiently to
view leading edge of input pulse without advanced
trigger.
INPUT COUPLING: selectable AC or DC, 500 (dc), or
ground. Ground position disconnects input connector
and grounds amplifier input.
INPUT RC (selectable)
AC or OC: 1 MQ +2% shunted by approx 20 pF.
50 Ohm: 500 +3%; SWR <1.4 at 100 MHz on all
ranges.
MAXIMUM INPUT
AC or DC: 250 V (dc + peak ac) or 500 V p-p at 1 kHz or
less.
50 Ohm: 5 V rms.
A+B OPERATION
Amplifier: bandwidth and deflection factors are un-
1-2
changed; channel B may be inverted for A—B oper-
ation.
Differential (A—B) Common Mode: CMRR is at least
20 dB from de to 20 MHz. Common mode signal
amplitude equivalent to 8 divisions with one vernier
adjusted for optimum rejection.
VERTICAL MAGNIFICATION (X5)
BANDWIDTH: 3 dB down from 8 div reference signal.
DC-Coupled: dc to approx 40 MHz.
AC-Coupled: approx 10 Hz to 40 MHz.
RISE TIME: <9 ns (measured from 10% to 90% points of
8 div input step).
DEFLECTION FACTOR: increases sensitivity of each
deflection factor setting by a factor of 5 with a maxi-
mum sensitivity of 1 mV on channels A and B.
TRIGGER SOURCE
Selectable from channel A, channel B, composite, or
line frequency.
CHANNEL A: all display modes triggered by channel A
signal.
CHANNEL B: all display modes triggered by channel B
signal.
COMPOSITE: all display modes triggered by displayed
signal except in Chop. In Chop mode, trigger signal is
derived from channel A.
LINE FREQUENCY: trigger signal is derived from
power line frequency.
TRIGGER VIEW
Display internal or external trigger signal in
Alternate or Chop mode, channel] A, channel B, and
the trigger signals are displayed. In channel A or
B mode, Trigger View overrides that channel. Inter-
nal trigger signal amplitude approximates vertical
signal amplitude. Ext trigger signal deflection factor
is approx 100 mV/div or 1 V/div in EXT -10.
Triggering point is approx center screen. With
identically timed signals to a vertical input and
the Ext trigger input, trigger signal delay is 2.5 ns
+l ns.
HORIZONTAL DISPLAY MODES
Main, main intensified, mixed, delayed, mag X10,
and A vs. B.
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Model
1740A
General
Information
Table
1-1.
Specifications
(Cont'd)
MAIN
AND
DELAYED
TIME
BASES
Single:
sweep
occurs
once
with
same
triggering
RANGES
as
Normal;
reset
pushbutton
arms
sweep
and
Main:
50
ns/div
to
2
s/div
(24
ranges)
in
1,
2,
5
se-
lights
indicator.
quence.
Delayed:
50
ns/div
to
20
ms/div
(18
ranges)
in
1,
2,5
DELAYED
SWEEP
(SWEEP
AFTER
DELAY)
sequence.
Auto:
delayed
sweep
automatically
starts
at
end
of
delay.
Accuracy
Trig:
delayed
sweep
is
armed
and
triggerable
at
end
of
delay
period.
Sweep
Time/Div
Temp
Range
0°C to +15°C
+15°C to +385°C
+35°C to +55°C
INTERNAL:
de
to
25
MHz
on
signals
causing
0.3
divi-
sions
or
more
vertical
deflection,
increasing
to
1
division
of
vertical
deflection
at
100
MHz
in
all
display
modes
(required
signal
level
is
increased
by
2
when
in
Chop
mode
and
by
5
when
X5
vertical
magnifier
is
used).
Triggering
on
Line
frequency
is
also
selectable.
*Add
1%
for
50
ms
to
2s
ranges.
EXTERNAL:
dc
to
50
MHz
on
signals
of
50
mV
p-p
or
more
increasing
to
100
mV
p-p
at
100
MHz
MAIN
SWEEP
VERNIER:
continuously
variable
be-
(required
signal
level
is
increased
by
tween
all
ranges,
extends
slowest
sweep
to
at
least
5
2
when
in
Chop
mode).
s/div.
UNCAL
light
indicates
when
vernier
is
not
in
CAL
position.
EXTERNAL
INPUT
RC:
approx
1
MQ
shunted
by
MAGNIFIER
(X10):
expands
all
sweeps
by
a
factor
of
approx
20
pF.
10,
extends
fastest
sweep
to
5
ns/div.
MAXIMUM
EXTERNAL
INPUT:
250
V
(dc
+
peak
ac)
or
500
V
p-p
ac at
1
kHz
or
less.
CALIBRATED
SWEEP
DELAY
LEVEL
and
SLOPE
DELAY
TIME
RANGE:
0.5
to
10
X
Main
Time/
Internal:
at
any
point
on
the
positive
or
negative
slope
Div
settings
of
100
ns
to
2
s
(minimum
delay
of
the
displayed
waveform.
150
ns).
External:
continuously
variable
from
+1.5
V
to
—15V
on
either
slope
of
the
trigger
signal,
+15
V
to—15
V
in
divide
by
10
mode
(+10).
COUPLING:
AC,
DC,
Main
LF
REJ,
or
Main
HF
REJ.
AC:
attenuates
signals
below
approx
20
Hz.
LF
Reject
(Main
Sweep):
attenuates
signals
below
approx
4
kHz.
HF
Reject
(Main
Sweep):
attenuates
signals
above
approx
4
kHz.
TRIGGER
HOLDOFF
(Main
Sweep):
increases
sweep
holdoff
time
in
all
ranges.
DIFFERENTIAL
TIME
MEASUREMENT
ACCURACY
*Accuracy
(+15°C to +35°C)
Main
Time
Base
Setting
100
ns/div
to
20
ms/div
|
+(0.5%
+
0.1%
of
full
scale)
50
ms/div
to
2
s/div
+(1%
+
0.1%
of
full
scale)
*Add
1%
for
temperatures
from
0°C
to
+15°C
and
CALIBRATED
MIXED
TIME
BASE
+35°C
to
+55°C.,
Dual
time
base
in
which
the
main
time
base
drives
the
first
portion
of
sweep
and
the
delayed
time
base
completes
the
sweep
at
the
faster
delayed
sweep.
DELAY
JITTER:
<0.002%
(1
part
in
50
000)
of
maxi-
Also
operates
in
single
sweep
mode.
Accuracy,
add
mum
delay
in
each
step
from
+15°C
to
+35°C;
2%
to
main
time
base
accuracy.
<0.005%
(1
part
in
20
000)
from
0°C
to
+15°C
and
+35°C to +55°C.
A
vs.
B
OPERATION
TRIGGERING
BANDWIDTH
MAIN
SWEEP
Channel
A
(Y-axis):
same
as
channel
A.
Normal:
Sweep
is
triggered
by
internal
or
external
Channel
B
(X-axis):
dc
to
5
MHz.
signal.
DEFLECTION
FACTOR:
5
mV/div
to
90
V/div
(12
Automatic:
bright
baseline
displayed
in
absence
calibrated
positions)
in
1,
2,
5
sequence.
of
input
signal.
Triggering
is
same
as
Normal
PHASE
DIFFERENCE
BETWEEN
CHANNELS:
<3°,
above
40
Hz.
dc
to
100
kHz.
1-3

General Information
Model 1740A
Table 1-2. General Information
CATHODE-RAY TUBE AND CONTROLS
TYPE: Hewlett-Packard, 12.7 cm (5 in.) rectangular
CRT, post accelerator, approx 15 kV accelerating
potential, aluminized P31 phosphor.
GRATICULE: 8 X 10 div (1 div = 1 cm) internal, non-
parallax graticule with 0.2 subdivision markings
on major horizontal and vertical axes and markings
for rise time measurements. Internal floodgun
graticule illumination.
BEAM FINDER: returns trace to CRT screen regard-
less of setting of horizontal, vertical, or intensity
controls.
Z-AXIS INPUT (INTENSITY MODULATION): +4 V,
250 ns width pulse blanks trace of any intensity,
usable to <10 MHz for normal intensity. Input R,
1 kQ +10%. Maximum input +20 V (dc + peak ac).
REAR PANEL CONTROLS: astigmatism and trace
align.
NOTES:
1, DIMENSIONS ARE FOR GENERAL
INFORMATION ONLY. IF DIMENSIONS
ARE REQUIRED FOR BUILDING
SPECIAL INCLOSURES, CONTACT
YOUR HP FIELD ENGINEER.
. DIMENSIONS ARE IN MILLIMETERS AND
(INCHES).
597 (23 1/2)
—————— 535 (21 1/16) ———»}
-497 (19 9/16} ———————_—_—____>
GENERAL
REAR PANEL OUTPUTS: main and delayed gates, 0 V
to >+2.5 V capable of supplying approx 5 mA.
AMPLITUDE CALIBRATOR (0°C to +55°C)
1 V p-p into 21 MQ
t
+]!
Outpurveltage 0.1 V p-p into 500
ee
POWER: 100, 120, 220, 240 Vac, +10%; 48 to 440 Hz;
100 VA max.
WEIGHT: net, 13 kg (28.6 lb); shipping, 15.7 kg (34.6 |b).
OPERATING ENVIRONMENT
Temperature: 0°C to +55°C.
Humidity: to 95% relative humidity at +40°C.
Altitude: to 4600 m (15 000 ft).
Vibration: vibrated in three planes for 15 min. each
with 0.254 mm (0.010 in.) excursion, 10 to 55 Hz.
DIMENSIONS: see outline drawing.
462
(18 3/16)
=
35
(1
3/8)
|!
t+
ss
AA
ee
—
284
(11
3/16)
(7
3/4)
~ 184
cre
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Model 1740A
Installation
SECTION II
INSTALLATION
2-1. INTRODUCTION.
2-2. This section contains information and instruc-
tions necessary for installing and interfacing the
Model 1740A Oscilloscope. Included are initial inspec-
tion procedures, power and grounding requirements,
installation instructions, and procedures for re-
packaging the instrument for shipment.
2-3. INITIAL INSPECTION.
2-4, This instrument was carefully inspected both
mechanically and electrically before shipment. It
should be free of mars or scratches and in perfect elec-
trical order upon receipt. To confirm this, the instru-
ment should be inspected for physical damage in-
curred in transit. If the instrument was damaged in
transit, file a claim with the carrier. Check for supplied
accessories (listed in Section I) and test the electrical
performance of the instrument using the performance
test procedures outlined in Section V. If there is dam-
age or deficiency, see the warranty in the front of this
manual.
Read the Safety Summary at the front
of the manual before installing or
operating the instrument.
2-5. POWER CORDS AND RECEPTACLES.
2-6. Figure 2-1 illustrates the standard configuration
used for HP power cords. The HP part number directly
above each drawing is the part number for an instru-
ment power cord equipped with a connector of that
configuration. If the appropriate power cord is not
included with the instrument, notify the nearest HP —
Sales and Service Office and a replacement cord
will be provided.
STD-002-07-76
HP POWER CABLE PART NUMBERS
8120-1692 8120-0696 8120-1703 8120-1521
Option 902) Option 901 | Option 900 | Option 903
INPUT POWER RECEPTACLE TYPES
Figure 2-1. Types of Power Source Receptacles and
Applicable Input Power Cable Part Numbers
2-7. POWER REQUIREMENTS.
2-8. The 1740A can be operated from any power
source supplying 100 V, 120 V, 220 V, or 240 V
(+10%), single phase, 48 to 440 Hz. Power dissipation
is 100 VA maximum.
CAUTION
Instrument damage may result if line-
voltage selection switch is not correctly
set for the input power source.
2-9. The instrument is normally set at the factory for
120-volt operation. To operate the instrument from any
other ac power source, proceed as follows:
a. Verify that Model 1740A power cable is not
connected to any input power source.
b. Stand instrument on rear legs. Use a blade-
type screwdriver to position line-voltage selection
switch through opening in bottom cover. (Figure 2-2
shows switches set for 120-V operation.)
c. For 220-V or 240-V inputs, replace fuse F1 with
0.5 A slow-blow fuse supplied with instrument.
d. Connect input power cable to power source.
1740A-200-07-76
Figure 2-2. Line Voltage Selection Switch Settings
2-10. REPACKING FOR SHIPMENT.
2-11. If the instrument is to be shipped to a Hewlett-
Packard Sales/Service Office for service or repair,
attach a tag showing owner (with address), complete
instrument serial number, and a description of the
service required.
2-12. Use the original shipping carton and packing
material. If the original packing material is not
available, the Hewlett-Packard Sales/Service Office
will provide information and recommendations on
materials to be used.
2-1

Operation
@ LINE. S:
and off.
@ LINE IN
the instr
© BEAM FI
creases t
display v
© BEAM IN
of the CF
@ Focus. |
sharpest
focused t
ternally.
@ SCALE IL
illuminat
backgrou
@ ALT. Cha
alternate
8) Channel |
signal.
3 ] Channel |
signal.
© & © A:B. Pres
nel B@
channel J
the chan
CH B IN
results.
1740A-037
@ cHop. c
played si
ween cha
@ TRIG VIE
or extern,
tivity of
1 V/div
@ LEVEL ¢
Center sc
@ hold level
If ALT é
signals a
ected trig
channel
ESPON LOCATED
ON ROTTOR COVER
= 12) MAG X5.
tion five
mum sen
width is ¢
1740A-038-07-76
Figure 3-1.
Controls and Connectors
3-0

LINE. Switch turns instrument power on
and off.
LINE INDICATOR. Indicator lights when
the instrument power is on.
BEAM FIND. Pressing this pushbutton in-
creases the intensity and compresses the
display within the viewing area.
© BEAM INTENSITY. Controls the brightness
of the CRT display.
6 FOCUS. Adjusts the writing beam for the
o 6 6 @
sharpest trace. Always keep this display
focused to prevent damaging the CRT in-
ternally. :
SCALE ILLUM. Adjust the CRT background
illumination for good contrast between the
background and the graticule.
ALT. Channel A and B signals are displayed
alternately on consecutive sweeps.
Channel A. Displays the channel A input
signal.
Channel B. Displays the channel B input
signal.
A+B. Pressing both channel A @ and chan-
nel B @ displays the algebraic sum of the
channel A and channel B input signals. If
the channel B display is inverted (press
CH B INVT @), an A minus B display
results.
CHOP. Channel A and B signals are dis-
played simultaneously by switching bet-
ween channels at a 250-kHz rate.
TRIG VIEW. Displays the selected internal
or external trigger signal at a fixed sensi-
tivity of approximately 100 mV/div or
1 V/div with EXT = 10@. TRIGGER
LEVEL @ positions the display vertically.
Center screen indicates the trigger thres-
hold level with respect to the trigger signal.
If ALT @ or CHOP @ is selected, three
signals are displayed: channel A, the sel-
ected trigger signal (at center screen), and
channel B.
MAG X5. Magnifies the vertical presenta-
tion five times, and increases the maxi-
mum sensitivity to 1 mV/div. The band-
width is decreased to 40 MHz.
© «oO
BW LIMIT. Reduces the bandwidth of
channel A and channel B to approximately
20 MHz.
CH B INVT. Inverts the polarity of the
channel B signal. In A+B O« 3} mode,
pressing CH B INVT @ results in an A
minus B display.
TRIGGER A. Selects a sample of the chan-
nel A signal as the trigger signal when
INT/EXT @ is in INT.
TRIGGER B. When in INT, a sample of the
channel B signal is selected as the trig-
ger signal.
COMP. When the display mode is set to
channel A, channel B, ALT, or A+B, the
sweep is triggered by the displayed signal.
When in CHOP, the sweep is triggered by
the channel A signal only.
AC. Selects the input coupling and imped-
ance for the vertical amplifiers. In the AC
position the de component of the input
signal is blocked. The lower 3-dB limit
is approximately 10 Hz.
GND. The input signa: is disconnected
from the amplifier, and the amplifier input
is grounded.
DC. All elements of the input signal are
passed to the vertical amplifier. The input
impedance is approximately 1 megohm
shunted by 20 pF.
500. The input signal is dc coupled, and the
input
impedance
is
500.
Pull
the
lever
forward
and
down
to
select
this
position.
Do
not
apply
more
than
5
V
rms
to
the
input connector.
VOLTS/DIV. Selects the vertical deflection
factor in a 1, 2, 5 sequence from 0.005 V/
div to 20 V/div, accurate within 3% with
vernier @ in the CAL position.
Vernier. Provides continuous control of the
deflection factor between calibrated
VOLTS/DIV ranges. Vernier range is at
least 2.5 to 1.
UNCAL. Lights when the vernier control
is out of detent position to indicate
VOLTS/DIV is uncalibrated.
25 a 25)
CO!
gr
car
nal
GE
Re:
CIN
of
trig
the
dis
sele

2
INFUT. BNC connector to apply external
signals to the channel A (Y) and channel
B (X) amplifier. Impedance and coupling
are selectable by@. Do not apply more
than 250 V (dc + peak ac) or more than
500 V p-p ac at 1 kHz or less.
POSN. Controls the vertical position of the
display.
CAL 1 V. Provides a 1-V_ peak-to-peak
(within 1%) square-wave voltage signal
recurring at an approximate rate of 1.4
kHz (100 mV _ peak-to-peak when termi-
nated in 50Q).
GROUND POST. Convenient chassis ground
connector. Useful to ensure a common
ground with equipment under test.
POSITION. Coarse @ and FINE @ad-
justments position the display horizontal-
ly.
AUTO/NORM. AUTO sweep mode (push-
button out). A free running sweep provides
a bright display in the absence of a trigger
signal.
NORM sweep mode (pushbutton in)
requires an internal or external signal to
generate a sweep and must be used if the
input frequency is less than 40 Hz.
SINGLE. Sweep occurs once with the same
triggering as in NORM. After each sweep,
the trigger circuit must be manually RE-
SET@.
RESET. Momentary pushbutton that arms
the trigger circuit in the single-sweep
mode. After pressing RESET@, the sweep
can be triggered by an internal or exter-
nal trigger signal or by rotating the TRIG-
GER LEVEL control @ through zero.
Reset Lamp. When lit, indicates the trigger
circuit is armed. Lamp goes off at the end
of the sweep and remains off until the
trigger circuit is again armed by pressing
the reset button.
MAIN. Selects main sweep for horizontal
display. Sweep rate and triggering are
selected by the main-sweep controls @ -
®.and © -O©.
@
A VS B. Selects an X-Y mode of operation
with channel A input (Y-axis) plotted
versus channel B input (X-axis). Vertical
positioning is adjusted by channel A
POSN@), and horizontal positioning is
adjusted by POSITION @ and FINE@.
OPTION 101. Deletes the A VS B function
and adds logic state display. When the
Model 1740A is connected to a HP Model
1607A Logic State Analyzer, pressing
STATE DSPL @displays a 16-word
table of 16-bit words.
MAG X10. Magnifies the horizontal display
10 times, and expands the fastest sweep
time to 5 ns/div, maintaining a sweep
accuracy within 3% at room temperature.
MAIN TIME/DIV. The inner knob controls
the main-sweep rate, which is indicated by
the numbers displayed in the knob skirt
opening. Sweep accuracy is within 2% (un-
magnified) at room temperatures.
DLY'D TIME/DIV. The outer rotating
section selects the delayed-sweep rate,
which is indicated by the marker on the
outer knob. Sweep accuracy is the same as
with MAIN TIME/DIV. An interlock is
incorporated so the delayed sweep is al-
ways faster than the main sweep. When
rotated out of the off position in the MAIN
mode@, a portion of the main sweep is
intensified indicating the length and delay
position of the delayed sweep with respect
to the main sweep.
SWEEP VERNIER. Provides continuous ad-
justment of main sweep TIME/DIV bet-
ween calibrated positions, extending the
slowest sweep to 5 s/div.
UNCAL. Lights when SWEEP VERNIER
@ is out of the CAL detent position, and
indicates that the sweep is not calibrated.
TRIGGER HOLDOFF. Increases the time
between sweeps and aids triggering on
complex displays such as digital words.
TRIGGER LEVEL. Selects the voltage level
on the input trigger signal where the sweep
is triggered. With external trigger signals,
the trigger level is continuously variable
from +1.5 V to —1.5 V on either slope of
the input trigger signal; +15 V to —15 V in
EXT = 10 a5} mode. With internal trigger
signals, the trigger level selects any point
on the vertical waveform displayed.
O«@
oO
0«@
O«@
O«®@
Ms BE ss)
POS/NE
that sel
INT@)
sweep.
LF REJ
trigger s
This is
signals
nating
such as
HF REJ
trigger s
This is
signals
nating
such as
LINE. §
REJ @
INT @®
circuit ¢
signal f
AC/DC.
below a
INT/EX’
nal vert
source {
signal |
put for
circuit.
EXT = °
or @ ir
EXT TR
trigger
mately
mately
250 V |
1 kHz o
DELAY.
variable
MAIN’
DLY'D.
tal disp

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POS/NEG.
Two-position
pushbutton
switch
Mt)
0<o
O«@
O«@
O«@
that selects the slope of the (EXT @ or
INT@) trigger siganl used to start the
sweep. :
LF REJ. Attenuates internal or external
trigger signals below approximately 4 kHz.
This is useful to condition high-frequency
signals for best synchronization by elimi-
nating unwanted high-frequency signals
such as power line interference.
HF REJ. Attenuates internal or external
trigger signals above approximately 4 kHz.
This is useful to condition low-frequency
signals for best synchronization by elimi-
nating unwanted high-frequency signals
such as RF.
LINE. Selecting both LF REJ @ and HF
REJ Q removes” all EXT (44) input or
INT © displayed signals from the trigger
circuit and applies a power-line frequency
signal for triggering.
AC/DC.
Selects
ac
or
de
coupling
of
the
input
(EXT
@
or
@)
or
displayed
(INT
44)
or
@)
signal
to
the
trigger
circuit.
The
DC
position
must
be
selected
for
signals
below
approximately
20
Hz.
INT/EXT. INT selects a sample of the inter-
nal vertical signal chosen by the TRIGGER
source @ or@, while EXT selects the
signal at the EXT TRIGGER @ or @ in-
put for application to the main trigger
circuit.
EXT = 10. Attenuates EXT TRIGGER @
or 56) input signal by a factor of 10.
EXT TRIGGER. BNC connector for external
trigger input. Input impedance is approxi-
mately one megohm shunted by approxi-
mately 20 pF. Do not apply more than
250 V (de + peak ac) or 500 V p-p ac at
1 kHz or less.
DELAY. The DELAY control provides a
variable delay time from 0.5 to 10X the
MAIN
TIME/DIV
settings
of
100
ns
to
2s.
DLY'D. Selects delayed sweep for horizon-
tal display.
oO
e 6
© 8©0C 66
Model 1740A
MIXED. Selects main and delayed sweeps
for the horizontal display. The first portion
of the sweep is at the main sweep rate,
and the second portion of the sweep
(starting point chosen by DELAY @) is
at the delayed-sweep rate.
SWEEP AFTER DELAY AUTO/TRIG. Selects
the method of starting the delayed-sweep
when in main intensified, delayed, or
mixed mode operation. In AUTO, delayed
sweep starts immediately after the delay
interval, which is the product of the DE-
LAY @dial reading (div) and the main
TIME/DIV @ reading. In TRIG, the de-
layed-trigger circuit is armed after the
delay interval and delayed sweep must be
triggered by either an internal or external
trigger signal.
Z-AXIS INPUT. BNC connector for inten-
sity modulation of the CRT display. A
+4-volt, 250-ns width pulse blanks a trace
of any intensity. Do not apply more than
+20 V (de + peak ac).
TRACE ALIGN. Screwdriver adjustment to
align the horizontal trace with the grati-
cule.
ASTIGMATISM. Screwdriver adjustment
used in conjunction with FOCUS @ to
achieve a clean, sharp spot or trace. Ad-
justinent is easier with a stationary spot.
LINE INPUT. Connector for the power cord.
MAIN GATE OUTPUT. Provides a rectan-
gular output of approximately +2.5 V
coincident with the main gate.
DLY’D GATE OUTPUT. Provides a rectan-
gular output of approximately +2.5 V
comcident with the delayed gate.
1607A INPUTS. Option 101 only.
HORIZ. X-axis
1607A.
input from HP Model
VERT. Y-axis input from HP Model 1607A.
Z-AXIS. Intensity input from HP Model
1607A.
FUSE. | A 250 V SLO-BLO for 100-V or
120-V operation. 0.5 A 250 V SLO-BLO for
220-V or 240-V operation.
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Model 1740A
Operation
SECTION Ill
OPERATION
3-1. INTRODUCTION.
3-2. This section provides general operating instruc-
tions for Model 1740A. Front- and rear-panel controls
and connectors are identified and described in figure
3-1. An initial turn-on procedure, operators calibration,
trigger selection table, and procedures for obtaining
basic displays are also included. The index numbers
after control and connector names in the text are keyed
to figure 3-1.
3-3. TURN-ON PROCEDURE.
Before turning on the oscilloscope, read
the safety summary located at the front
of this manual.
3-4. To turn on the Model 1740A, perform the fol-
lowing steps:
a. Turn all control knobs to the 12 o'clock posi-
tion except verniers @ and SWEEP VERNIER
should be in CAL position; TRIGGER HOLDOFF
on MIN. MAIN TIME/DIV @ fully clockwise.
b. Verify pushbuttons out except A@, AQ,
and MAIN @
c. Press LINE switch @; LINE indicator @
should light. After CRT warm up, a free-running trace
should be observed near center screen.
d. Increase (or decrease) BEAM INTENSITY @
to comfortable viewing level, and adjust FOCUS 5 | as
necessary for sharpest trace.
3-5. OPERATOR CHECKS.
3-6. A few checks and adjustments may be required
to verify that the Model 1740A is operating properly.
If the oscilloscope is moved from one electromagnetic
environment to another, the trace alignment control
may need adjustment to align the horizontal trace with
the graticule. Astigmatism and focus controls may
need adjustment to obtain the sharpest display. Probe
compensation may be required, since total input
resistance and capacitance can vary slightly from one
oscilloscope to another.
3-7. Adjust trace alignment as follows:
a. Obtain a display as described in the turn-on
procedure.
b. With vertical POSN control @, align trace
with center graticule line.
c. With a screwdriver, adjust TRACE ALIGN @
(on rear panel) for best trace alignment with graticule
line.
3-8. Adjust astigmatism and focus as follows:
a. Select A VS B @ and lower BEAM INTEN-
SITY @ to a low level.
b. Position spot near center of CRT with POSN
@ and POSITION @ controls.
c. Adjust FOCUS 5 ] and ASTIGMATISM ©
(on rear panel) for the smallest round spot.
3-9. Perform probe compensation adjustment as
follows:
a. Connect probe to be compensated to appro-
priate vertical INPUT connector 21) and the CAL 1 V
output @.
b. Set VOLTS/DIV @ to 0.1, MAIN TIME/DIV
© to 0.2 mSEC, and input coupling @ to DC.
c. Adjust main TRIGGER LEVEL @ fora stable
display of the calibrator square-wave voltage. Display
should have flat tops. Any distortion in presentation
is caused by incorrect probe compensation.
d. If overshoot or undershoot is present, turn
screwdriver adjustment in probe for a flat-top pre-
sentation (see figure 3-2).
3-10. Perform vertical accuracy check as follows:
a. Set controls to positions indicated in turn-on
procedure.
b. Apply CAL1V ® signal to channel AINPUT
connector using a BNC to banana plug adapter
and a test lead with alligator clips.
c. Adjust channel A VOLTS/DIV @ to 0.2 V/div
and MAIN TIME/DIV @ to 0.2 mSEC/div. Square-
3-1

Operation
OVERSHOOT
CORRECT
UNDERSHOOT
1740A-003
Figure 3-2. Probe Compensation
wave amplitude should be five major divisions within
4%. For complete calibration check, refer to Section V.
3-11. Perform timing accuracy check as follows:
a. Apply an accurate calibration signal (such as
from HP Model 226A Time-mark Generator) to the
channel A INPUT @ connector.
b. Set controls to the positions indicated in the
turn-on procedure except for MAIN TIME/DIV which
should be adjusted to 0.5 uSEC/div.
c. Set marker on graticule line at far left with
horizontal position control. Markers should line up ap-
Model 1740A
proximately with each graticule line across the CRT.
The marker on the far right-hand side should be with-
in 2 mm of the graticule line.
3-12. TRIGGER SELECTION TABLE.
Table 3-1 will aid in determining the best trigger
mode for various signal conditions.
3-13. OBTAINING BASIC DISPLAYS.
3-14. These procedures will aid the operator in
becoming familiar with the operation of the Model
1740A so commonly used displays can be obtained.
Before performing the procedures, complete the turn-
on procedure and adjust the following controls:
Channel A TRIGGER................ A
Channel A coupling................ DC
Channel A VOLTS/DIV @ .......... 0.05
MAIN TIME/DIV @ .......... 0.5 mSEC
DELAY @ .................0645 fully CCW
3-15. NORMAL SWEEP DISPLAY.
a. Connect a Model 10006D probe to channel A
INPUT C21) connector, CAL 1 V ® output, and ground
post @.
Table 3-1. Display and Trigger Selection Table
SIGNAL CONDITIONS
I. Single Signals
Applied to
Channel A or B
A or B
II. Time Related Signals ALT
Applied to
Channels A & B CHOP
A+B (A—B)
III. Nontime Related Signals
Applied to
Channels A& B
Assume time related signal applied.
ALT
7 Time relation displayed.
No time relation displayed.
' If COMP is selected in CHOP, switching
overrides and selects A.
Signal is only displayed on one channel.
3-2
ALT or CHOP®
COMP EXT
OK OK!
NG OK!
NG! OK?
OK OK
NG NG
Triggers on algebraic sum or difference of
signals.
OK Useable trigger mode.
Good trigger mode.
Best trigger mode.
NG _ Unuseable trigger mode.
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Model 1740A
b.
Adjust
POSN
@
to
align
base
of
square
wave
on
the
center
graticule
line,
and
adjust
TRIGGER
LEVEL
@
for
a
stable
display.
A
square
wave
with
an
amplitude
of
two
divisions
and
approximately
five
to
nine
positive-going
pulses
will
be
displayed.
3-16.
MAGNIFIED
SWEEP
DISPLAY.
a.
Perform
paragraph
3-15
to
obtain
Normal
Sweep
Display.
b.
Adjust
horizontal
POSITION
@
to
place
waveform
portion
to
be
magnified
on
CRT
center
graticule
(see
figure
3-3).
1740A-004
Figure 3-3. Normal Display
c.
Press
MAG
X10
@and
adjust
horizontal
FINE
©
for
precise
placement
of
magnified
display
(see
figure
3-4).
3-17. DELAYED SWEEP DISPLAY.
a.
Perform
paragraph
3-15
to
obtain
Normal
Sweep
Display.
b.
Adjust
delayed
TIME/DIV
@
for
50
HSEC/
div,
and
observe
intensified
portion
of
square
wave.
Set
BEAM
INTENSITY
@
control
to
a
comfortable
viewing level.
c.
Set
SWEEP
AFTER
DELAY
to
AUTO
and
turn
DELAY
@
clockwise
until
intensified
portion
of
1740A-005
Figure 3-4. Magnified Display
Operation
trace
is
over
trace
area
to
be
investigated.
This
is
demonstrated
in
figure
3-5.
1740A-006
——
INTENSIFIED
Figure
3-5.
Normal
Display
with
Intensified
Area
d.
Press
DLY’D
©
and
note
that
intensified
portion
of
trace
is
now
displayed
across
entire
CRT
(see
figure
3-6).
e.
DELAY
@
control
may
be
adjusted
to
view
other
pulses
in
the
pulse
train.
1740A-007
Figure
3-6.
Delayed
Sweep
Display
3-18.
MIXED
SWEEP
DISPLAY.
a.
Perform
paragraph
3-15
to
obtain
Normal
Sweep
Display.
b.
Adjust
delayed
TIME/DIV
@
for
50
nSEC
and
note
intensified
portion
of
square
wave.
Set
BEAM
INTENSITY
@
to
comfortable
viewing
level.
c.
Turn
DELAY
@
clockwise
until
part
of
wave
form
in
second
half
of
CRT
is
intensified
(see
figure
3-7).
d.
Press
MIXED
@
and
observe
that
first
portion
of
the
display
is
at
main
TIME/DIV
34]
sweep
rate
and
second
portion
is
at
delayed
TIME/DIV
5]
sweep
rate
(see
figure
3-8).
The
transition
point
from
main
sweep
to
delayed
sweep
can
be
varied
by
adjusting
DELAY
control@.
3-3

Operation
1740A-008
INTENSIFIED
Figure 3-7. Normal Display with Intensified Area
3-19. X-Y DISPLAY.
a. Press A VS B@. BEAM INTENSITY @ may
need to be decreased. Apply vertical (Y-axis) signal
to channel A INPUT @ connector and horizontal
(X-axis) signal to channel B INPUT connector. Chan-
nel A POSN @ adjusts vertical positioning; POSI-
TION © adjust horizontal positioning. Adjust channel
A and B VOLTS/DIV @ controls as required.
b. If display is not visible, press BEAM FIND C3)
and adjust channel A and B VOLT/DIV controls
until display is compressed vertically. Center com-
pressed display with POSN @ and POSITION ©
1740A-009
Figure 3-8. Mixed Sweep Display
3-4
Model 1740A
controls. Release BEAM FIND, and adjust FOCUS
5) for a sharp display.
3-20. SINGLE SWEEP OPERATION.
3-21. Single sweep mode is often used to photograph
single occurrence events. To use this mode, proceed
as follows:
a. Select SINGLE © sweep mode.
b. Set AUTO/NORM to NORM@.
c. Set all trigger processing controls to desired
settings; for example, INT/EXT@, slope@, and
TRIGGER LEVEL ©.
d. Depress RESET © pushbutton; the red RE-
SET 30) lamp will light.
3-22. The sweep circuitry is now armed; as soon as
a trigger signal is received that meets the preset
requirements (slope, coupling, level, etc.), the time
base will generate one sweep. As soon as the sweep
ends, the RESET @ lamp will extinguish and the
time base must be reset again.
3-23. SINGLE SWEEP USING TRIGGER
VIEW.
3-24. To use the trigger view feature in single sweep,
perform the following steps:
a. Press TRIG VIEW @. This turns off both ver-
tical channels; however, trigger view circuitry will not
be activated until a certain transition occurs at the
end of the sweep.
b. To activate trigger view, press RESET ® and
rotate TRIGGER LEVEL @ from one extreme to the
other or engage AUTO @ and press RESET, then dis-
engage AUTO.
3-25. After one sweep has been manually generated,
the necessary transition will have occurred and trigger
view mode will operate in a normal manner.
‘
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17
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