B+K precision 1474 User manual

¼!
IMAXT
INTERNATIONAL CORP.
SERVICE MANUAL
for
Model
1474,
1479, 1479A,
and 1479B
30
MHz
Triggered Sweep
DUAL
-TRACE
OSCILLOSCOPE
IMAXTEC INTERNATIONAL CORP.

TEST
INSTRUMENT
SAFETY
WARNING
Normal use
of
test equipment and
servicing
of test equipment exposes you to a certain
amount
of
danger
from electrical
shock
because testing
must often be performed
where
exposed
high
voltage is
present. An electrical shock causing 10 milliamps
of current
to
pass
through the
heart
will stop most
human heartbeats. Voltage as low as 35 volts do or ac rms should
be
considered
dangerous an d
hazardous since it can produce a lethal
current
under certain conditions. Higher
voltage
poses
an
even
greater
threat because
such voltage
can
more easily
produce
a lethal
current. Your
normal work habits
should include
all accepted practices that
will
prevent
contact
with
exposed
high voltage,
an
d that
will
steer current away from your heart
in
case of
accidental
contact with a
high voltage. You will
significantly
reduce the
risk factor if you know an d observe
the following safety precautions:
1. High voltage
up
to
6000
volts is present when
servicing this
oscilloscope. Observe
all high
voltage
precautions when the
unit
is
operating
with
the case removed. Remember
that
a
high
voltage
charge
may
be retained indefinitely, especially at
the CRT
socket
and anode
cap. Discharge
high voltage capacitors
with a
grounded
test lead
after removing power.
2.
Don't
expose
high
voltage needlessly.
Remove housings an d covers
only
when necessary.
Turn
off
equipment
while
making
test connections in
high
-voltage circuits.
Discharge high -
voltage capacitors
after removing power.
3.
If
possible, familiarize
yourself with the equipment
being tested and
the
location of its high
voltage points.
However, remember that high voltage
may appear
at
unexpected
points in
defective
equipment.
4. Use an
insulated floor material or a large,
insulated floor
mat
to stand on, and an insulated
work
surface
on which to place
equipment;
and make
certain such surfaces
are not
damp or
wet.
5.
Use the
time -proven
"one
hand in the
pocket"
technique while handling an instrument probe.
Be particularly careful
to
avoid contacting
a
nearby
metal object
that
could
provide
a
good
ground return path.
6.
When using
the
oscilloscope,
the ground
wire
of
the 3 -wire ac power
plug places
the
chassis
an d
housing
of the oscilloscope at
earth ground.
Do not
attempt
to
defeat the
ground
wire
connection or fl oat
the oscilloscope;
to
do so may pose
a
great
safety
hazard.
7.
When using a probe, touch only
the insulated portion. Never touch
the
exposed
tip
portion.
8. When testing
ac powered
equipment, remember
that
ac line voltage
is usually present on
some
power input
circuits
such
as the on -off switch, fuses, power transformer,
etc. any
time the equipment is connected to an ac outlet, even
if
the
equipment is turned off.
continued on inside
back cover

SERVICE
MANUAL
for
B
&
K
-PRECISION
Models
1474,
1479,
1479A, and
1479B
DUAL
-TRACE
OSCILLOSCOPE
WARNING I
This service manual is intended
for
use
by
qualified
electronics
technicians only.
To
avoid
electric shock,
do
not
perform servicing unless you
are
qualified to do so.
High voltages up to 6000 V do are presentwhen this instrument
is
operating. Line
voltage (120 or 240 Vac) is present on
the
power input circuit whenever the ac power
cord in
connected to a live
outlet,
even if
the scope is turned
off.
Observe
all high
voltage
safety
precautions
when
the
housing
is
removed
from the oscilloscope.
Con-
tacting
exposed
high
voltage could
result
in fatal
electric shock.
IF_~ n
~AIL+/A&:
B &
K -Precision, Factory
Service Operations
Maxtec International Corporation
6470 West Cortland Street
Chicago, Illinois 60635
Tel [phone]
Use this address for technical inquiries and
replacement
parts orders.

TABLE
OF CONTENTS
Page
TEST INSTRUMENT SAFETY
Inside Cover
DIFFERENCES BETWEEN MODELS
1
SPECIFICATIONS
3
ACCESSORIES 8
Accessories
Supplied
8
Optional Accessories
8
Model LC
-74
Protective Cover
8
Model
LC -133 Carrying Case
8
Model RM-14
Rack
Mounting Kit
8
PR -40 10:1/Direct Probe
9
PR
-37 Deluxe 10:1/Direct Probe
12
CONTROLS
&
INDICATORS
15
General
Controls
15
Triggering Controls
16
Channel B Controls
17
Channel
A
Controls
18
Additional Facilities
18
CIRCUIT DESCRIPTION
20
Overview
20
Vertical
Attenuator and
Preamplifier
22
Vertical Mode
Logic
24
Vertical
Output Amplifier
26
Trigger Circuits
26
Horizontal
Sweep
29
Intensity Circuit
30
High Voltage Power Supply
32
Blanking
Circuit
32
Calibration
Voltage 35
Low Voltage Power Supply
35
OPERATOR MAINTENANCE
38
Astigmatism
38
DC
Balance
38
Calibration Check
38
Probe Compensation
39
Trace Rotation
39
Fuse Replacement
40
ii

TABLE OF
CONTENTS
SERVICE
41
Removing
the Case
41
Fuse
Replacement
41
120/240
V
Conversion 42
Disassembly
42
Troubleshooting 42
CALIBRATION
48
General
48
Calibration
Check
48
Test
Equipment
Required
48
Preliminary Procedure
48
Power Supply
Adjustments
49
Intensity and
Display Adjustments 49
Vertical Axis Adjustments
50
Horizontal
Axis
Adjustments
55
Triggering Adjustments
57
CAL Square
Wave
Adjustments
58
Performance
Tests
59
PARTS
LIST 63
Mechanical
Parts
List
64
Packing
Drawing 68
Electrical Parts List 70
CIRCUIT BOARD MAPS
AND SCHEMATIC
DIAGRAMS
Vertical
Amplifier Board
94
Vertical
Output Amplifier
Board 97
Horizontal
Amplifier
and Sweep
Board
100
Power Supply Board 103
Overall
Schematic Diagram,
Model 1474
106
Overall
Schematic
Diagram,
Model
1479
107
Overall Schematic Diagram,
Model 1479A
108
Overall
Schematic
Diagram, Model 1479B
109
HISTORY OF PRODUCTION
CHANGES
111
REFERENCE
PUBLICATIONS
Model 1474 Instuction Manual
480-187-9-001
Model 1479 Instruction
Manual
480-264-9-001
Model
1479A
Instruction
Manual
480-280-9-001
Model 1479B Instruction Manual
480-302-9-001
Model 1474 Composite (Schematic Diagram
and
Parts
List)
499-181-9-001
Model
1479
Composite
(Schematic Diagram
and
Parts List)
499-161-9-001
Model 1479A Composite (Schematic
Diagram
and Parts
List)
499-173-9-001
Model
1479B Composite
(Schematic Diagram
and
Parts List)
499-202-9-001
LC -133
Carrying Case
Instruction
Sheet
481-123-9-001
RM-14 Rack Mounting
Kit
Instruction Sheet
481-088-9-001
in

DIFFERENCES
BETWEEN MODELS
SH ILABITYES
This
manual covers
the service and main-
tenance
of B &
K -Precision
Models 1474,
1479,
1479A, and 1479B Triggered Sweep 30
MHz
Oscilloscopes. All
four
models
use
the same
basic circuit
configuration
and most
of the
service information applies equally
to all
models.
The
major
features
common
to
all
four of these
oscilloscopes are listed
below.
30 MHz
Bandwidth. High frequency
input
can
be
displayed with no
distortion
and
high
resolution.
11.7 ns Rine Time.
The fast rise time allows
for display of
short duration pulses.
Dual Trace. Two waveforms can
be displayed
either
singly
or simultaneuosly.
Chop
or
alternate
method of
dual trace automatic-
ally selected
by
sweep speed control.
Built
in
Delay
Line.
For viewing leading edges
of high
frequency,
fast rise time pulses.
Triggered
Sweep.
Level
control
sets
the
point
of triggering or sets
an
amplitude
that
must
be
met to
obtain a
sweep. In
dual
-sweep
mode, either channel may be used as
a
sweep trigger.
Auto
Sweep.
Provides sweep when
no
trigger
signal
is
applied. Automatically
reverts to
triggered sweep when
a signal
is applied.
Versatile
Triggering. Choice of CH
A, CH B,
or external trigger source. Selectable
trigger coupling
offers choice of
ac, dc, or
ac with high or low
frequency rejection.
FIX Mode.
A
selectable FIX mode
sets
trig-
gering
at
middle of waveform
regardless
of
LEVEL control.
1
High Sensitivity.
5
mV/div
sensitivity
permits
the
use
of low
-capacitance,
high
-impedance
probes.
Sum and Difference Capability.
Input from
both
channels may
be algebraically
added or
subtracted for differential
voltage meas-
urem ents.
Calibration
Source. A 0.5 V,
1 kHz
square
wave is
provided
to aid
in
scope checking
and
probe
compensation.
20
Sweep Speeds.
Allows for
calibrated time
measurements
from
0.2
1s/div to 0.5
s/div.
Expanded
Scale. The
trace display
can
be
magnified five times for
greater visual
accuracy.
X -Y
Operation. Channel
B
input
can be used
as
the
horizontal
deflection
(X axis) and
Channel A
as
vertical deflection (Y axis).
Z -Axis
Input. Intensity
modulation permits
time or frequency marking
from a TTL
source.
DIFFERENCES
Unless otherwise
noted, all
information in
this
manual applies equally to Model 1474,
1479,
1479A,
and 1479B. The
schematics of
the
individual
circuit boards
and
the
accom-
panying circuit board maps are the latest
version available at
the
time
of printing, but
can
generally
be
used for
troubleshooting
and
servicing
of all
four models.
A
separate
overall
schematic
of each model
is
provided
for convenience.
B & K
-Precision continually strives to
improve its products. Changes
of a significant

DIFFERENCES
BETWEEN
MODELS
nature,
such
as
adding a
function, are identi-
fied by changing the
model designation. Thus,
the model
designations
represent
the
chrono-
logical
improvements
upon the
original design.
The
Model 1474 was the
original
30 MHz
oscilloscope
based
upon this
design. It was
followed by Model
1479,
which
had consider-
able
difference
in
mechanical
appearance, an
d
AM
DETect
triggering
was added.
When the
video
sync separator
was
added,
the model
designation
was
changed to
1479A. Most
recently, with
the
change from
a
round
to
a
rectangular CRT,
the
model
designation
became 1479B.
More
specific details of the differences
between models are given
below.
Complete
part by part differences are
itemized in the
parts list.
Model
1474
is recognized by:
a
black
front
panel, a
tan
case,
a fl at
handle, a
de-
tachable
power cord, and an
external
100/120/220/240 li
ne voltage
plug.
Triggering
selection is either
CH A, CH B, EXT
(unat-
tenuated)
or EXT
1/10 (10:1 attenuation).
Model
1479
has several changes in ap-
pearance from
its
forerunner,
Model 1474.
The
1479
has a grey and silver
front panel, a
biege
case,
and a
formed
handle. Electrical
changes were also made to
trigger and sweep
circuits.
The EXT
1/10
trigger source
selec-
tion
was replaced by AM DET to allow
for
triggering on
the modulation
envelope of an
AM signal.
Adjustments were added
on
the
sweep board
for high speed
sweep
linearity.
While the
initial
production
lots
of
1479's
still
have the
detachable
power cord and
external
li
ne voltage selector plug (like the
1474), the
later units have a fixed power cord and inter-
nal 120/240
li ne voltage plug.
Model 1479A
incorporated
a
selectable
video
sync separator circuit. The
VIDEO
selection
permits
triggering on
the sync
pulses
from
a composite video signal. Vertical sync
pulses
(frame) are
automatically
selected
for
triggering
at slower sweep
times
of
0.5 s/div
to 0.1
ms/div. Such
sweep times are
approp-
riate for viewing
vertical frames of
video.
Horizontal sync
pulses (line) are
automatically
selected for triggering at
faster
sweep
times
of
50 las/div to 0.2 }.e/div (appropriate for view-
ing horizontal
lines
of video).
The front panel
is
changed
to
allow
for the
added
VIDEO/
NORM switch.
The previous
AUTO
LEVEL/
NORM
switch
is relabeled
FIX/
NORM, but
the function remains the same.
Model 1479B incorporates a rectangular
CRT
with internal etched
graticule
(non -
illuminated)
to replace the previous
round
CRT with illuminated
graticule. The power
supply
is changed to use
a -1.5
kV
CRT
cathode
voltage
and
a voltage tripler develop-
ing +4.5 kV for
the CRT anode.
This
compares
with a
-1.9
kV
cathode potential
and
voltage
doubler (+3.8 kV) for
an ode potential in prev-
ious
models.
Electrical
trace rotation
(adjust-
able
from the front panel)
was also
added.
This
includes a rotation coil on the
neck
of the
CRT
and a
corresponding trace rotation cir-
cuit on the power
supply board.
PRODUCTION CHANGES
Our
program of
continuous evaluation an
d
product
improvement may often involve minor
changes
and refinements which are not signifi-
cant
enough
to change the model designation.
Beginning
with
Model 1479A and continuing
with
Model 1479B
(unfortunately, we have no
similar
information for Model 1474 or
1479),
we
have
compiled a list of all
such
production
changes,
along
with the serial numbers where
such
changes became effective. This informa-
tion is located at the very end
of this
manual
in the
HISTORY OF PRODUCTION
CHANGES
section.
This
information should
be
helpful
when
the unit you are servicing
does
not
exactly
match the
schematic
diagram
or
parts
list
found in
this service manual. Because
produc-
tion
changes often require several compatible
parts,
working
in conjuction with each other to
achieve the improvement, replacement parts
should usually restore the
unit to its
original
configuration.

SPECIFICATIONS
Unless otherwise
stated,
all specifications apply equally to Model 1474,
1479,
1479A,
1479B.
VERTICAL
AMPLIFIERS (CH A and
CH B)
Deflection
Factor
5 mV/div to 5
V/div, t3%,
in
10 ranges,
each with fine
adjustment.
Frequency
Response
DC:
DC
to 30 MHz (
-3
dB).
AC:
10
Hz
to 30
MHz (
-3
dB).
Risetime
11.7
nanoseconds
or
less.
Overshoot
3% or less.
Input Impedance
1
megohm,
t2%,
shunted
by 23 pF
(±3
pF).
I3ilt
Less
than
5%.
Max.
Input Voltage
300 VDC
+
AC
peak
or
600
V p -p.
Operating
Modes
Channel
A only.
Channel
B
only.
Dual trace: automatically chopped
at
all
sweep
times
of 1
ms/div and slower;
alternate trace
automatically
selected
for all
faster sweep
times.
Add:
single
-trace algebraic
sum of Channels
A and B (difference
using CH B
INVert).
Chop
Frequency
200 kHz (
±20%).
Channel Separation
Better than 70 dB @ 1 kHz.
3
Signal
Delay
Fixed, 12
ns minimum visible
delay.
CH
B
Polarity
Normal, inverted (provides CH A minus
CH
B
function).
Maximum
Undistorted Amplitude
Model 1479A and 1479B:
More than 8
div
from do to
30 MHz.
Model 1474
and
1479: More than 8 div from
do to
10
MHz.
More
than
4
div to
30 MHz.
HORIZONTAL
AMPLIFIER (Horizontal input
thru
CH B
input)
X
-Y
Operation
With
SWEEP
TIME/DW
switch in CH B
position, the
CH
A
input becomes the Y
axis
input
(vertical) and
the
CH B input
becomes
the
X
axis input
(horizontal). The
CH B
position control becomes the
hor-
izontal position
control.
Deflection Factor
5
mV/div to 5 V/div,
t3%, in
10
ranges,
each
with
fine adjustment.
Frequency Response
DC:
DC to
2 MHz (
-3
dB).
AC: 10 Hz to
2
MHz ( -3 dB).
Input Impedance
1 megohm
t2%, shunted by
22 pF
(t3
pF).
Input Protection
300
VDC
+
AC
peak or 600 p -p.

SPECIFICATIONS
SWEEP CIRCUITS
(Common to CH
A
and
CH B)
Sweep System
Triggered and
automatic.
Sweep Time
0.2
1.
/div to 0.5
s/div (
t3%), in 20 ranges,
in
1-2-5
sequence
with vernier
adjustment.
Sweep Magnification
X5
(five
times) t5%.
Extends maximum
sweep rate to 40 ns/div.
Linearity
3%
or
better,
5%
or better
with
X5 magni-
fi cation.
TRIGGERING
Source
Model 1474: CH A, CH B, EXT, and
EXT
1/10.
Model
1479,
1479A,
and
1479B: CH
A,
CH B,
EXT and AM DET.
Automatic
Sweep is triggered
without input signal.
Normal
Sweep is
obtained
with a displayed signal
amplitude of one division or
less.
The point
on
the displayedwaveform at
which
the
sweep starts is determined by the SLOPE
and
LEVEL controls.
Slope
Sweep can be set to trigger on the positive
or negative going
slope
of
the
trigger
waveform.
Level
Continuously variable. Pull for
AUTO
(Sweep is obtained without an input signal).
FIX
Automatically
fixes triggering level at
center of
trigger
signal.
AM DET
(Models
1479, 1479A
and
1479B)
Triggers
from modulation
envelope
of
amplitude
modulated signal
(carrier,
fre-
quency 3 MHz or greater).
4
Coupling
AC:
DC:
LF REJ:
HF
REJ:
• 20 Hz
to 30 MHz
DC to
30 MHz.
Attenuate
below
10
kHz.
Attenuate
above
30
kHz.
Video (Model 1479A
and
1479B only)
Vertical and horizontal sync
separator
circuit provided so
that any
portion of
composite video waveform can be
synchron-
ized
and expanded for viewing. LINE
sync
(horizontal sync pulses)
automatically
selected
at
sweep times
of
.21.5/din. to
0.515/div. and FRAME sync
(vertical sync
pulses)
automatically selected at
sweep
times of
.1
ms/din. to
.5 s/div.
TRIGGER SENSTITVPFY
Minimum Scnc Voltage
Coupling
Bandwidth
INT
EXT
AC
20Hz - 15MHz
10Hz - 30MHz
0.3 Div.
1
Div.
0.1 V pp
0.5
V pp
I F REJ
20kHz - 15MHz
l0kHz -
30MHz
0.3 Div.
1 Div.
0.1 V pp
0.5
V pp
HF REJ
20Hz - 50kHz
10Hz
-
300kHz
0.3 Div.
1
Div.
0.1 V pp
0.5
V pp
NORM
DC
FIX
DC-
15MIlz
DC-30MHz
0.3 Div.
1 Div.
0.1 V pp
0.5 V pp
20Hz - 15MHz
10Hz -
20MHz
0.3
Div.
1
Div.
0.1 V pp
0.5
V pp
Z
AXIS
INPUT
(Intensity
Modulation)
Sensitivity
5
V
(TTL compatible).
Usable Frequency
Range
DC to 5 MHz.
Input Impedance
10
kSZ.
Maximum
Input Voltage
50VDC+AC
peak.

SPECIFICATIONS
OTHER SPECIFICATIONS
Operating Environment
0 o
to
+
45O
C.
Power Requirements
117/234
VAC,
50/60
Hz,
25 watts. Calibra-
tion will
remain constant over
105
to
130
VAC input.
Calibration
Internal 0.5
V p -p
±1%
(square wave
at
1 kHz
t3%).
OVERALL DIMENSIONS
(Fig. 1)
295 x 202 x 437 cm.
Maximum (WxHzD)
(11-5/8 x 7-15/16 x 17-13/16")
Weight
8.5
kg; 19 lb.
Fig. 1.
Overall
Dimensions.
5
CRT
Models 1474,
1479,
and
1479A
5" Round CRT with
P31 phosphor.
Post
deflection acceleration.
Approx.
4
kV
acceleration.
8 x
10 division
graticule
scale
(1 division = 1 cm), variable
illumination.
Mechanical trace
rotation. See
H9155A-P31 CRT specifications
for
more
detail.
Model 1479B
140
mm
rectangular
CRT.
Internal
8
x
10
division graticule scale
(1
division =
.9
cm). Post deflection
acceleration.
Approx.
6
kV
acceleration. Electrical trace
rotation,
adjustable
from front
panel.
See
140CGB31 CRT
specifications
for
more
detail.

SPECIFICATIONS
H9155A-P31
G1
G2
PDS"
Bottom
View
P2
P1
PDC:
PDC:
Note:
Post deflection shield
Pattern
distortion
compensation
SD:
Interplate
shield
Fig.
2.
H9155A-P31 Basing Diagram.
Fig.
3.
140CGB31
Basing Diagram.
H9155A-P31 CRT
Specifications
140CGB31 CRT
Specifications
(refer to Fig.
3)
(refer
to
Fig. 2)
Dimensions Dimensions
Overall
Length
Overall
Length
310 mm or
less.
355mm.
Face
plate dimension:
Face Plate
Dimensions
133±1.8 mm.
143.5±1.5 mm
maximum.
Screen Shape
Screen
Shape
Round and Flat Face.
Rectangular, flat
face, internal graticule.
Focusing
Focusing
Electrostatic
deflection and focusing. Post
Electrostatic
deflection and
focusing.
Post
deflection acceleration.
deflection
acceleration.
Flourescence
Flourescence
Green.
Green.
Persistence Persistence
Medium
short.
Medium short.
Display
Area
Display
Area
110x90mm 2 .
95.0 x
76.0 mm2.

SPECIFICATIONS
H9155A-P31
CRT
Specifications
(continued)
Heater voltage
6.3
V f10%.
Heater current
0.095 A
±10%.
2nd Plate voltage
1400 V.
Capacitance
Gl to
all
other element:
7.5
pF.
R
to all other element:
4.0 pF.
7
140CGB31 CRT
Specifications
(continued)
Heater
Voltage
6.3V
Heater
Current
0.24 A.
3rd Plate
Voltage
6.3
V
maximum.
2nd Plate Voltage
1800
V
maximum.
2nd
Grid Voltage
1700
V
maximum.
1st
Grid
Voltage
200
V
maximum.
Cathode
to
Heater
Voltage
125 V
maximum.
Voltage
Between 2nd
Plate
and
Any
Deflection Plate
500
V
maximum.

ACCESSORIES
ACCESSORIES SUPPLIED
Two
10:1/Direct Probes.
Instruction Manual.
Composite
(Schematic
Diagram
List).
Spare
Fuse.
OPTIONAL ACCESSORIES
LC -74 Protective Cover.
LC
-133
Carrying Case.
RM-14 Rack Mounting
Kit.
PR -37 DeLuxe
10:1/Direct Probes.
MODEL LC -74 PROTECTIVE
COVER
& Parts
This
rugged grained leatherette cover
covers the
front panel and
provides light-
weight,
convenient protection while
transport-
ing the
oscilloscope. A handy
pocket
provides
stowage for
probes.
S
MODEL
LC -133 CARRYING
CASE
A
carrying case that completely
encloses
the oscilloscope, providing
superior protection
while
transporting the unit. A
probe
stowage
pocket
is
provided.
MODEL RM-14 RACK
MOUNTING KIT
This kit includes the
panel hardware and
instructions
needed
to mount
the
oscilloscope
in a standard 19 inch rack.

PR -40 10:1/DIRECT PROBE
GND
SELECTOR
SWITCH -
PROBE
COMPENSATION
ADJUSTMENT
PR
-40 10:1/Direct
Probe.
ITEM DESCRIPTION
PART
NO.
Complete PR
-40
Probe
with accessory
tips
535-040-0-000
1
Probe
&
Cable Assembly
523-324-9-001
2
Spring Hook
Assembly
523-316-9-001
3 Ground Wire Assembly 523-325-9-001
4
IC Tip
380-378-9-001
5
Insulating Tip 380-378-9-002
6
BNC
Adapter
768-016-9-001
Red
Adhesive Strip 485-018-9-001
Gray
Adhesive Strip
485-018-9-002
Instruction Sheet
481-121-9-001
9

PR -40
10:1/DIRECT
PROBE
SPECIFICATIONS
lox position
1X
position
Attenuation
10:1
±1%
(at oscilloscope input
impedance
of 1
MSZ ±1%)
-
Input Impedance
10M±1% 1
MSZ
tl%
Input Capacitance
less
than
18 pF less
than
100 pF
Bandwidth
100 MHz
15
MHz
Rise Time
3.5 ns
24
ns
Compensation
Range
15 to 40 pF
Maximum Input
Voltage
500 V p -p;
250
V
do
+
ac
peak
DESCRIPTION
The B & K
-Precision
Model PR
-40 deluxe
probe is designed for
use with
wideband oscill-
oscopes to 100
MHz.
The
PR -40 is a
slim -body
probe of precision
lightweight
construction. A
three
position switch selects 10:1 or
direct
modes, or a
reference position that
grounds
the
tip through a 9
megohm resistor.
Accessories included with the PR -40 are a
spring -loaded
retractable tip cover,
insulating
tip,
BNC tip
adapter, and
IC tip.
The insulat-
ing
tip
is
designed
for
probing
dense solid-
state
circuitry
with
little danger
of shorting
nearby components. The
BNC
adapter tip
converts the probe
tip into
a
push
-on
BNC
fitting,
ideal for interface with
test points or
output
jacks.
The
IC tip
guides the
probe
contact into any pin of a standard
DIP, making
it
almost impossible
to short two pins of an
IC.
The PR -40 is
supplied
with both
grey
and
red adhesive
strips, which
are particularly
useful with
a dual
-trace
scope for instant
identification
of the channel to which
a,probe
is connected.
The PR
-40 and accessories
come in a
convenient vinyl
case.
10
OPERATION
By
setting
the
selector
switch
of the probe
to the "1X" position, an
unattenuated
wave-
form
can
be observed. Note that
bandwidth
is
15
MHz
in
this
position.
By setting the switch to the
"10X" posi-
tion, the probe
input impedance is increased to
10
megohms and
the
waveform being observed
is attenuated 10:1. The "10X" position
must
be
used above 15 MHz an d whenever
the
load-
ing
effect of the
probe may disturb
normal
operation of a circuit. Signal
attenuation
is
10:1 when
using the standard 1 megohm input
impedance
(use
coaxial cable rather than the
probe when
terminated
into
50
ohms). This
high impedance probe will cause
very little
error
in
measurements in
circuits
of 1 megohm
impedance
or
less.
The "REF" positon of
the
probe
selector
switch
opens the probe input and grounds the
oscilloscope input, allowing convenient
measurement of reference level.

PR
-40
10:1/DIRECT
PROBE
ADJUSTMENT
Set the probe
selector switch to
the "10X"
position. Connect
probe to
vertical input of
oscilloscope. Use
the
oscilloscope's most sens-
itive
vertical
attenuator
setting and,
while
observing a 1
kHz
or
10 kHz
square wave
signal,
adjust
the
trimmer on the
probe with
an insulated screwdriver
for best
square wave
presentation; that is,
least overshoot,
tilt, and
rounding off
of square wave.
11
SERVICING
The probe
is not repairable. This includes
both
repairs
to the main
probe assembly
and
replacement of the
special
type coaxial cable.
The impedance, capacitance,
and
bandwidth
characteristics of
the probe are very
critical,
and
can
only be
assured by
assembly
at
the
factory.
Servicing consists of probe compen-
sation
adjustment
and replacement of those
items listed
in
the parts list.

PR
-37 DELUXE 10:1/DIRECT
PROBE
PR -37
Deluxe 10:1/Direct Probe.
ITEM DESCRIPTION
PART
NO.
Complete Dual
PR -37 Probe
Set
with accesory
tips,
1 Gray and 1 Red
534-096-0-000
Complete
PR -37(G)
Probe
with accessory
tips,
Gray
534-097-0-000
Complete PR
-37(R) Probe
with
accessory
tips,
Red
534-098-0-000
1
Spring Hook
Assembly, Gray
521-090-9-001
1
Spring
Hook Assembly,
Red
521-091-9-001
2 BNC
Adapter
521-089-9-004
3
Insulating
Tip
521-089-9-001
4
IC Tip
521-089-9-005
5 Trimmer
Tool
521-089-9-003
12

PR -3?
DELUXE 10:1/DIRECT PROBE
30
40 50
SPECIFICATIONS
lox
positiam
1X position
Bandwidth do to
100
MHz
do to 10
MHz
Rise Time
3.5 ns
35
ns
Input Impedance
10
MS2 ±1%
(when used
with
oscilloscopes
with
a 1
MSZ
input)
1 MS2
(oscilloscope input)
Input
Capacitance 11.5 pF
(when used with
oscilloscopes which
have
30 pF
input
capacitance) *
40 pF
(plus oscilloscope
capacitance)
Compensation
Range
10
to 60 pF
Maximum
Input
Voltage
600 volts p -p
or do
+
ac
peak
REF Positon probe
grounded via
9
MS2 resistor,
oscilloscope input grounded
Connector
BN C
Length approx.60
T1
* = for other
values see
graph.
10 15
20 60
Oscilloscope Input Capacitance
13

PR -37
DELUXE
10:1/DIRECT PROBE
DESCRIPTION
The B&K-PRECISION Model PR -37 deluxe
probe is
designed for use with wideband oscill-
oscopes to
100
MHz. The PR -37 is
a slim
-body
probe
of
precision
lightweight construction.
A
three
position
switch
selects 10:1
or direct
modes, or a
reference position that grounds
the tip through
a
9-megohm
resistor.
The
52"
coaxial
cable is extremely
flexible.
Accessories included
with the PR -37 are a
spring
-loaded retractable
tip cover,
insulating
tip
BNC
tip adapter,
IC tip and an
insulated
compensation
capacitor
adjustment tool. The
insulating tip
is
designed
for
probing
dense
solid-state circuitry with
little
danger
of
shorting nearby
components.
The BNC
adapter tip converts the
probe
tip
into
a push -
on BNC fitting,
ideal
for interface
with test
points
or
output
jacks. The IC tip
guides
the
probe
contact
into an y pin
of a
standard
DIP,
making it
almost
impossible to
short two
pins
of
an IC.
The PR
-37
is
available in
both
grey
and
red
colors.
Probes of different
colors are
particularly
useful with
a dual
-trace
scope
for
instant
identification
of the channel
to
which
a
probe is
connected. The
PR
-37 and
acces-
sories
come in convenient
zippered
vinyl
case.
Model PR
-37G
is
grey and PR
-37R is red.
OPERATION
By
setting the selector switch of
the
probe
to
the "1X"
position,
an unattenuated wave-
form
can
be observed. Note that bandwidth
is
10
MHz in
this position.
By
setting
the
switch to the "10X"
posi-
tion,
the
probe input
impedance is
increased
to
10
megohms and
the
waveform being observed
is
attenuated
10:1.
The "10X" position must
be used
above
10
MHz
and
whenever
the
loading effect of the probe may
disturb normal
operation
of
a circuit. Signal attenuation is
10:1 when
using the
standard
1 megohm input
impedance
(use
coaxial cable rather
than
the
probe when
terminated
into
50
ohms).
This
high
impedance
probe will cause very little
error in
measurements in circuits of
1
megohm
impedance
or less.
The "REF" positon of
the probe
selector
switch
opens
the probe
input
and
grounds the
oscilloscope
input,
allowing convenient display
of reference level.
ADJUSTMENT
Set
the probe
selector
switch
to the "10X"
position. Connect probe to vertical input
of
oscilloscope. Use
the
oscilloscope's most sens-
itive
vertical
attenuator setting and, while
observing
a
1
kHz
or
10 kHz
square
wave
signal,
adjust the tr immer on
the probe with
an insulated screwdriver for best square wave
presentation; that is,
least overshoot, tilt,
and
rounding
off of square
wave.
SERVICING
The
probe is not
repairable. This includes
both
repairs to the main probe assembly and
replacement of
the special
type coaxial cable.
The impedance,
capacitance, and
bandwidth
characteristics of the probe are very
critical,
and can only
be
assured by assembly at
the
factory. Servicing consists
of
probe
compen-
sation
adjustment
and replacement of those
items listed
in
the parts list.
14

CONTROLS & INDICATORS
(Refer to
Fig. 4)
Unless otherwise stated,
all information in
this
section
applies equally to
Models 1474,
1479,
1479A, and
1479B.
GENERAL CONTROLS
(1-13)
1.
MODE Switch.
Four -position lever
switch;
selects the
basic operating modes
of the
oscilloscope.
CH
A Only the
input signal to Channel
A is
displayed
as
a
single trace.
Fig.
4. Front Panel
Controls and
Indicators.
15
CH B Only the input signal
to
Channel
B
is displayed
as a single trace.
DUAL Dual -trace
operation; both
the
Channel A
and Channel B input
signals are
displayed on
two sep-
arate traces.