Circuit
Description
—
Type 175
you
should
remove
the
strap
between
the
two
REMOTE
VOLTAGE-DRIVE
GROUND
REFERENCE
binding
posts
and
connect
a
lead
from
the
ungrounded
post
to the emitter
lead
of
the
transistor
itself.
CIRCUIT
DESCRIPTION
Block
Diagram
Fig.
6-6
shows
a
simplified
circuit
diagram of
the
Type
175
connected
to
the
Type 575
for
plotting
collector current
versus
collector-to-emitter
voltage
of
an
NPN
transistor.
Most
of the
switching
has
been
omitted
from
this
diagram.
Overall
operation
of
the
unit is
as follows: The
step
out
put
from
the
Type 575 Step Generator is applied through
pin
K
of
the
interconnecting plug
to
the Step
Amplifier
in
the Type
175.
The
Type
175
Step
Amplifier
applies
the
steps
to
the
base
of
the
transistor
under
test
while
the
Type
175
Collector
Sweep
circuit
sweeps
the collector
voltage
from
zero
to
a
peak
voltage determined
by
the
setting
of
the
Type
175
controls.
The
time
relationship
between
the
col
lector
sweeps
and
the
base
steps
is
the
same as in
the
Type
575
alone.
The
number
of
steps
per
family
and
the
number
of
steps
per
second
are
determined
by
the
setting
of
the
Type
575
controls.
Polarity
of
the
steps
is
determined
by
the
Type
175.
The
voltage
drop
across
R415
is
proportional
to
the
cur
rent
through
it.
This
voltage
is
applied
through
pins
H and
J
of
the
interconnecting
plug
to
the
Vertical
Amplifier
of
the Type 575.
The
voltage
difference
between
the
switch
arms
of
R315
and
R316 is proportional
to
the
collector-to-
emitter
voltage across the
transistor.
This
voltage is applied
through
pins
E
and
F
of
the
interconnecting
plug
to
the
Horizontal
Amplifier
of
the
Type
575.
(Both
the VERTICAL
CURRENT OR
VOLTAGE
PER
DIVISION
and the
HORI
ZONTAL
VOLTS/DIV.
switches
of
the
Type
575 are
in
the
EXT.
position for operation
with
the
Type
175
Adaptor.
Collector
Sweep
The
Collector
Sweep
circuit
in
the
Type
175 is essentially
the same
as
that
in
the
Type
575
except
for
current
and
voltage
capabilities.
Full-wave
rectification
of
the
60-cycle
line
voltage
produces
120
sweeps
per
second
from
0
to
20
or
0
to
100
volts
peak.
These
sweeps
may
be
applied
as
either
positive-going
or
negative-going
voltages to the
collector
of
either
of
two
transistors
under
test
by
means
of
switch-actuated
relays.
The
Collector
Sweep
circuit
is
capable
of
supplying
peak
currents
of
over
200 amperes
through
the
transistor
under
test
at
the
0-to-20
volt
range
of
the
PEAK
VOLTS
RANGE
switch
and
over
40
amperes
in
the
0-to-100
volt
range.
The
circuit
breaker
in
the
primary circuit of T702 is nominally
rated
at
8
amperes
rms,
but is
capable
of
carrying
consider
ably
higher
currents
for short
periods
of
time.
The
primary
voltage
of
T702
is
variable between
zero
and
line
voltage
by
means
of
the
PERCENT
OF PEAK
VOLTS
RANGE
con
trol.
This
provides
a
maximum
average
input
power
rating
of
about
1
kilowatt.
Again,
peak
power
can
surpass
this
average
by
several
times
for
short
periods.
In
one
of
the 0-100
positions
of
the
PEAK
VOLTS
RANGE
switch,
a
300-ohm
resistor
(R720)
is inserted
in
series
with
the
output
of
T702
as
a dissipation
limiting
resistor.
Ad
ditional
limiting
resistors
may be
added
externally,
if de
sired
(see
Operating
Instructions,
"Collector
Sweep
Block".)
The
internal
resistance
of
the
Collector
Sweep
circuit,
ex
clusive
of
the
current-sampling
resistor
(R415)
and
R720,
is
0.03
ohm
when
the
PEAK
VOLTS
RANGE switch is
in
the
0-20
position,
and
0.5 ohm
when
the PEAK
VOLTS
RANGE
switch
is
in
the 0-100
position.
Because
of
this low internal
impedance,
it is
possible,
in
the
more
sensitive
positions
of
the
VERTICAL
DISPLAY
switch and
with
the
C
and
E
ter
minals
shorted or
nearly
shorted,
to
dissipate
enough power
within
the
Type
175
to
cause
damage
to
the
components.
For
this
reason,
the
VERTICAL
DISPLAY
switch
should
always
be
in
such
a
position
that
the
maximum collector-current
signal
does
not
exceed
a
maximum
amplitude
of
about
five
screen diameters.
A
counterpart
for
V733
in
the
Type
575
is
not required
in
the
Type
175
because
currents
due
to
stray
capacitance
in
the
Type
175
are
negligible
compared
to
the high currents
being
measured.
Step
Amplifier
The
Step
Amplifier
in
the
Type
175
is virtually
the same
as
that
of
the
Type
575.
The
only
significant
differences
are
the
use
of
20-volt
floating
power
supplies
in
place
of
15-volt
power
supplies
and
the use
of
four
parallel-connected
tran
sistors
in
the
output
stage.
(The
output
of
the 20-volt
sup
plies
is
actually
about
25
volts
at
nominal
line
voltage.) The
Type
175
is
capable of
supplying
a
maximum
base
cur
rent
of
12
amperes
whereas
the
Type
575
supplies
a
maxi
mum base
current
of only
about
2.4
amperes.
The
20-volt
supplies
for
the
Step
Amplifier
are
shown
on
the
Power
Supply
schematic
diagram.
Diode-connected
transistors
are
used
in
the
negative
supply
to
handle
the
ad
ditional
current
which
must
flow
through
that
supply.
R244R and
R244S
reduce
the
transients
which
appear
at
the
base
of the transistor under test whenever the STEP
SELECTOR
switch
is
moved from
one
position
to
the
next.
They
are shorted
out
except
when
the
switch
is
between
positions.
MAINTENANCE
General
maintenance
information,
such
as
filter
cleaning,
parts
replacement
and
ordering,
and
general
troubleshooting
instructions
is
the
same
for
the
Type 175
as
for
the
Type
575.
Therefore,
the following
information
is concerned only
with
specific
troubleshooting
procedures
for
the Type
175
Step
Amplifier
and
Collector
Sweep
circuit
and
the
associ
ated
switches.
Troubleshooting
the
Step
Amplifier
Troubleshooting
the
Step
Amplifier
of
the
Type
175
can
be
accomplished
by
the
same
procedures
as
for
the
Type
575
(note,
however,
that
in
some
cases
corresponding
parts
6-4
@2
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 ...