Maintenance
—
Type
575
both
full
wave
rectifier
circuits
are
abnormal,
it
will
be
nec
essary
for you
to
trace
the
signal
back
toward
the
secondary
of
transformer
T601 in
order
to
determine
the
exact
cause
of
the
trouble.
If
the
outputs
of
the
rectifiers
are
normal,
you
should
then
check
the
waveform
at
the plates
of
the pulse
shaper
tubes,
V104B
and
V124B.
This
should
be
done
after
disabling
the
pulse
gating
circuit
by
removing
tube
V163.
The
pulses
at
the
plates
of
V104B and
V124B
should occur
at
either
a
120
or 240
cycle
rate
depending
upon the
position
of
the
STEPS/SEC
switch.
If
the waveform is
normal
check
V143A
and
its
cathode
circuit.
Replace
VI
63
at
the com
pletion
of this check.
Stairstep
Generator
If
a
trouble
in
the
stairstep
generator
section
results
in
no
output from
the
step generator,
a
clue
to
the
cause
of
the
trouble
can
be
obained by
measuring
the
plate
voltage
of
the
integrator
tube,
VI
71.
Usually
when
no
output is
ob
tained
from
the
step
generator,
the
voltage
at
the
plate
of
VI71
is
either
approximately
35 volts
or
more than
250
volts.
These
conditions
are discussed separately
in
the
following
pa
ragraphs.
If
the
voltage
at
the
plate
of
the
integrator
tube,
VI
71
is
approximately
35
volts,
the tube
is
not
being
allowed
to
per
form its
normal
step-up
action.
This
may
result from
defec
tive coupling diodes
(V172A
or V172B),
improper
operation
of
the
Schmitt
trigger circuit
(V155A
and
V155B), or
an
open
resistor
in
the
cathode
circuit
of
V143B.
The
coupling
diodes
may
be
checked
by
removing
tube
VI
63
and
observing
the
waveform
at
the control
grid
of
VI71.
Under
these
conditions
the
waveform
should
be
a
series
of
sharp
negative
spikes
approximately
6
volts
in
am
plitude.
The
coupling
diodes
are
operating
correctly
if
the
spikes
are present.
If the
spikes
disappear
when
VI
63
is
re
placed
in
its
socket,
the
Schmitt
trigger
circuit
is
not
in
the
condition
which
allows
the
integrator
circuit
to
perform
its
step-up
action
(V155A
cutoff
and
V155B
conducting). If
R186,
in
the
cathode
circuit
of
V143B
is
not
open,
the
trouble
prob
ably
is
V155B
or its
associated
circuitry.
If
the
plate
voltage
of
the
integrator
tube
is
more
than
250
volts
with
the
STEPS/FAMILY
control
fully clockwise, the
tube
is
cut
off.
If this
is
the
case,
rotate
the
STEPS/FAMILY
control
fully
counterclockwise
and
momentarily
ground
the
control
grid
of
VI
71.
If
the
voltage
at
the
plate
of
VI71
drops
and
remains
at
a
lower
level,
the
trouble
is
that
the
disconnect
diodes
(V142A and
V142B)
are
not
conducting
to
reset
the integrator
tube. Tube
V152
is
probably
at
fault
in
such
a
case.
If
the
voltage
at
the
plate
of
VI
71
does
not
decrease
and
remain
lower
after
the
control
grid
is
momentarily
grounded,
but
instead remains
at
about
275
volts,
the
integrator
tube
is
not
being
reset.
Since
practically
any
stage
in
the
stairstep
generator
can
produce this
condition
it
is
necessary
to
make
additional
checks
to
determine
the
exact
cause
of
the
trouble.
It
is
necessary
to
check
each
stage
individually
by
means
of
voltage
checks
at
important
points
in
the circuit.
The
inte
grator
stage
should
be
checked first
however.
With
approximately
275
volts
at
the
plate
of
VI71,
the
cathode
of
V163A
should
be
at
about
215 volts.
If
this
voltage
is
incorrect,
check
V163A
and
its
grid
and
cathode circuits.
If
the
voltage
at
the
cathode
of
V163A
is
correct,
the
stage
is
probably operating correctly and
you
should
then
check
the
voltage
at
the
cathode
of
V143B
with
the
STEPS/FAMILY
control
fully clockwise.
The
voltage
should
be
approximately
—
40
volts.
If
the
voltage
is
not
correct,
check
V143B
and
the
cathode circuit
of
V163A.
If
the
voltage
at
the
cathode
of
V143B
is
correct,
the
stage
is
probably operating normally
and
you
should
then
check
V155A
and
its
grid
and
cathode
circuits
for
troubles
which
may
not
allow
the
tube
to
conduct.
If
V155A
is
conducting,
(this
can
be
determined
by
measuring
the
plate
voltage
of
V155A.
.
.if
the
tube
is
conducting,
this
voltage
should
be
less
than
50
volts)
the
trouble
then
must
be
V163B
or
its
associated
circuitry.
If
it is
impossible
to
obtain
the
correct
number
of steps
in
each
stairstep
waveform,
the
trouble
will
probably
be
located
in
the
cathode circuit
of
V163A.
If
the
cathode
circuit
of
V163A
is
normal,
you
must
then
check
the
resistors
in
the
plate
circuit
of
V155A
and
the
grid
circuit
of
V155B.
Adjusting
The
Step Amplifier
A
trouble
occuring
in
any stage
in
the
step
amplifier
can
produce
virtually
the
same symptoms
as
a
trouble
occuring
in
any
other
stage.
For
this
reason,
it
is
probably best
to
troubleshoot
the
circuit
by
checking
each
stage
individually.
This
may
be
done
if
the
following
procedure
is
used.
The
+1
Amplifier
(V254,
V264,
and
V233B)
should
be
checked
first.
This
can
be
done
by
placing
the
POLARITY
switch
in
the
—
position
and
grounding
the control
grid
of
V254
by
placing
a
jumper
from
the
junction
of
R251
and
R246
to
ground.
Under
these conditions,
the
cathode
voltage
of
V233B
should
be
zero.
(It
may
be
necessary
to
adjust
the
-ADJ
control
to
obtain
this voltage.)
If
the
cathode
voltage
of
V233B
is
correct,
the
+1
Amplifier
circuit
is
probably
op
erating
normally.
You should,
however
check
resistor R238
in
the
cathode circuit
of
V233B
before
proceeding
to
the
next
circuit
check.
NOTE
You
should
leave
the
grid
of
V254
grounded
during
the circuit
checks
made
on
the
remainder
of
the
step
amplifier.
If
the cathode
voltage
of
V233B
is other
than
zero
volts
when
the
grid
of
V254
is
grounded,
the
+1
Amplifier
is
de
fective.
The
trouble
can
be
isolated
either
to
cathode
follow
er
V233B
or
to
the
difference
amplifier (V254
and
V264)
by
measuring
the
voltages
at
the
control
grid
of
V264
and
V233B.
The
voltage
at
the
grid
of
V264
should
be
approxi
mately
the
same
as
the
voltage
at
the
cathode
of
V233B
if
the
cathode
circuit of
V233B
is
normal. If the
grid
voltage
of
V233B
is
approximately
zero,
but
the
cathode
voltage
is
not,
V233B
should
be
replaced.
If
the
grid
voltage
of
V233B
is
not
approximately
zero,
the
difference
amplifier
stage
is
de
fective.
In
the
latter
case,
it
will
be necessary
to make
ad
ditional
voltage and
resistance
checks to
determine
the
exact
cause
of
the
trouble.
With
the
POLARITY
switch
in
the
—
position,
the
grid
of
V224 is
maintained
at
ground potential
by
the
+1
Amplifier.
This
causes
the
step
amplifier
to
function
as
a
voltage-regu
lated
power
supply
with
the
stairstep
voltage
waveform
from
the
step
generator
serving
as
the
reference
voltage. Under
4-7
Summary of Contents for 175
Page 4: ...VWTICM OINltAlO TRANSISTOR CUM TRACfR UB l COUlClO r hokizoniai VCKIJ O lUnK Hix M Type 575 z ...
Page 6: ...NOTES ...
Page 26: ...NOTES ...
Page 48: ...NOTES ...
Page 54: ...Recalibration Type 575 C706 Fig 5 3 Left Side View 5 6 ...
Page 56: ...NOTES ...
Page 100: ...INPUT AMPLIF1E ...
Page 104: ...TYPE 575 TRANSISTOR CURVE TRACER ...
Page 108: ...OSCILLATOR 4OOV UNREG TYPE 575 TRAN5I5TOR CURVE TRACER AB ...
Page 115: ... 300 ...
Page 119: ...Type 175 Tent S N 570 PARTS LIST CORRECTION Change to Q233 151 0137 00 2N21U8 MIO 298 1165 ...