Tektronix TYPE L User manual
INSTRUCTION
MANUAL
Tektronix,
Inc.
S.W.
Millikan
Way
•
P.
O.
Box
500
•
Beaverton,
Oregon
•
Phone
Ml
4-0161
•
Cable :
Tektronix
Tektronix
International
A.G.
Terra enweg
1A
•
Zug,
Switzerland
•
PH.
042-49192
•
Cable:
Tekintag,
Zug
Switzerland
•
Telex
53.574
070-336
All
Tektronix
in trument
a
re
warranted
again t
defective
material
and
workman
hip
for
one
year.
Tektronix
tran former ,
manufactured
in
our
own
plant,
are
war
ranted
for
the
life
of
the
in trument.
Any
que tion
with
re pect
to
the
war
ranty
mentioned
above
hould
be
taken
up
with
your
Tektronix
Field
Engineer.
Tektronix
repair
and
replacement-part
ervice
i
geared
directly
to
the
field,
there
fore
all
reque t
for
repair
and
replace
ment
part
hould
be
directed
to
the
Tek
tronix
Field
Office
or
Repre entative
in
your
area.
Thi
procedure
will
a ure
you
the
fa te t
po ible
ervice.
Plea e
include
the
in trument
Type
and
Serial
number
with
all
reque t
for
part
or
ervice.
Specification
and
price
change
priv
ilege
re erved.
Copyright
©
1962
by
Tektronix,
Inc.,
Beaverton,
Oregon.
Printed
in
the
United
State
of
America.
All
right
re erved.
Content
of
thi
publication
may
not
be
re
produced
in
any
form
without
permi ion
of
the
copyright
owner.
http://manoman.sqhill.com
WARRANTY
01X1
1
CHARACTERISTICS
General
Information
The
Type
L
Plug-In
is
a
fast-rise,
high
gain,
calibrated
preamplifier
designed
for
use
with
the
Tektronix
530-,
5 0-,
550-
and
*580-
Series
oscilloscopes.
The
unit
contains
a
fast
rise
d
c
amplifier
similar
to
the
Type
K
Plug
*Type
81
Plug-In
adaptor
must
be
used
with
the
580-Series
Oscilloscopes.
**Nanoseconds
are
10~9
seconds.
In
Unit,
plus
a
fast-rise
high-gain
ac
amplifier
which
may
be
used
to
increase
the
sensitivity
by
a
factor
of
10.
This
instrument
was
adjusted
at
the
factory
for
best
transient
response.
The
L
Unit
alone
has
a
risetime
of
6
nanoseconds
in
AC
or
TABLE
1-1.
TRANSIENT
RESPONSE
AND
BANDPASS
Type
RISETIME
in
nanoseconds
**
BANDPASS
L
AC-DC
Unit
switch
AC
or
DC
X10
GAIN
AC
DC
AC
X10
GAIN
AC
Oscilloscope
Type:
70
70
DC
to
5MC
3
cps
to
5MC
3
cps
to
5MC
532
5 1/5 1A
5 3/5 3A
5 5/5 5A
555
12
1
DC
to
30MC
3
cps
to
30MC
3cps
to
2 MC
531/531A
533/533A
535/535A
23
32
DC
to
15MC
3cps
to
15MC
3cps
to
11MC
*581
*585
12
1
DC
to
30MC
3
cps
to
30
MC
3cps
to
2 MC
551
1
16
DC
to
25MC
3cps
to
25MC
3cps
to
22MC
536
32
35
DC
to
11MC
3cps
to
11MC
3cps
to
10MC
With
X10
probes
(Types
P6017,
P6000,
P510,
P 10)
minimum
AC
response
is
reduced
to
0.3
cps.
AA
Characteristics
-
Type
L
Plug-In
1-1
DC
and
10
nanoseconds
in
X10
GAIN
AC.
Table
1-1
summarizes
risetimes
and
frequency
responses
available
when
the
L
Unit
is
used
in
combination
with
various
types
of
Tektronix
oscilloscopes.
Vertical
Deflection
Factors
AC
or
DC
position
of
AC-DC
switch:
0.05
to
20
volts
per
centimeter
in
nine
calibrated
steps;
also
continuously
variable
(uncalibrated)
between
steps,
and
up
to
50
volts
per
centimeter.
X10
GAIN
AC
position
of
AC-DC
switch:
0.005
to
2
volts
per
centimeter
in
nine
calibrated
steps;
also
continuously
variable
(uncalibrated)
between
steps,
and
up
to
5
volts
per
centimeter.
Step
Attenuator
(VOLTS/CM
switch)
Accurac
Within
3%
of
front-panel
reading
for
all
positions
of
VOLTS/CM
switch.
Input
Impedance
Characteristics
Type
L
Plug-In
Unit:
1
Megohm
shunted
by
20
picofarads.
Type
P6017
Probe:
10
Megohms
shunted
by
1
picofarads.
Type
P6000
Probe:
10
Megohms
shunted
by
11.5
picofarads.
Type
P510
Probe:
10
Megohms
shunted
by
1
picofarads.
Type
P 10
Probe:
10
Megohms
shunted
by
8
picofarads.
Maximum
Allowable
Combined
DC
and
Peak
AC
Input
600
volts,
ac-coupled.
Mechanical
Construction:
Aluminum-alloy
chassis.
Finish:
Photoetched,
anodized
front
panel.
Weight:
Approximately
5
pounds.
1-2
Characteristics
-
Type
L
Plug-In
AA
01X1
2
OPERATING
INSTRUCTIONS
Markings
and
Functions
of
Controls
The
functions
of
the
controls
should
be
understood
before
operating
the
L
Unit.
This
section
of
the
Instruction
Manual
is
intended
to
aid
in
initially
putting
the
instrument
into
operation
and
to
serve
as
a
brief
reference
guide.
Figure
2-1
shows
the
front-panel
con
trols,
connectors
and
adjustments
of
the
Type
L
Plug-In
Unit
and
describes
their
functions.
In
this
Manual,
control
and
adjustment
mark
ings
are
given
as
printed
on
the
instruments,
with
fully
capitalized
words
used
for
front
panel
markings,
and
first-letters
capitalized
for
names
of
internal
adjustments.
Examples:
VERTICAL
POSITION
control;
H.F.
Peaking
control.
On
the
front
panel
of
the
L
Unit
,
red
markings
are
related
to
the
red
VARIABLE
knob,
blue
and
black
markings
are
related
to
the
black
knobs.
The
black-numbered
scale
around
the
VOLTS/CM
switch
is
used
when
the
AC-DC
switch
is
in
AC
or
DC
position,
and
the
blue
scale
is
used
when
the
AC-DC
switch
is
in
X10
GAIN
AC
position.
In
the
following
procedures,
oscilloscope
controls
are
called
by
the
names
usually
applied
to
them
on
the
scopes
with
which
the
Type
L
Unit
can
be
used.
Alternate
names
for
the
controls
are
given
in
parentheses.
First-Time
Operation
To
set
the
oscllloscope/Type
L
Plug-In
Unit
combination
in
operation
for
the
first
time
the
following
procedure
is
suggested:
1.
Insert
the
Type
L
Unit
into
the
plug-in
compartment
of
the
oscilloscope
and
tighten
it
with
the
securing
rod.
2.
Set
the
front-panel
controls
as
follows
(con
trols
not
mentioned
may
be
in
any
position):
Oscilloscope:
POWER
off
INTENSITY
fully
counter
clockwise
HORIZONTAL
DISPLAY
NORMAL
("
A"
,
INTERNAL
SWEEP)
MAGNIFIER
(5X
MAG.)
OFF
Main
Sweep
Controls:
TIME/CM
.5
MILLISEC
VARIABLE,
TIME/CM
CALIBRATED,
fully
clockwise
TRIGGER
SLOPE
-INT.
(-)
TRIGGERING
MODE
AC
(AC
SLOW)
(TRIGGERING
SOURCE)
(INT.)
STABILITY
fully
clockwise
TRIGGERING
LEVEL
fully
clockwise
Type
L
Plug-In
Unit:
AC-DC
DC
VOLTS/CM
.05
(black
numbers)
VARIABLE,
VOLTS/CM
CALIBRATED,
fully
clockwise
3.
Connect
the
power
cord
to
the
instrument
and
to
the
source
of
power.
.
Turn
ON
the
POWER
switch.
Allow
a
minute
for
the
filaments
to
heat
and
the
time-delay
relay
to
operate.
5.
Before
increasing
the
intensity,
center
the
trace
vertically
with
the
VERTICAL
POSITION
control,
using
the
Beam
Indicator
neons
of
the
oscilloscope
as
a
guide.
(When
both
vertical
AA
Operating
Instructions
-
Type
L
Plug-In
2-1
VOLTS/CM
—
Nine
-
po ition
witch
elect
calibrated
vertical
en itivitie
indicated
on
panel.
Black
number
u ed
for
AC
and
DC;
blue
number
for
x10
GAIN
AC.
VARIABLE
--
Control
provide
continuou ly
variable
attenuation
be
tween
tep
of
VOLTS/
CM
witch.
Extend
attenuation
to
provide
en itivity
to
50
V
/cm
i
n
AC
and
DC;
to
5
.
0v/cm
in
x
10
G
AIN
AC.
AG-DC--Thr
e
e
-
po ition
witch
provide
d
c
coupling
in
DC
po ition.
ac-
co
upling
in
x10
GAIN
AC
and
AG
po ition .
x10
GAIN
AC
po ition
al o
witche
x10
amplifier
into
circuit.
Ground--Connector
for
grounding
other
equip
ment
t
o
cha i
of
plug
in
unit.
INPUT
UHF
-
type
ignal
input
connector.
TYPE
L
PLUG-IN
UNIT
SERIAL
VARIABLE
VOLTS/CM
ATTEN.
GAIN
ADJUST
Screw
driver-
adju table
con
trol
eta
gain
of
main-
amplifier
ection
of
the
unit.
GAIN
ADJUSL--
Screwdriver
adju t
able
control
et
gain
of
X10
amplifier
ec
tion.
VERTICAL
POSITION
-
-
Control
o cillo cope
vertically.
po ition
di play
2-2
VERTICAL
foiinoiv
VARIABLE
BAL,
Screwdriver
ad
ju
table
control
bal
ance
main-amplifier
ection
o
that
u e
of
VARIABLE
control
doe
not
hill
o cillo cope
di play.
VARIABLE
ATTEN.
BAL,
-
Screwdriver
adju table
control
bal
ance
X
10
amplifier
out
put
o
that
u e
of
VARIABLE
control
doe
not
hift
o cillo cope
d
i
-
play.
Fig.
2'1.
Functtorts
of
front-panel
controls
and
connectors
of
the
Type
L
Plug
Jn
Unit.
Operating
Instructions
Ivpc
L
Plug-In
A.A
http://manoman.sqhill.com
Beam
Indicator
neons
are
unlit,
the
trace
is
approximately
centered.
6.
Rotate
the
INTENSITY
control
clockwise
until
the
free-running
trace
appears
on
the
crt.
Center
the
trace
with
the
vertical
and
horizontal
positioning
controls.
7.
Adjust
the
FOCUS,
ASTIGMATISM
and
INTENSITY
controls
to
obtain
a
sharp
trace
with
adequate
intensity.
8.
Let
the
instrument
warm
up
for
at
least
15
minutes
before
making
any
adjustment
changes
or
accurate
observations.
Variable
Attenuator
Balance
Adjustment
The
need
for
adjustment
of
the
VARIABLE
ATTEN.
BAL.
control
is
indicated
by
a
vertical
shift
in
the
position
of
the
trace
as
the
VARIABLE
(VOLTS/CM)
control
is
rotated.
The
Type
L
Unit
has
a
separate
VARIABLE
ATTEN.
BAL.
control
for
each
of
the
two
amplifiers
in
the
unit.
The
main
amplifier
section
VARIABLE
ATTEN.
BAL.
control
adjusts
the
de
balance
between
the
two
outputs
of
the
amplifier.
The
X10
VARIABLE
ATTEN.
BAL.
control
adjusts
the
d
c
level
of
the
X10
amplifier
output
to
match
that
of
the
First
Cathode
Follower,
so
that
the
trace
position
will
not
shift
when
changing
from
X10
GAIN
AC
to
either
of
the
other
positions
of
the
AC-DC
switch.
Check
these
adjustments
in
the
following
order:
1.
Set
the
front
panel
controls
as
previously
listed.
With
no
signal
applied
to
the
INPUT
of
the
plug-in
unit,
freerun
the
trace
with
the
STABILITY
and
TRIGGERING
LEVEL
con
trols
fully
clockwise.
Set
the
AC-DC
switch
at
AC.
Turn
the
VARIABLE
control
back
and
forth,
watching
the
CRT
for
a
shift
in
position
of
the
trace.
If
the
trace
moves
when
the
control
is
rotated,
adjust
the
upper
VARIABLE
ATTEN.
BAL.
control
until
the
trace
position
is
no
longer
affected
by
the
VARIABLE
control.
2.
Turn
the
AC-DC
switch
to
X10
GAIN
AC.
Check
the
d
c
balance
of
the
X10
amplifier
by
rotating
the
VARIABLE
control
back
and
forth.
If
the
trace
moves,
adjust
the
X10
VARIABLE
ATTEN.
BAL.
control
until
rotation
of
the
VARIABLE
control
no
longer
affects
the
position
of
the
trace.
Return
the
VARIABLE
control
to
the
CALIBRATED
position,
fully
clockwise.
Checking
Gain
Adjustment
Adjustment
of
the
vertical
gain
should
be
checked
frequently.
Aging
of
tubes
and
other
components
causes
a
slight
change
in
the
gain
characteristics
of
the
plug-in.
In
order
to
make
correct
voltage
measurements,
adjust
ment
of
the
gain
must
be
correct.
The
Type
L
Unit
has
two
screwdriver
adjust
ments
on
the
front
panel
for
setting
gain--one
for
each
amplifier
in
the
unit.
Checking
the
gain
is
done
in
two
steps:
1.
With
the
oscilloscope
and
L
Unit
controls
positioned
as
above,
set
the
oscilloscope
CALI
BRATOR
output
for
.2
VOLTS.
Be
sure
the
VARIABLE
(VOLTS/CM)
is
in
CALIBRATED
position.
Connect
a
lead
from
the
output
con
nector
of
the
CALIBRATOR
to
the
INPUT
connector
of
the
Type
L
Unit.
Adjust
the
STABILITY
and
TRIGGERING
LEVEL
controls
of
the
oscilloscope
for
a
stable
display
of
the
CALIBRATOR
square
wave.
The
peak-to-
peak
vertical
deflection
should
be
exactly
four
major
graticule
divisions
( cm).
If
incorrect,
adjust
the
upper
GAIN
ADJUST
control
with
a
small
screwdriver
to
obtain
the
proper
amplitude.
2.
With
all
other
controls
positioned
as
in
the
previous
step,
turn
the
CALIBRATOR
to
20
MILLIVOLTS
and
set
the
AC-DC
switch
in
the
X10
GAIN
AC
position.
Adjust
the
STABILITY
and
TRIGGERING
LEVEL
controls
to
obtain
a
stable
square-wave
display.
Check
the
waveform
for
exactly
major
graticule
divisions
( cm)
of
vertical
deflection.
If
the
amplitude
is
not
correct,
adjust
the
X10
GAIN
ADJUST
control
until
exactly
cm
peak-to-
peak
is
observed.
Remove
the
lead
from
the
L
Unit
INPUT.
INPUT
Coupling
For
measurement
of
de
voltage
levels
or
signal
-to-ground
voltages,
it
is
necessary
to
have
dc-coupling
throughout
the
measuring
instrument.
With
the
AC-DC
switch
in
DC
position,
the
oscilloscope/Type
L
Unit
com
bination
is
dc-coupled
throughout.
AA
Operating
Instructions
-
Type
L
Plug-In
2-3
However,
it
is
often
neither
necessary
nor
desirable
to
display
the
de
component
of
the
input
waveform.
A
capacitor
which
is
in
series
with
the
INPUT
connector
blocks
the
de
com
ponent
when
the
AC-DC
switch
is
in
either
the
AC
or
the
X10
GAIN
AC
position.
This
permits
viewing
of
the
ac
part
of
a
large
input
signal,
as
well
as
detailed
viewing
of
the
ac
part
of
any
signal
having
adc
component.
Connecting
to
the
Signal
Source
Stray
electric
and
magnetic
fields
picked
up
by
unshielded
connecting
cables
often
change
the
appearance
of
displayed
waveforms.
This
type
of
distortion
occurs
even
in
the
audio
frequency
range,
except
possibly
when
making
measurements
of
low-impedance
circuits.
In
general,
unshielded
leads
of
appreciable
length
are
not
suitable
for
connecting
the
input
signal
to
the
plug-in
INPUT.
Shields
of
leads
used
should
be
grounded
to
the
chassis
of
the
instru
ment
in
use.
Coaxial
cables
are
recommended
for
most
purposes.
In
broadband
applications,
it
is
usually
neces
sary
to
terminate
a
coaxial
cable
with
a
resistor
which
presents
a
resistance
equal
to
the
charac
teristic
impedance
of
the
cable.
This
prevents
the
production
of
high-frequency
damped
oscil
lation.
As
the
length
of
the
cable
is
increased
it
becomes
more
important
to
properly
ter
minate
the
cable.
The
termination
is
placed
at
the
oscilloscope
end
of
the
cable,
although
many
sources
require
an
additional
termination
at
the
source
end
as
well.
For
large
amplitude
signals
an
attenuator
may
be
included
in
the
connective
system
to
provide
an
oscilloscope
display
having
a
more
desirable
amplitude
than
would
be
possible
with
no
attenuation.
Cables,
attenuators
and
ter
minating
resistors
are
listed
in
the
Accessories
section
of
any
Tektron
i
x
oscilloscope
Instruction
Manual.
When
checking
the
instruments,
actual
operat
ing
conditions
should
be
simulated
as
nearly
as
possible.
For
example,
the
oscilloscope
should
work
into
a
load
impedance
similar
to
that
which
it
encounters
in
actual
use.
The
input
circuit
of
the
plug-in
may
some
times
produce
loading
of
the
signal
source.
At
the
INPUT
connector
of
the
Type
L,
the
impedance
of
the
input
circuit
is
equivalent
to
a
resistance
of
1
Megohm
shunted
with
a
capacitance
of
20
picofarads.
With
a
few
feet
of
shielded
cable,
the
capacitance
may
well
be
increased
to
100
picofarads.
Where
the
effects
of
these
resistive
and
capacitive
loads
is
significant,
a
probe
may
be
used
to
introduce
the
input
signal.
Use
of
Probes
An
attenuator
probe
reduces
both
capacitive
and
resistive
loading
of
the
signal
source
and
decreases
apparent
sensitivity
of
the
oscil
loscope.
Attenuation
by
the
probe
permits
observation
and
measurement
of
signal
voltages
in
excess
of
those
that
can
be
accepted
by
the
preamplifier
alone.
The
10X
probes
(P6017,
P6000,
P510A,
P 10)
supplied
with
the
oscilloscopes
accepting
letter
series
plug-ins
may
all
be
used
with
theL
Unit.
Input
characteristics
of
these
probes
are
listed
in
the
Characteristics
section
of
this
Manual.
Maximum
voltage
which
may
be
applied
to
the
probes
is
600
volts
dc-plus-peak-ac.
Exceeding
this
limit
may
result
in
damage
to
the
components
inside
the
probe.
The
P510A
Probe
can
be
used
only
from
DC
to
50MC,
due
to
the
tendency
for
the
probe
to
ring
at
50MC
and
above.
If
the
displayed
waveform
contains
high-
frequency
portions,
it
is
generally
necessary
to
clip
the
probe
ground
lead
to
the
chassis
of
the
equipment
being
checked.
Before
using
a
probe,
check
its
adjustment.
An
adjustable
capacitor
in
the
body
of
the
probe
is
used
to
compensate
for
differences
between
input
capacitances
of
various
instruments.
To
insure
the
accuracy
of
pulse
and
waveform
measurements,
the
probe
adjustment
should
be
checked
when
changing
oscilloscopes,
and
occasionally
when
used
with
any
scope.
Probe
Compensation
To
adjust
the
compensation
of
the
probe
to
the
instrument
combination
with
which
it
is
to
be
used,
the
following
procedure
is
suggested:
1.
Set
the
oscilloscope
and
plug-in
controls
as
listed
above
in
First-Time
Operation.
Turn
the
oscilloscope
CALIBRATOR
voltage
selector
to
2
VOLTS.
Allow
adequate
time
for
the
instru-
2-
Operating
Instructions
-
Type
L
Plug-In
AA
A
-
INCORRECT
COR
1
RECT
INCORRECT
Fig.
2-2.
Waveforms
for
adjustment
of
probe
compensation.
ment
to
warm
up
(15
min.)
after
the
POWER
has
been
turned
ON.
2.
Connect
the
probe
cable
to
the
INPUT
con
nector
of
the
L
Unit.
3.
Touch
the
probe
tip
to
the
CALIBRATOR
output
connector
and
adjust
the
STABILITY
and
TRIGGERING
LEVEL
controls
for
a
stable
display
of
the
waveform.
.
Adjust
the
probe
capacitor
for
a
flat
top
on
the
square
wave.
See
Figure
2-2
for
a
display
of
the
waveform.
The
Instruction
Manual
for
the
instrument
with
which
the
probe
was
supplied
shows
the
method
of
adjusting
the
particular
probe.
Voltage
Measurements
Two
types
of
voltage
measurements
may
be
made
with
an
oscilloscope/Type
L
Plug-In
Unit
combination:
(1)
peak-to-peak
voltage
of
a
displayed
waveform,
and
(2)
peak
voltage
of
a
waveform
with
respect
to
a
reference
voltage.
The
following
procedures
are
intended
to
show
general
methods
,
and
can
be
modified
to
suit
any
particular
application.
In
measuring
signal
amplitudes
it
is
important
to
remember
that
the
width
of
the
trace
may
be
an
appreciable
part
of
the
overall
measure
ment.
This
is
particularly
true
when
measuring
signals
of
small
amplitude.
All
measurements
should
be
consistently
made
from
the
same
part
of
the
trace
—
the
top,
center
or
bottom.
If
the
center
of
the
trace
is
used
for
one
reading,
it
should
be
used
for
all
subsequent
readings.
Notice
that
points
"a"
and
"b"
in
Figure
2-3
correspond
to
the
center
of
the
trace.
Measuring
Peak-to-Peak
Voltages
To
measure
the
peak-to-peak
voltage
of
a
particular
signal,
the
following
method
may
be
used:
1.
Set
the
AC-DC
switch
at
any
convenient
position.
Apply
the
voltage
signal
to
the
INPUT
connector
by
means
of
the
appropriate
cable
or
probe,
and
necessary
terminations
and
atten
uators.
Adjust
the
controls
of
the
oscilloscope
and
plug-in
to
display
the
signal
waveform
on
the
crt.
Use
as
large
an
amplitude
as
possible
without
exceeding
the
size
of
the
graticule.
Be
sure
the
VARIABLE
(VOLTS/CM)
control
is
Fig.
2-3.
Measurement
of
peak-to-peak
signal
amplitude.
2.
Using
the
graticule
markings,
determine
the
vertical
difference
in
centimeters
(major
graticule
divisions)
between
the
maximum
and
minimum
peaks
of
the
waveform.
3.
Multiply
the
graticule
measurement
by
the
setting
of
the
VOLTS/CM
switch.
Use
the
black
numbers
for
AC
or
DC,
and
the
blue
numbers
for
X10
GAIN
AC.
This
product
is
the
voltage
at
the
INPUT
connector.
.
If
an
attenuator
or
attenuator
probe
iB
used,
multiply
the
input
voltage
by
the
total
attenuation
factor
of
the
connective
system.
AA
Operating
Instructions
-
Type
L
Plug-In
2-5
5.
The
final
number
is
the
voltage
difference
between
the
maximum
and
minimum
peaks
of
the
input
signal.
DEFLECTION
x
VOLTS/CM
x
ATTENUATION
=
VOLTAGE.
For
example,
in
Figure
2-3,
the
vertical
deflection
between
"
a"
and
"
b"
is
.0
cm.
If
the
AC-DC
switch
is
at
AC,
the
VOLTS/CM
switch
at
.5
(black
numbers),
and
the
signal
is
applied
through
a
10X
probe,
the
voltage
calculation
would
be:
( .0
cm)
x
(0.5
VOLTS/CM)
x
(10)
=
20.0
volts.
Measuring
Peak-to-Reference
Voltages
It
is
often
desired
to
measure
the
voltage
of
a
waveform
with
respect
to
some
reference
voltage,
usually
ground.
This
may
be
done
as
follows:
1.
Set
the
AC-DC
switch
at
DC
position.
2.
Connect
the
appropriate
interconnecting
cable
or
probe
to
the
INPUT
connector,
using
the
necessary
attenuators
and
terminations.
3.
Adjust
the
controls
of
the
oscilloscope
and
plug-in
for
a
free-running
trace.
Be
sure
the
VARIABLE
(VOLTS/CM)
control
is
in
the
CALI
BRATED
position.
.
Touch
the
input
cable
to
the
oscilloscope
ground
terminal
or
to
the
reference
voltage
being
used.
Adjust
the
VERTICAL
POSITION
control
to
set
the
trace
at
some
convenient
reference
position
such
as
(b)
in
Figure
2- .
5.
Without
changing
the
position
of
any
controls
of
the
instrument,
remove
the
cable
from
the
reference
voltage
(ground)
and
connect
it
to
the
voltage
signal
source
to
be
measured.
Adjust
the
oscilloscope
triggering
controls
for
a
stable
display.
If
the
amplitude
of
the
signal
is
inconveniently
large
or
small,
reset
the
VOLTS/CM
switch
for
a
more
suitable
value
and
repeat
the
above
procedure.
6.
Determine
the
vertical
distance
on
the
oscil
loscope
graticule
between
the
waveform
peak
and
the
original
trace
position.
Recheck
the
reference
level.
7.
Calculate
the
d
c
voltage
level
in
the
same
manner
as
peak-to-peak
voltage
is
calculated:
DEFLECTION
x
VOLTS/CM
x
ATTENUAT1ON
=
VOLTAGE.
For
example,
in
Figure
2-
the
vertical
distance
between
"
a"
and
"
b"
is
cm.
If
the
reference
voltage
is
ground,
the
VOLTS/CM
switch
is
set
at
.2
and
the
total
attenuation
ratio
of
the
connecting
system
is
15:1,
the
voltage
calculation
would
be:
( cm)
x
(0.2
VOLTS/CM)
x
(15)
=
12
volts
above
ground,
or
+
12
volts.
2-6
Operating
Instructions
-
Type
L
Plug-In
AA
SECTION
3
CIRCUIT
DESCRIPTION
General
The
Type
L
Plug-In
Unit
is
a
fast-rise
preamplifier
incorporating
a
fast-rise
high-
gain
ac
amplifier
and
a
fast-rise
de
amplifier.
Maximum
ac
sensitivity
is
0.005
volt
per
centimeter,
and
maximum
de
sensitivity
is
0.05
volt
per
centimeter.
The
main
amplifier
of
the
Type
L
Unit
consists
of
a
Phase
Inverter
Stage
which
produces
X2
amplification,
preceded
and
fol
lowed
by
cathode
followers.
When
the
AC-DC
switch
is
in
X10
GAIN
AC
position,
a
X10
amplifier
is
placed
in
cascade
with
the
main
amplifier
of
the
unit.
Input
Circuit
Either
ac-
or
dc-coupling
from
the
signal
source
may
be
selected
with
the
AC-DC
switch,
SW5002.
In
DC
position,
the
signal
is
coupled
straight
through
to
the
VOLTS/CM
switch.
In
AC
or
X10
GAIN
AC
the
signal
passes
to
the
VOLTS/CM
switch
through
a
blocking
capacitor,
C5002,
which
removes
the
de
com
ponent.
In
addition,
the
X10
GAIN
AC
position
switches
the
X10
amplifier
into
the
circuit
and
increases
and
decouples
the
voltage
on
the
screen
of
the
Input
Cathode
Follower.
The
VOLTS/CM
switch,
SW5052,
inserts
fre
quency-compensated
attenuators
into
the
input
circuit.
The
nine-step
attenuator
has
voltage-attenuation
ratios
of
IX,
2X,
X,
10
X,
20
X,
0
X,
100
X,
200
X,
and
00
X,
to
produce
deflection
factors
of
.005,
.01,
.02,
.05,
.1,
.2,
.5,
1,
and
2
volts
per
centimeter
in
X10
GAIN
AC
and
.05,
.1,
.2,
.5,1,2,
5,
10
and
20
volts
per
centimeter
in
AC
or
DC.
When
the
attenuators
are
properly
adjusted,
the
effective
resistance
and
capaci
tance
at
the
INPUT
connector
remain
unchanged
as
the
attenuators
are
switched
in
the
circuit.
The
attenuators
are
frequency-compensated
voltage
dividers.
At
low
frequencies,
the
capacitors
have
a
high
impedance
and
their
effect
in
the
circuit
is
negligible--the
atten
uators
act
as
resistive
dividers
with
the
atten
uation
being
proportional
to
the
ratio
of
the
resistances.
As
the
frequency
of
the
input
signal
is
increased,
however,
the
impedance
of
the
capacitors
decreases
and
their
effect
in
the
circuit
becomes
more
pronounced.
For
high-
frequency
signals,
the
impedance
of
the
capaci
tors
is
low
in
comparison
to
the
resistance
of
the
circuit,
and
the
attenuators
become
capaci
tive
voltage
dividers.
For
these
frequencies,
the
degree
of
attenuation
is
inversely
proportional
to
the
ratio
of
the
capacitances.
A
variable
capacitor
in
each
attenuator
provides
a
method
for
adjusting
the
capacitance.
Each
attenuator
network
has
a
variable
capacitor
for
adjusting
the
input
capacitance
to
a
standard
value
of
20
pf
at
the
INPUT
connector
for
all
positions
of
the
VOLTS/CM
switch.
C5732
in
the
grid
circuit
of
V5832
is
used
to
standardize
the
unit
with
the
XI
network
switched
into
the
circuit.
The
trimmer
capacitor
at
the
input
of
each
of
the
other
attenuator
networks
adjusts
the
input
capacitance
of
the
attenuator
to
the
standard
value.
Frequency
compensation
of
each
attenuator
network
is
provided
by
the
trimmer
capacitor
near
the
attenuator
output.
Input
Cathode
Follower
The
First
Cathode
Follower,
V5832
provides
isolation
between
the
input
circuitry
and
the
amplification
circuits.
It
prevents
changes
in
the
amplifier
from
changing
the
input
charac
teristics
of
the
plug-in,
and
it
prevents
changes
in
the
source
or
attenuator
switching
from
affecting
the
operation
of
the
amplifiers
.
AA
Circuit
Description
-
Type
L
Plug-In
3-1
The
screen
grid
of
the
First
Cathode
Follower
is
at
-100
volts
with
only
the
main
amplifier
of
the
unit
in
operation.
When
the
X10
Ampli
fier
is
switched
into
the
circuit,
the
voltage
on
the
screen
is
increased
and
decoupled
through
the
decoupling
network,
R58O2
and
C5802.
This
serves
to
protect
the
X10
Amplifier
from
any
slight
variations
which
may
be
present
in
the
power
supply.
X10
Amplifier
The
X10
ac-coupled
amplifier
consists
of
two
stages
of
amplification,
V59 2
and
V60 2,
and
a
cathode-follower
output
stage,
V6132.
The
X10
GAIN
ADJUST
which
controls
the
amount
of
degeneration
in
the
cathode
circuit
of
V60 2
is
a
front-panel
screwdriver
adjust
ment.
This
control
regulates
the
gain
of
the
X10
Amplifier
to
adjust
for
changes
which
take
place
in
the
components.
For
calibrated
operation
it
is
set
for
a
gain
of
ten.
High-frequency
compensation
for
the
X10
amplifier
is
provided
by
the
series-shunt
peaking
coils
L59 2
and
L6012,
and
by
the
series
peaking
coils
L5902
and
L6112.
The
variable
inductors,
L5902,
L59 2
and
L6012,
provide
a
means
for
adjusting
the
circuits
for
optimum
high-frequency
response.
Low-frequency
peaking
for
the
X10
amplifier
is
provided
mainly
by
C6002A
and
C6002B
in
the
plate
circuits
of
V59 2and
V60 2.
With
their
associated
resistors
,
these
capacitors
form
a
low-frequency
"
boost"
network
to
com
pensate
for
the
low-frequency
attenuation
intro
duced
in
the
cathode
circuits
,
the
screen
circuits
,
and
the
RC
coupling
network
between
the
Second
Amplifier
and
the
Second
Cathode
Follower.
The
amount
of
capacitance
in
the
circuit
is
fixed,
however
the
amount
of
attenuation
can
be
varied
with
the
LOW
FREQ.
ADJ.
control,
R6182,
in
the
grid
circuit
of
V6132.
By
adjust
ing
the
attenuation
to
match
the
capacitance,
low-frequency
distortion
in
the
amplifier
is
eliminated.
A
diode
is
Included
in
the
cathode
circuit
of
the
First
Amplifier,
V59 2,
to
protect
the
electrolytic
bypass
capacitor,
C5972.
This
capacitor
could
be
damaged
if
the
cathode
circuit
voltage
went
highly
negative,
as
when
the
tube
is
removed
without
turning
off
the
power.
For
proper
operation
of
the
X10
amplifier,
it
is
important
that
the
Second
Amplifier,
V60 2,
be
operated
on
a
certain
portion
of
its
character
istic
curve.
To
allow
for
slight
changes
in
component
values
and
for
tube
differences,
a
V60 2
Cathode
Current
Adj.
control,
R5922,
is
provided
in
the
plate
circuit
of
V59 2.
The
function
of
this
adjustment
is
to
set
the
current
through
V60 2
by
adjusting
the
voltage
on
its
grid.
Correct
cathode
current
is
indicated
by
a
voltage
drop
of
55
volts
across
resistor
R6072.
The
output
voltage
of
the
X10
amplifier
must
be
the
same
as
the
output
voltage
of
the
First
Cathode
Follower
in
order
to
present
the
same
voltage
to
the
grid
of
V62 2
in
the
Phase
Inverter.
This
is
necessary
in
order
to
main
tain
balance
in
the
main
amplifier
of
the
plug-in
when
switching
the
X10
amplifier
into
or
out
of
the
circuit.
The
X10
VARIABLE
ATTEN.
BAL.
control,
R62 2,
in
the
grid
circuit
of
V6L32
is
a
front-panel
screwdriver
adjustment
which
is
used
to
set
the
bias
on
the
grid
of
V6132
so
that
the
cathode
voltage
will
have
the
proper
value.
Phase
Inverter
The
Phase
Inverter
Stage
composed
of
V62 2
and
V63 2
is
a
cathode-coupled
phase
Inverter
which
converts
a
single-ended
input
signal
into
a
push-pull
output
signal
and
provides
a
gain
of
two.
The
GAIN
ADJUST
control
(R6392)
in
the
cathode
circuit
of
the
Phase
Inverter
sets
the
gain
of
the
main
amplifier
of
the
plug-in
unit
to
correspond
with
the
front-panel
cali
bration.
This
control
is
a
front-panel
screw
driver
adjustment.
The
VARIABLE
(VOLTS/CM)
control,
R6352,
located
between
the
two
cathodes,
regulates
the
gain
of
the
stage
over
a
2.5-to-one
range
by
varying
the
amount
of
degeneration
in
the
cathode
circuit.
Maximum
gain
occurs
with
the
control
in
the
CALIBRATED
position.
If
the
no-signal
de
voltage
levels
on
the
Phase
Inverter
cathodes
are
not
equal,
current
will
flow
through
the
VARIABLE
resistor
causing
a
change
in
the
gain
of
signals
passing
through
the
stage.
Voltage
on
the
cathode
of
V63 2
may
be
adjusted
to
balance
that
of
V62 2,
eliminating
current
through
R6352.
This
is
3-2
Circuit
Description
-
Type
L
Plug-In
AA
done
with
the
VARIABLE
ATTEN.
BAL.
con
trol,
R6812,
which
adjusts
the
voltage
on
the
control
grid
of
V63 2,
thereby
regulating
current
through
the
tube
and
setting
the
voltage
on
the
cathode.
The
presence
of
current
through
R6352
is
easily
indicated
by
rotating
the
VARIABLE
control--if
current
is
present
its
magnitude
will
be
changed
by
rotation
of
the
control,
producing
a
shift
in
the
position
of
the
crt
trace.
The
VERTICAL
POSITION
control,
R6522,
and
the
Vert.
Pos.
Range
control,
R6572,
provide
for
vertical
positioning
of
the
crt
beam.
Each
of
these
controls
consists
of
two
potentiometers
connected
between
+
225
volts
and
ground.
The
center
tap
of
one
potentio
meter
of
each
control
is
connected
to
one
side
of
the
push-pull
circuit,
and
the
center
tap
of
the
other
is
connected
to
the
other
side
of
the
circuit.
The
potentiometers
are
wired
so
that
as
the
voltage
on
one
center
tap
increases,
the
voltage
on
the
other
center
tap
decreases.
Turning
these
controls
increases
the
d
c
level
on
the
grid
of
one
Driver
Cathode
Follower
while
decreasing
the
d
c
level
on
the
grid
of
the
other
Driver
C.F.
Since
the
following
stages
are
dc-coupled,
this
change
in
d
c
level
at
the
Driver
C.F.s
results
in
a
vertical
displacement
of
the
crt
beam.
Minimum
capacitive
loading
to
the
plate
circuit
of
the
Phase
Inverter
Stage
is
assured
by
the
two
sets
of
cathode
followers
at
the
output--the
Driver
C.F.s,
V6732
A
and
B,
and
the
Output
Stage
C.F.s,
V6632
A
and
B.
Output
Cathode
Followers
The
Output
Cathode
Followers
provide
a
low-impedance
signal
source
to
drive
the
circuit
capacitance
at
the
plug-in
interconnecting
socket.
This
cathode
follower
circuit
is
modified
by
the
addition
of
resistors
in
the
plate
circuits
and
capacitors
cross-connected
from
each
plate
to
the
opposite
cathode.
This
configuration
improves
the
high-frequency
balance
of
the
unit.
The
H.
F.
Peaking
control,
R6692
in
the
cathode
circuit
of
the
Output
C.F.s
varies
the
current
through
these
tubes.
For
best
high-frequency
response,
this
adjustment
matches
the
impedance
of
the
cathode
circuits
to
the
fixed
series
peaking
coils,
L6672
and
L6772.
AA
Circuit
Description
-
Type
L
Plug-In
3-3
01X1
MAINTENANCE
PREVENTIVE
MAINTENANCE
The
L
Unit
is
a
stable
instrument,
and
will
require
complete
calibration
very
infrequently.
However,
to
be
certain
that
the
unit
is
operat
ing
properly
at
all
times,
the
calibration
of
the
unit
should
be
checked
after
each
500-hour
period
of
operation
(or
every
six
months
if
the
unit
is
used
intermittently).
A
complete
step-by-step
procedure
for
calibrating
the
unit
and
checking
its
operation
is
given
in
the
Calibration
section
of
this
manual.
Visual
Inspection
Many
potential
and
existent
troubles
can
be
detected
by
a
visual
inspection
of
the
unit.
For
this
reason,
a
complete
visual
check
should
be
performed
every
time
the
unit
is
inoperative,
needs
repairs,
or
needs
recalibration.
Apparent
defects
may
include
loose
or
broken
connections,
damaged
connectors,
improperly
seated
tubes,
scorched
or
burned
parts,
and
broken
terminal
strips.
The
remedy
for
these
troubles
is
readily
apparent
except
in
the
case
of
heat-
damaged
parts.
Damage
to
parts
due
to
heat
is
often
the
result
of
other
less
apparent
troubles
in
the
unit.
It
is
essential
that
the
cause
of
overheating
be
found
before
replacing
the
damaged
parts.
COMPONENT
REPLACEMENT
The
procedures
for
replacing
most
parts
in
the
L
Unit
are
obvious
and
detailed
instruc
tions
are
not
required.
In
some
cases,
additional
information
will
aid
in
the
replacement
of
parts.
This
information
is
given
in
the
follow
ing
paragraphs.
Because
of
the
nature
of
the
instrument,
replacement
of
certain
parts
will
require
that
portions
of
the
instrument
be
calibrated
for
proper
operation.
Refer
to
the
Calibration
section
of
this
manual
for
the
procedures
required.
Switches
If
a
switch
is
found
to
be
defective
and
needs
to
be
repaired
or
replaced,
use
normal
care
in
unsoldering
and
disconnecting
leads
from
the
terminals.
Single
wafers
on
wafer-type
switches
are
not
normally
replaced.
If
a
wafer
is
defective,
the
entire
switch
should
be
replaced.
The
VOLTS/CM
switch
may
be
ordered
from
the
factory
either
unwired
or
with
parts
wired
in
place,
as
desired.
Refer
to
the
Parts
List
to
find
the
wired
and
unwired
part
numbers.
When
soldering
leads
to
a
wafer-type
switch,
do
not
let
solder
flow
around
and
beyond
the
rivet
on
the
switch
terminal.
The
spring
tension
of
the
switch
contact
may
be
destroyed
by
excess
solder.
Occasionally,
wafer
switches
become
erratic
because
of
accumulated
dust
or
other
foreign
material
on
the
contacts.
This
condition
may
be
corrected
by
using
one
of
the
cleaning
lubricating
products
available
from
electronics
parts
distributors.
Be
sure
to
leave
a
thin
layer
of
conductive
lubricant
on
the
contacts,
but
no
excess.
Remove
any
excess
lubricant
with
a
moderate
jet
of
compressed
air.
Ceramic
Terminal
Strips
Two
distinct
types
of
ceramic
strips
have
been
used
in
Tektronix
instruments.
The
earlier
type
mounted
on
the
chassis
by
means
of
#2-56
bolts
and
nuts.
The
later
type
is
mounted
with
snap-in
plastic
fittings.
Both
styles
are
shown
in
Figure
-1.
When
replacing
a
ceramic
terminal
strip
of
the
type
which
bolts
onto
the
chassis,
first
unsolder
all
connections,
then
unscrew
the
terminal
bolt
nuts
on
the
reverse
side
of
the
AA
Maintenance
-
Type
L
Plug-In
-1
chassis
and
remove
the
terminal
strip.
Screw
a
#2-56
nut
onto
each
bolt
of
the
new
strip,
positioning
the
nut
so
that
the
distance
between
the
bottom
of
the
nut
and
the
bottom
of
the
ceramic
strip
equals
the
height
at
which
you
wish
to
mount
the
strip
above
the
chassis.
Secure
the
nuts
to
the
bolts
with
a
drop
of
red
lacquer.
Insert
the
bolts
through
the
holes
in
the
chassis
where
the
original
strip
was
mounted,
placing
a
#2
starwasher
between
each
nut
and
the
chassis.
Place
a
second
set
of
#2
flatwashers
on
the
protruding
ends
of
the
bolts,
and
fasten
them
firmly
with
another
set
of
#2-56
nuts.
Place
a
drop
of
red
lacquer
over
each
of
the
second
set
of
nuts
after
fastening.
Fig.
-1.
Two
types
of
ceramic
strip
mountings.
A
ceramic
terminal
strip
mounted
with
snap-
in
plastic
fittings
is
most
easily
removed
by
unsoldering
all
connections
,
then
using
a
plastic
or
hard
rubber
mallet
to
tap
the
mounting
clips
out
of
the
chassis.
This
can
be
done
by
tapping
on
the
ends
of
the
clips
protruding
through
the
reverse
side
of
the
chassis.
When
a
new
strip
is
ordered,
the
mounting
clips
are
furnished
with
and
are
attached
to
the
strip.
New
spacers
need
not
be
ordered
because
the
original
spacers
can
be
used
two
or
three
times
before
they
become
too
loose
to
hold
the
clips
securely.
When
the
damaged
strip
and
clip
assembly
have
been
removed,
place
the
spacers
for
the
new
strip
assembly
into
the
holes
in
the
chassis.
Using
a
plastic
or
hard
rubber
mallet,
tap
the
ceramic
strip
lightly
above
the
mounting
clips
to
drive
the
pins
down
through
the
spacers.
Be
certain
that
the
clips
are
driven
down
to
the
spacers.
Using
a
pair
of
diagonal
cutters,
cut
off
the
excess
length
of
the
mounting
clips.
Soldering
Precautions
In
the
production
of
Tektronix
instruments,
a
special
silver-bearing
solder
is
used
to
establish
a
bond
to
the
ceramic
terminal
strips.
This
bond
may
be
broken
by
the
repeated
use
of
ordinary
tin-lead
solder,
or
by
the
appli
cation
of
too
much
heat.
Occasional
use
of
ordinary
solder
will
not
break
the
bond
however,
unless
too
much
heat
is
applied.
If
continued
maintenance
work
is
to
be
per
formed
on
Tektronix
instruments,it
is
advisable
to
have
a
stock
of
solder
containing
about
3%
silver.
This
type
of
solder
is
often
used
for
work
on
etched-circuit
boards
and
should
be
readily
available.
It
may
also
be
purchased
directly
from
Tektronix
in
one
pound
rolls
(part
number
251-51 ).
Because
of
the
shape
of
the
terminals
on
the
ceramic
terminal
strips,
the
soldering
iron
should
have
a
thin
wedge-shaped
tip.
This
allows
the
heat
to
be
applied
directly
to
the
solder
in
the
terminals
and
reduces
the
amount
of
heat
required.
It
is
important
to
use
as
little
heat
as
it
possible.
Do
not
use
force
or
twist
the
tip
of
the
soldering
iron
in
the
terminal
slot
as
this
may
chip
or
break
the
ceramic
strip.
Apply
only
enough
solder
to
cover
the
wires
adequately.
Do
not
attempt
to
fill
the
notches
with
solder.
When
soldering
to
terminal
pins
mounted
in
plastic,
it
is
necessary
to
use
some
form
of
"
heat
sink"
on
the
terminal
between
the
soldering
iron
and
the
plastic,
to
avoid
damaging
the
plastic.
A
pair
of
long-nosed
pliers
is
convenient
for
this
purpose.
REPLACEMENT
PARTS
Standard
Parts
Replacement
for
all
parts
used
in
the
Type
L
Unit
can
be
purchased
directly
from
Tektronix
at
current
net
prices.
Many
of
the
components,
however,
are
standard
electronic
parts
that
can
generally
be
obtained
locally
in
less
time
-2
Maintenance
-
Type
L
Plug-In
AA
than
required
to
obtain
them
from
the
factory.
Before
purchasing
a
part,
be
sure
to
consult
the
Parts
List
to
determine
the
tolerances
and
rating
required.
The
Parts
List
gives
the
values,
tolerances,
ratings,
and
Tektronix
part
number
of
all
components
used
in
the
instrument.
Special
Parts
In
addition
to
the
standard
electronic
com
ponents
mentioned
in
the
previous
paragraph,
special
parts
are
also
used.
These
parts
are
manufactured
or
selected
by
Tektronix
to
satisfy
particular
requirements,
or
are
manufactured
especially
for
Tektronix
by
other
companies.
These
parts,
indicated
by
asterisks
in
the
Parts
List,
and
most
mechanical
parts
should
be
ordered
directly
from
Tektronix
since
they
are
normally
difficult
or
impossible
to
obtain
from
other
sources.
All
parts
may
be
obtained
through
your
local
Tektronix
Field
Engineering
Office.
TROUBLESHOOTING
This
portion
of
the
manual
will
aid
you
in
troubleshooting
the
L
Unit
in
the
event
that
trouble
develops.
During
troubleshooting
work,
the
information
contained
in
this
section
should
be
correlated
with
information
in
other
sections
of
the
manual.
No
attempt
is
made
to
give
detailed
step-by-step
procedures
for
finding
the
cause
of
specific
troubles.
Instead,
an
attempt
is
made
to
outline
a
general
trouble
shooting
guide
which
can
be
used
to
locate
trouble
which
may
occur
in
the
instrument.
This
guide
provides
a
means
for
determining
the
cause
of
a
trouble
from
symptoms
observed
rather
than
from
detailed
voltage
or
resistance
measurements.
In
general,
a
troubleshooting
procedure
can
be
thought
of
as
consisting
of
two
parts,
circuit
isolation
and
circuit
troubleshooting.
The
first
step
involves
isolating
a
trouble
to
a
definite
part
of
the
circuit.
When
the
trouble
has
been
isolated,
detailed
checks
can
be
used
to
deter
mine
which
part
or
parts
are
causing
the
trouble.
In
the
following
troubleshooting
procedures,
it
is
assumed
that
the
oscilloscope
used
with
the
L
Unit
is
operating
correctly.
This
is
not
always
the
case.
Troubles
occuring
in
the
oscilloscope
can
usually
be
detected
by
sub
stituting
another
plug-in
unit
for
the
L
Unit
and
checking
for
proper
operation.
A
schematic
diagram
of
the
L
Unit
is
con
tained
in
the
rear
portion
of
this
manual.
The
reference
designation
of
each
component
is
shown
on
the
circuit
diagram,
as
well
as
important
voltages.
These
should
be
used
as
troubleshooting
aids.
The
Circuit
Description
may
prove
useful
when
troubleshooting
within
a
particular
circuit.
Switch
wafers
shown
on
the
schematic
diagram
are
coded
to
indicate
the
position
of
the
wafer
on
the
actual
switch.
The
number
portion
of
the
code
refers
to
the
wafer
number
on
the
switch
assembly,
wafers
being
numbered
from
the
front
of
the
switch
to
the
rear.
The
letters
F
and
R
indicate
whether
the
front
or
the
rear
of
the
wafer
is
used
to
perform
the
particular
switching
function.
All
wiring
used
in
the
L
Unit
i
s
color
coded
to
facilitate
circuit
tracing.
In
addition
,
filament
and
power-supply
leads
are
distinguishable
by
specific
color
codes.
All
power
supply
leads
follow
the
standard
RETMA
code.
Preliminar
Troubleshooting
Before
attempting
any
troubleshooting
work,
check
all
front-panel
controls
for
proper
settings.
If
in
doubt
as
to
the
settings
of
the
controls
,
refer
to
the
Operating
Instructions
section.
Make
a
careful
visual
check
of
the
instrument
and
the
input
connections.
A
source
of
trouble
can
often
be
detected
by
visual
means.
If
no
trouble
is
visible,
apply
an
input
signal
and
observe
the
CRT
for
proper
wave
shapes.
Adjust
the
front-panel
controls
to
see
the
effect
of
each.
The
normal
or
abnormal
operation
of
each
control
will
indicate
what
sort
of
trouble
is
encountered.
Once
the
symptoms
are
clearly
established,
the
faulty
circuit
can
usually
be
isolated
more
readily.
Circuit
failure
is
often
caused
by
tube
failure.
The
most
effective
method
of
checking
tubes
is
by
direct
substitution
with
tubes
which
are
known
to
be
good.
It
is
important,
how
ever,
that
these
tubes
be
returned
to
the
same
sockets
from
which
they
were
removed
unless
they
are
actually
defective.
Unnecessary
replacement
or
switching
of
tubes
will
often
necessitate
recalibration
of
the
instrument.
If
a
defective
tube
is
found
and
replaced,
but
all
of
the
trouble
is
not
eliminated,
check
the
components
through
which
the
tube
draws
AA
Maintenance
-
Type
L
Plug-In
-3
current.
Shorted
tubes
will
often
overload
plate-load
and
cathode
resistors.
Troubleshooting
Procedures
It
will
be
necessary
to
turn
the
oscilloscope
on
its
side
(opposite
the
L
Unit)
and
remove
the
side
plate
and
bottom
plate
to
reveal
the
circuitry
of
the
plug-in.
To
trace
the
circuits
completely
it
will
also
be
necessary
to
extend
the
L
Unit
partially
out
of
the
plug-in
compart
ment
with
an
EP
5
Plug-In
Extension.
The
first
step
in
troubleshooting
a
Type
L
Unit
is
to
determine
whether
the
trouble
is
being
produced
in
the
main
amplifier
section
or
the
X10
amplifier
section.
When
the
AC-DC
switch
is
in
either
the
AC
or
the
DC
position,
only
the
main
amplifier
of
the
unit
is
function
ing.
When
the
switch
is
in
the
X10
GAIN
AC
position,
the
X10
amplifier
is
connected
in
series
with
the
main
amplifier
section,
and
both
sections
are
functioning.
When
trouble
exists
only
in
the
X10
amplifier
section,
the
plug-in
unit
will
function
normally
when
the
AC-DC
switch
is
set
at
either
the
AC
or
the
DC
position.
When
trouble
exists
in
the
main
amplifier
section,
however,
it
will
be
apparent
in
all
three
positions
of
the
switch.
The
troubleshooting
procedures
that
follow
are
divided
into
sections
according
to
trouble
symptoms.
When
a
trouble
occurs
in
the
unit,
the
proper
troubleshooting
section
can
be
quickly
found.
1.
Loss
of
Trace
If
the
sweep
circuits
within
the
oscilloscope
are
functioning
properly,
a
loss
of
the
trace
can
only
be
produced
by
improper
vertical
positioning
voltages.
In
other
words,
the
trace
is
positioned
above
or
below
the
visible
vertical
range
of
the
crt.
To
center
the
beam
vertically
on
the
crt,
the
d
c
voltages
at
the
output
jacks
of
the
Inter
connecting
Plug
(pins
1
and
3)
must
be
essentially
equal
(within
a
fraction
of
a
volt).
As
little
as
a
0.2-volt
difference
between
these
two
points
will
position
the
beam
above
or
below
the
range
of
visibility.
The
d
c
voltages
at
the
output
jacks
depend
upon
the
d
c
balance
of
the
amplifier.
Since
the
amplifier
is
dc-coupled
from
the
Phase
Inverter
Stage
(V62 2-V63 2)
to
the
Output
Stage
(V6632),
a
component
failure
anywhere
between
these
two
points
can
unbalance
the
amplifier
and
cause
a
loss
of
the
trace.
A
d
c
unbalance
can
be
caused
by
defective
tubes
,
defective
cathode,
screen
or
plate
resistors,
shorted
or
leaky
capacitors,
open
peaking
coils,
and
incorrect
ratios
in
the
voltage
dividers.
When
the
X10
amplifier
is
connected
into
the
circuit,
the
Second
C.F.
(V6132)
is
dc-
coupled
to
V62 2
(the
input
side
of
the
Phase
Inverter
Stage).
Due
to
the
coupling
capacitor
(C6112)
between
V60 2
and
V6132,
the
Second
C.F.
is
the
only
stage
in
the
X10
amplifier
that
can
affect
the
de
balance
of
the
main
amplifier.
If
the
trace
is
present
in
the
main-
amplifier
positions
of
the
AC-DC
switch,
but
absent
when
the
switch
is
set
at
the
X10
GAIN
AC
position,
it
is
apparent
that
the
de
unbalance
is
produced
by
the
Second
C.F.
stage
in
the
preamplifier.
A
possible
cause
of
this
condition
is
an
improperly
adjusted
X10
VARIABLE
ATTEN.
BAL.
control,
R62 2.
If
the
trace
is
missing
in
all
positions
of
the
AC-DC
switch,
the
defect
will
probably
be
somewhere
within
the
main-amplifier
section.
A
step-by-step
isolation
procedure
can
then
be
employed
to
establish
the
defective
stage.
This
procedure
is
accomplished
by
shorting
together
corresponding
points
on
opposite
sides
of
the
amplifier
with
a
resistive
shorting
strap,
described
under
"
Equipment
Required"
in
the
Calibration
Procedure.
Start
at
the
output
jacks
and
work
back
toward
the
Phase
Inverter
Stage.
For
example,
when
the
output
jacks
are
shorted
together
the
voltages
at
these
points
will
be
equal
and
the
trace
will
appear
at
or
near
the
center
of
the
crt.
From
this
point,
the
shorting
strap
can
be
moved
back,
in
successive
steps
,
to
the
cathodes
of
the
Output
Stage,
the
grids
of
the
Output
Stage,
the
cathodes
of
the
Driver
C.F.,
the
grids
of
the
Driver
C.F.,
and
finally
to
the
grids
of
the
Phase
Inverter
Stage.
Following
this
procedure,
a
point
will
be
reached
where
the
trace
cannot
be
made
to
reappear
when
corresponding
sides
of
the
amplifier
are
shorted
together.
When
this
occurs,
the
defect
has
been
isolated
in
the
stage
in
which
these
points
are
located,
and
the
stage
can
then
-
Maintenance
-
Type
L
Plug-In
AA
be
investigated
to
locate
the
defective
components.
When
the
grids
of
the
Phase
Inverter
Stage
are
shorted
together,
the
effect
of
the
vertical
positioning
controls
must
be
considered.
In
addition
to
the
VERTICAL
POSITION
control,
the
Vert.
Poe.
Range
control
(R6572)
and
the
VARIABLE
ATTEN.
BAL.
control
(R6812)
have
a
pronounced
effect
on
the
vertical
beam
positioning.
An
improper
adjustment
of
either
or
both
of
these
controls
can
result
in
a
loss
of
the
trace.
There
is
a
possibility
that
the
loss
of
trace
may
be
due
to
a
defective
tube-heater
circuit.
This
condition
can
be
determined
by
observing
the
tubes
in
the
plug-in
unit
for
heater
glow.
If
no
glow
is
observed,
it
will
most
likely
be
caused
by
an
open
heater
in
one
or
more
of
the
tubes.
Other
possibilities,
however,
are
shorted
capacitor
C6952,
or
a
defective
resistor
at
the
low
end
of
the
string.
2.
Inabilit
to
position
the
trace
If
the
trace
is
visible
on
the
crt,
but
it
cannot
be
moved
with
the
VERTICAL
POSITION
control,
some
defect
that
is
rendering
this
control
inoperative
is
indicated.
If
the
trace
can
be
moved
with
the
Vert.
Poe.
Range
con
trol,
the
VERTICAL
POSITION
control
is
probably
defective.
If
the
trace
cannot
be
moved
with
the
Vert.
Pos.
Range
control,
however,
the
trouble
will
lie
in
some
circuit
following
the
Phase
Inverter
Stage.
The
trouble
could
be
an
open
H.F.
Peaking
control,
R6692,
or
short
between
correspondingly-opposite
sides
of
the
amplifier.
An
examination
of
the
lead
dress,
or
a
continuity
check
with
an
ohm
meter,
will
reveal
the
shorted
condition.
3.
No
vertical
deflection
If
the
horizontal
trace
is
present
on
the
crt,
but
the
vertical
signal
is
not
displayed,
an
open
circuit
somewhere
in
the
vertical
deflection
system
is
indicated.
However,
since
the
horizontal
trace
is
present,
the
defective
component
is
one
that
does
not
upset
the
de
balance.
*
If
the
trouble
is
originating
in
the
X10
amplifier,
the
defective
component
is
in
the
circuit
of
either
the
First
Amplifier
(V59 2)
or
the
Second
Amplifier
(V60 2).
Since
these
stages
are
ac-coupled
to
the
Second
C.F.
stage,
an
open
circuit
ahead
of
the
coupling
capacitor
will
not
affect
the
d
c
balance.
If
the
trouble
is
originating
in
the
main
amplifier
section,
it
can
be
isolated
to
either
the
Phase
Inverter
Stage
or
the
Output
Stage
with
the
VERTICAL
POSITION
control.
If
the
trace
can
be
moved
vertically,
a
defect
in
the
Phase
Inverter
Stage
is
indicated.
This
could
be
an
open
resistor
in
the
cathode
circuit,
or
an
open
screen
divider.
If
the
trace
cannot
be
moved
with
the
VERTICAL
POSITION
control,
the
H.F.
Peaking
control
(R6692)
in
the
Output
Stage
is
probably
open.
4.
Insufficient
vertical
gain
If
the
vertical
deflection
on
the
crt
no
longer
corresponds
to
the
calibrated
value,
a
change
in
the
gain
characteristics
of
the
plug-in
unit
is
indicated.
If
the
change
in
gain
is
very
slight,
as
will
usually
be
the
case,
the
unit
can
be
recalibrated
according
to
the
instructions
presented
in
Calibration
Procedure.
If
there
is
a
considerable
change
in
gain,
however,
a
change
of
tubes
or
circuit
components
will
be
required.
If
only
the
X10
amplifier
is
out
of
cali
bration,
the
First-
or
Second-Amplifier
stage
is
probably
at
fault.
Two
adjustments
associated
with
these
stages,
the
V60 2
Cathode-Current
Adj
(R5922),
and
the
X10GAIN
ADJUST
(R6052),
are
very
important.
Refer
to
the
Calibration
Procedure
for
the
proper
adjustment
of
these
controls.
If
the
main
amplifier
section
is
out
of
cali
bration,
the
Phase
Inverter
Stage
is
probably
at
fault.
It
is
important
to
note
that
the
12AU6
tubes
in
this
stage
are
selected
and
paired
for
filament
voltage
and
grid
bias.
Unstable
operation
may
be
encountered
if
standard
12AU6
tubes
are
used
as
replacements.
An
open
VARIABLE
control
(R6352)
will
greatly
decrease
the
gain
of
the
Phase
Inverter
Stage.
A
change
in
the
value
of
the
cathode
resistors,
or
in
the
value
of
the
screen
divider,
can
also
affect
the
gain.
5.
Waveform
Distortion
If
waveform
distortion
occurs,
first
check
to
see
which
positions
of
the
VOLTS/CM
switch
have
distortion.
If
the
distortion
occurs
on
one
AA
Maintenance
-
Type
L
Plug-In
-5
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