Maintenance
—Type
575
Fig.
4-4.
Grounding
tho
junction
of
rosittor*
R251
and R246
to
chock
operation
of
tho
Stop
Ampllfior Circuit.
these
conditions,
if
the
circuit
is
operating
correctly
the
volt
age
across
R246
should
increase from
zero
by .5 volts per
step
regardless
of
tho
position
of
the
STEP SELECTOR
switch.
This
means
that
with
12
steps
in
a
family, the last
step
should
bring
this
total
voltage
drop
across R246
to
6
volts. This
voltage
can
bo
observed
on
a
test
oscilloscope
connected
to
the
ungrounded side
of
R246.
If
the
circuit
operates
properly
in
all
but
one
or
two
positions
of
the
STEP
SELECTOR
switch,
you should
check
the
resistors
peculiar
to
these
positions.
If
you
place
the
BASE
STEP
GENERATOR
switch
in
the
OFF
position,
no
output
should
be
obtained
from
the
ampli
fier
and
the
voltage
measured
at
the
ungrounded side
of
R246
should
be
zero. (It
may be necessary
to
adjust the STEP
ZERO
and
ZERO
ADJ
controls
to
obtain
zero
voltage).
Also,
adjustment
of
either
the
STEP ZERO
or
ZERO
ADJ
controls
should
change the
voltage slightly
across
R246
if
the
circuit
is working
properly.
If
you obtain an
abnormal voltage
across
R246
under
these
conditions,
you
can
locate
the
defective
stoge
by using
the
STEP
ZERO
control
to
generate
a
signal
voltage.
The
change
in
voltage
produced
by
the
STEP
ZERO
control
can
then
be
traced
through
the
remainder
of
the circuit.
When
the
circuit
is operating
normally,
the voltage
change
al each
point
in
the
circuit
is
in
the order
of
one
volt
as
the
STEP
ZERO
control
is rotated between
its
limits.
When the
circuit
is
not
operating
properly,
the
voltage
change
will
be
much
greater,
however,
making
it relatively
easy
to
trace
the
volt
age
shift
through
the circuit.
When
a point
in
the
circuit
is
reached
where
the voltage does
not
change
as
the
STEP
ZERO control is
rotated,
this
will
locate
the
defective
stage.
If adjustment
of
the
STEP
ZERO
control
produces
more
than
approximately a
one-volt
change
in
the
voltage
across
R246,
resistor
R203
should
be
checked. A large
voltage
change
at
the
output
of
the
circuit
when
the
STEP
ZERO
control
is rotated
is
indicative
that
the feedback
circuit
is
not
operating.
If
the
entire
circuit
appears
to
operate
correctly
except
that
the
top
of tho
stairstep
waveform
at
the
output is
flat
tened
off
so
that
one
or
more
of
tho
slops
is
eliminated,
tho
rectifiers
for
both
power
supplies
in
the
step
amplifier
must
be
checked.
With
a
stairstep
waveform
of 12 stops,
a
maxi
mum
of
2.4
amperes
must
be
supplied
by
the power
supply.
If
the
power
supply
is unable to
supply
the required
current,
the
last
stops
of
each
waveform
will
simply
be
eliminated
and
the upper
portion
of
the
waveform
will
be
flattened
off.
If
the
circuit
appears
Io
be
operating
correctly
except
that
the
voltage
steps
across
R246
ore
more
or
less
than
the
.5
volts
which
is
normal,
resistors
R202
and
R203 must
be
chock
ed.
The
ratio
of
these
two
resistors
controls
the
amplitude
of
the
output
steps
from
the
step
amplifier.
Troubleshooting
the Collector Sweep Circuit
If
a
trouble
occurs in
the
collector
sweep
circuit,
it
will
generally
result
in
either
current
flow
through
the
current
measuring
resistor
under
no
load conditions,
insufficient
out
put
voltage,
or
insufficient output
current.
If both
insufficient
output
voltage
and
current
occur
simultaneously
the
trouble
is
probably
a defective
rectifier.
A
small
amount
of
current
flow
through
the
current mea
suring resistor with
no
load
on
the
output
of
the
circuit
is
generally
due
to
failure
of
V733
or
to
a
misadjustment
of
C706
or
C735.
See
Fig.
4-5.
The
circuitry
of
V733
is
de
signed
to
eliminate
current
flow
through
the
current
measur
ing resistor resulting from
current
flowing
in
the
output
ca
pacitance
of the
collector
sweep
circuit.
Consequently,
if
V733
should
fail,
current
flows
through the
current
measuring
4-8
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 ...
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Page 54: ...Recalibration Type 575 C706 Fig 5 3 Left Side View 5 6 ...
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Page 104: ...TYPE 575 TRANSISTOR CURVE TRACER ...
Page 108: ...OSCILLATOR 4OOV UNREG TYPE 575 TRAN5I5TOR CURVE TRACER AB ...
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