Dynascan Corporation B+K PRECISION 1476 User manual

@L476
10 MHz,
TRIGGERED
SWEEP
Dua
l-T
race
Osci
Iloscope
@"o#6FmN

WARNING
Normal useof test equipmentexposes
you to a certain
amountof danger
from
electricalshockbecause testing
must often be performed
whereexposedvoltage
is
present.
Anelectricalshock
causingl0 milliamps
of current
to pass throughtheheartwill
stop most humanheartbeats.
Higher
vollages
pose
an even
greater
threat
because
such
voltages
canmoreeasily
produce
alethalcurrent.However,
voltage
aslow as 35volts DC
or AC RMSshouldbeconsidereddangerous
andhazardous
sinceit can
produce
alethal
currentundercertainconditions.Your normalworkhabitsshouldincludeallaccepted
practices
that will prevent contactwith exposedhighvoltage,and
that will steer
current
away from your heart in case
of accidentalcontact with a high voltage.You will
significantlyreducethe risk factor if you know and observethe following
safety
precautions:
1.
Don't exposehigh voltageneedlessly.Remove
housingsand covers only when
necessary.
Turnoff equipment
whilemaking
test
connections
inhighvoltagecircuits.
2.Use
an insulatedfloor material or a large,insulated
floor matto standon,andan
insulatedwork surfaceon which to placeequipment;and makecertain
suchsurfaces
are
not damp or wet.Whereinsulatedfloor surfaceis
not available,wear heavy
gloves.
3.Use the time-proven "one hand in the pocket" techniquewhile handling an
instrument
probe.
Beparticularly careful
to avoid
contacting
a nearby metal
object
thatcould
provide
a
goodground
return
path.
4.Always use an isolation transformer to power transformerless
"hot chassis"
equipment,whereonesideof the AC power lineis connecteddirectlyto thechassis.
This includesmostrecenttelevisionsetsandaudio
equipment.Without an isolation
transformer,
the chassis of suchequipmentmaybefloating
atlinevoltage
(120VAC,
60 Hz in USA),dependinguponwhichwaythe2-wireAC power
plug
isinserted.
Not
only does
this present a dangerous
shock
hazardif thechassis
istouched,
but damage
to test instrumentsor the equipmentundertest may resultfrom connecting
the
groundleadof some test instruments to a "hot" chassis.The ground lead
of most
oscilloscopesand most other test instrumentswith 3-wirepower plugs
is an earth
ground.
5.On testinstrumentsor anyequipmentwith a3-wireAC powerplug,
useonly a3-wire
outlet.Thisis asafetyfeatureto keepthehousing
or other
exposed
elementsatearth
ground.
6.If possible,
familiarize
yourself
with the equipmentbeing
tested
andthe locationof
its high voltage points. However, remember that high voltage may appearat
unexpected
points
in defectiveequipment.
7.Also rememberthat AC line voltage
is present
on some
powerinput circuit points
suchason-offswitches,fuses,
power
transformers,etc.,
even
when
the
equipment
is
turnedoff.
8.Neverworkalone.
Someone
shouldbe
nearbyto renderaid
if necessary.
Training
in
CPR
(cardio-pulmonary
resuscitation)
firstaidishighlyrecommended.

INSTRUCTION
MANUAL
FOR
B
& K.PRECISION
MODEL
L476
10 MHz,
TRIGGERED
SWEEP
DUAL."TRACE
OSCILLOSGOPE
@BMFffiN
6460 WestC.ortlandStreet
Chicago,Illinois 60635

TABLE OF CONTENTS
Page
INTRODUCTION . 4
FEATURES
SPECIFICATIONS
OPERATOR'S
CONTROIS, INDICATORS AND FACILITIES .
OPERATING INSTRUCTIONS
Initial StartingProcedure
Single-Trace
Waveform
Observation
CalibratedVoltageMeasurement
CalibratedTime Measurement
ExternalHorizontal Input (X-Y Operation)
Z-Axis lnput .
Dual-Trace
Waveform
Observation
DUAL-TRACE APPLICATIONS
Introduction ... ... 14
FrequencyDividerWaveforms ....l4
Dvide-by-8CircuitWaveforms ....14
DigitalCircuitTimeRelationships .......14
GatedRingingCircuit .....l4
DelaylineTests...'.... ........16
StereoAmplifierServicing .......16
VideoEquipmentServicing .......17
9
9
l0
ll
t2
t2
t2
26
26
27
28
29
29
SINGLETRACE APPLICATIONS
Introduction
VideoEquipment
Servicing
Sigral Tracing
andPeak-to-Peak VoltageReadings
Composite
Video WaveformAnalysis
SyncPulse Analysis
VITS (Vertical lnterval TestSigral)
Vectorscope
Operation
TELEVISION ALIGNMENT
Introduction
lmportance of SweepAligrrment
SweepAligrment Methods
Tuner Alignment
IF Alignment
ChromaAlignment
l8
l8
l9
l9
l9
2l
23

TABLE OF CONTENTS
page
FMRECEIVERALIGNMENT.. ....3I
PHASE
MEASUREMENT
FREQUENCYMEASUREMENT .... 33
SQUAREWAVE TESTING OF AMPLIFIERS
Introduction ...... 33
Testinghocedure ........34
AnalyzingtheWaveforms.... ....34
CIRCUIT DESCRIPTION
General ....38
VerticalPreamplifiers .....38
Mode
logic .. .. .. 38
VerticalAmplifier .......38
TriggerCircuit ....38
SyncAmplilierandlnverter
... ...38
AutoSweep ......40
HorizontalAmplifier .....4O
ChoppingOscillator ......4O
I VoltCalSignal ........40
PowerSuppty .....4O
BlockDagram ....50
I',IAINTENANCE
AND CALIBRATION.... ........ 40
WARRANTY
INSTRUCTIONS ..... 43
WARRANTY ........ 43
OPTIONALACCESSORIES... .....44
3l

The B & K-Precision
Model 1476Dual-Trace
Oscil-
loscope
is a laboratory-quality,
professional
instrument
for
observing
and measuring
waveformsin electronic
circuits.
Dual vertical
inputsare
provided
for simultaneousviewing
of two waveforms.
Low-frequency,low repetition rate
waveforms
arechopped at a 200
kHz rate to providefor
simultaneous
viewing.Alternatesweep of the two inputs
permits
simultaneous
viewingof high-speed,highrepetition-
ratewaveforrns.
The
dual-trace
feature,
together
with the l0 MHzband-
width, wide rangeof sweepspeeds,and high sensitivrt)
provided,
makethis theidealoscilloscope
for abroad range
of applications, includingtroubleshootingand repairing
electronicequipment,researchand development,and
laboratoryinstruction.
INTRODUCTION
FEATURES
DUALTRACE
FULLY
SOLIDSTATE
TRIGGERED
SWEEP
LARGE
SCREEN
CALIBRATED
VOLTAGESCALES
CALIBRATED
SWEEPSPEED
WIDEBANDWIDTH
WIDERANGEOF
SWEEPSPEEDS
Two input waveforms can be
viewed either singly or simul-
taneously,as
desired.
Only the cathode
ray tubeuses
a
filament. All other stagesuse
transistors,
diodes, FET's (field
effect transistors) and IC's.
The 1476's
stability
of waveform
pres€ntationsis beyondcompari-
son with non-triggered sweeP
oscilloscopes.
The sweeps
remain
at rest
until triggeredby thesignal
being observed,to assure
that
they are always synchronized.
Fully adjustable
trigger
threshold
allowsthe desired
portign of the
waveforms
to beused
for trigger-
ing. Waveforms can also be
synchronized
to an externalsync
trigger.
The 130mm (approx.
5.1inches)
diametercathoderay tube gives
easy-to-read
presentation
on an
8 x l0 cm rectangularviewing
area.
Accuratemeasurementof the
stantaneous
voltaeeson I Iln- dif-
ferent attenuator
rangesfor both
ChannelA andChannelB.
Accurate time measurements on
l8 differentranges.
DCto l0 MHz bandwidth
and
35
nSEC rise time assuredistortion-
free,high resolution
presentation
athighfrequencies.
Sweepspeed
rangeof 1pSEC/cm
to 0.5 SEC/cm provides every
speed
necessaryfor viewing wave-
formsfrom DCto l0 MHz.
EXPANDED
SCALE
HIGH
SENSITIVITY
VIDEO SYNC
VECTORSCOPE
CALIBRATION
SOURCE
Z-AXIS
INPUT
MECHANICAL
FEATURES
A five time rtragrification (5X) of
the horizontalsweepallowsclose-
up examinationof a portion of
the waveform.In addition,
the5X
magnification provides a maxi-
mum sweep speed of 0.2
gSEC/cm.
Permits
thelow-capacitance,high-
impedance, l0:I attenuation
probes
to beusedfor virtually all
measurements,thus assuringless
circuit
loading.
A built-in syncseparatorcircuit is
included specifically for viewing
television
signals. When using
VIDEO SYNC, verticai
sync
pulses
areautomaticallyselectedat sweep
times of 0.5 SEC/cm to 0.
1
mSEC/cm for viewing television
frames. Horizontalsyncpulses are
automatically selectedat sweep
timesof50
pSEC/cm
to I pSEC/cm
for viewingtelevisionlines.
The unit may be usedas
avector-
scopeto provide a color display
exactly asspeciiiedby color tele-
visionmanufacturers.
A built-in calibratedI volt peak-
to-peak square wave permits
checkingand recalibrationof the
vertical amplifierswithout addi-
tional
equipment.
Intensitymodulation
capability
in-
cludedfor timeor frequency
mar-
kers.Compatible
withTTL logic;
brightnessincreasesin logic high
state,decreasesin logic
low state.
Carrying handle with comfortable
moldedfingergripalsodoublesastilt
stand.Lockingdetenteach
22-l/2"
allowsadjustmentof viewing angle.
Rear feet support oscilloscopein
face-up
position
anddoubleascord
wrapfor storing
power
cord. Slotted
bezeloverfaceof CRT mountsstan-
dardoscilloscopecameraformaking
waveform
photographs.

SPECIFICATIONS
VERTICALAMPLIFIERS
(CH
A andCH
B) Video Sync Verticaland horizontal
syncs€parator
circuit providedsothat any portion of
composite
videowaveformcanbe
syn-
chronizedandexpanded
for viewing.
LINE (horiz.) and FRAME (vert.)
sync switched automatically by
SWEEPTIME/CM switch.
FRAME 0.5 SEC/cm to 0.1
mSEC/cm(vertical syncpulses).
LINE : 50
pSEC/cm
to I pSEC/cm
(horizontal
syncpulses).
HORIZONTAL AMPUFIER (Horizontal lnput through
CHB Input)
Deflection
Factor .01V/cm to 20V/cm.
Frequency
Response DC to I MHz (- 3 dB).
Input Resistance I megohm
(nominal).
InputCapacity 22 pF (t3 pF).
Maximum Input 300 V (DC + AC peak) or 600 V
Voltage p-p.
X-Y Operation With SWEEP TIMEICM switchin
CH B position, the CH A input
becomes
the
Y input (vertical)
and
the CH B input becomes the X
input (horizontal). TheCHB posi-
tion control becomesthehorizon-
tal position
control.
CALIBRATION VOLTACE
I V p-psquare
wave
(t 5%)
at line
frequency.
INTENSITY MODULATION
Voltage
Input Resistance
TTL logic-compatible,
highlogic -
increases
brightness;
low logic -
decreases
brightness.
l0 kO
(nominal).
POWER
REQUIREMENTS
Input 120
or 240
V AC, tlo7o, 5O/6OHz,
20 watts. (3-wire linecord,CSA-
approved for oscilloscopes.) See
Fig.
51.
PR-31,
PR-35,PR-36,
PR-37.
Combination
l0: I anddirect.
l0:l = l0 megohms,
18
pF.
Direct= I megohm,
120
pF.
BNC
Spring-loaded,
hook-ontip.
Deflection
Factor
Calibration
Accuracy
Frequency
Response
Risetime
Overshoot
Ringing
InputResistance
InputCapacity
Max.Input Voltage
Operating
Modes
ChopFrequency
ChannelSeparation
SweepSystem
SweepTime
SweepTimeAccuracy
Sweep
Magnification
HorizontalLinearity
TRIGGERING
Source
Slope
Triggering
Range
0.01 V/cm to 20 V/cm in I I
calibrated ranges in l-2-5 se-
quence.
Variable
between
ranges.
! 5%
on allranges.
DC:DCto l0 MHz
G3 dB)
AC:2Hz to l0 MHz
(-3 dB).
35nanoseconds.
3%or lessat I@ kHz squarewave
display.
3%or less
at 100kHz squarewave
display.
I megohm,
t 57o.
22
pF(t3 pF).
300 V (DC + AC peak) or 600 V
p'p.
Channel
A only.
ChannelBonly.
Dual-traceautomatically
chopped
at allsweeptimesof I mSicm and
slower; alternatetrace automati-
cally selected
for all fastersweep
times.
2OOkHz(t2Vo).
Betterthan60 dB@| kHz.
Triggeredandautomatic.In auto-
matic mode, sweepis obtained
without input sigral.
I pSEC/cm
to 0.5 SEC/cmin 18
calibrated ranges,in l-2-5 se-
quence.
Variable
betweenranges.
+ <q^
Obtainedby enlargingthe above
sweep
5 timesfrom center. Maxi-
mum sweep speedbecomes
0.2
gSEC/cm.
3%or less distortion.
INT and EXT (l V p-p
sensitivity).MODE switch selects
sourceofinternaltrigger;
theCHA
signalis the triggering
sourcein
the CH A andDUAL modes,
and
the CH B signal
is the triggering
sourceinthe
CHB mode.
Positive
andnegative,
continuous-
ly variable
level
control;
pull for
AUTO.
INT: 20Hz
to l0 MHz
(min.
I cm
deflectionas measured
on
cathoderay tube).
EXT:
DC to l0 MHz.
PROBES
Model
No.
Attenuation
Input lmpedances
Connector
Tip
SWEEPCIRCUITS
(Common
toCHA andCHB)

7
I
9
r0
12
Fig.|. Frontpanel
controls
andindicators.

OPERATOR'S
CONTROLS.
INDICATORS
AND FACILITIES
l.
2.
3.
4.
Cathode
Ray Tube(CRT).This is thescreen
onwhich
the
waveforms
are
viewed.
Scale. The 8 x l0 cm graticule providescalibration
marks for voltage (vertical) and time (horizontal)
rneasurements.
Pilot Lamp.Lights whenoscilloscopeistumed on.
SWEEP TIME/CM Switch. Horizontal sweep time
selector.Selectscalibratedsweep
timesof I pSEC/cm
(microsecondper centimeter)
to 0.5 SEC/cm in l8
steps.In the CH B position, this switch disables
the
internalsweep
generator
and
permits
theCH Binput to
provide
horizontalsweep.
CAL |.-P Terminal. Providescalibrated I volt
peak-to-peak
square
waveinput signalat thelinefrequen-
cy. Thisis used
for calibration of theverticalamplifier
attenuators.
<> POSITION Control. Rotatitin adiustshorizontal
position of traces
(both traces
when operatedin the
dualtracemode). Push-pull
switchselects5X magrifi-
cation when pulled out (PULL 5X MAG): normal
when
pushed
in.
TRIGGERING LEVEL Control. Syncleveladjustment
determines
points on waveform slope where sweep
starts;
(-) equals
mostnegative
point of triggering
and
(+) equalsmost positive point of triggering. Push-pull
switch selects automatic triggering when pulled out
(PULL AUTO). Whenautomatic
triggering,
a sweep
is
generated
evenwithout aninput signal.
EXT TRIG Jack.Input terminalsfor externaltrigger
signal.
SYNC Switch. Four-position lever switch with the
following
positions.
SLOPE.The SLOPE
positionsareused for viewingall
waveformsexcepttelevisioncomposite
videosigtals.
(+) Sweep is triggeredon positive-going slope of
waveform.
(-) Sweepis triggeredon negative-goingslope of
waveform.
VIDEO. In theVIDEO positions, thesync
pulses
of a
televisioncomposite
videosignalareusedto triggerthe
sweep;theverticalsync
pulses
(frame)
areautomatically
selected
lorsweeptimes of0.5SEC/cm to0.I mSEC/cm,
and horizontal sync pulses (line) are automatically
selected
for sweep
times
of 50pSEC/cm to 1prSEC/cm.
(+) Sweepis triggeredon positive-going
syncpulse.
(-) Sweepis triggered
on negative-going
syncpulse.
SOURCE Switch. Selects triggeringsource for the
sweep.
INT Sweepistriggeredby CHA sigrral
whenMODE
switchisin CHA or DUAL position.
Sweep is triggered by Channel B sigral when
MODEswitchisin CH B position.
EXT Sweepis triggeredby an external signalapplied
attheEXT TRIGjack 8.
Channel
B POSITIONControl. Vertical position adjust-
ment for Channel
B trace.Becomes
horizontal
position
adjustment
whenSWEEP
TIME/CM switch4 is in the
CH B position.
Channel B DC BAL Adjustment. Vertical DC Balance
adjustment
for ChannelB trace.
ChannelB INPUT Jack. Vertical input jack of Channel
B. Jack becomes external horizontal input when
SWEEP
TIME/CM switch 4 isin the CH B position.
CtrannelB DC-GNDAC Switch.
DC Directinput of ACandDCcomponent
of input
signal.
GND Openssigral path and groundsinput to vertical
amplifier. This provides a zero-signal
base
line,
the position ofwhich canbeusedasareference
whenperforming DC measurements.
AC Blocks DCcomponent
of input signal.
ChannelB. VOLTS/CM Switch. Vertical attenuator for
ChannelB. Verticalsensitivity is calibrated
in I I steps
from .01 to 20 volts per cm. This control adjusts
horizontal sensitivity when the SWEEP TIME/CM
switch
4 isin theCH B position.
MODE Switch. Three-positionleverswitch; selectsthe
basic
operatingmodesof the oscilloscope.
CH A Only the input signal to Channel A is dis-
playedasasingle
trace.
DUAL Dual-traceoperation; both the ChannelA and
Channel B input signalsare displayedon two
separate
traces.
CH B Only the input signal to Channel B is dis-
playedas
asingletrace.
17. ChannelA VOLTS/CM Switch. Vertical attenuator for
ChannelA. Vertical sensitivityis calibrated in I I steps,
from .01to 20volts
per
cm.
18. ChannelA DC-GNDAC Switch.
DC Direct input of AC andDC component of input
sigral.
GND Openssigrral
path and groundsinput to vertical
amplifier. This provides a zero-sigralbaseline,
the position of which canbeused asareference
when performing DCmeasurements.
AC BlocksDC componentof input signal.
19. ChannelA INPUT Jack.Verticalinputjack ofChannel
A.
l). Channel A DC BAL Adjustment. Vertical DC balance
adjustmentfor ChannelA trace.
21. Channel A POSITION Control. Vertical position ad-
justmentfor ChannelA trace.
22. FOCUS
Control.
INTENSITY Control. Clockwise
rotation increases
the
brightness
of trace.
FOWER
Switch. Turnsunit on andoff.
ll.
12.
13.
14.
5.
6.
7
15.
16.
E.
9.
23.
10.
24.

29.
30.
25.
26.
n.
28.
VARIABLE Control. Fine sweeptime adjustment.In
the extremeclockwiseposition (CAL), the sweep
time
iscalibrated.
CH B VARIABLE Control. CHB vertical attenuator
adiustment. Fine control of CHB vertical sensitivity'
In-the extreme clockwise(CAL) position, the vertical
attenrator iscalibrated.
CH A VARIABLE Control. CH A vertical attenuator
adjustment. Fine control of CHA vertical sensitivity-
In-the extreme clockwise(CAL) position, the vertical
attenuator
iscalibrated.
INT MOD Jack.Intensity modulation (Z'axis) input.
AC Line Cord (See Fig. 2). CSA-approved
for oscil-
loscopes.
Probe
(See
Fig.3). TheB & K-Precision
ModelPR-31
combination
l0: l/Direct probes
havebeen
designed
for usewith this oscilloscope.
However,
any probe
designed
for usewith an oscilloscope
having
anominal
input impedance
of I megohm
shuntedby 35 pF and
capable
of operation
upto 10
MHz,canbe
used.
31. Vector Overlay (Not Shorvn). Interchangeswith scale
for vectorscope operation.
CRT ROTATION
ADJUSTMENT
DC BALANCECONTROL
(One
oneach
side
)COMBINATION
FEET
AND CORD
WRAP
Fig.
2. Rear
andside
panel
facilities.
2829
--
1.
PULL APART
t-r,_tfj1-
1O:1
ATTENUATION
(PR-35)
PROEE
COMPENSATIONADJUSTMENT
(PR-31
)
Adlust probe compensation for best
squarewavedisplay while observing
signal
from cal J1 1V p-p ACK.
PROBE COMPENSATIONADJUSTMENT
2.ROTATE180"
3.
PUSH
BACK
TOGETHER
Fig.3. hobe details.