SECTION 5
RECALIBRATION
PROCEDURE
NOTE
Tolerances
and
accuracies
as
stated
in
Specifica
tions
section
and
the
Recalibration
Procedure
of
this
manual
apply
only
to
Type
575
instruments
above
serial
number
8030.
INTRODUCTION
The
following
equipment
is
required for
the
complete
cali
bration
of
your
instrument.
1.
A voltmeter
which
measures
de
voltage in
the
range
from
100
to
1700
volts
with an
accuracy
of
3%.
2.
De
voltmenter
such
as
the
Fluke
Model
803
or
the
Electro
Instruments Model
Eitronic 880.
Required
characteristics:
Input
resistance
at
least
1
megohm.
Accuracy
at
least
±1%
of
reading
between 0.1
volt and
5
volts.
3.
A
variable-voltage
transformer
capable
of
supplying
6.5
amperes
at
105
to
125
volts,
rms.
4.
An
oscilloscope
capable of
displaying
a
low-frequency
waveform
with
an
amplitude
of
about
10 mv,
peak-to-peak.
5.
A
resistance
bridge
capable
of
measuring resistances
from
1 ohm
to
500
kilohms.
The
resistance
bridge
accuracy
must
be
capable
of
insuring
that
the
resistor
is
within
1%
of
its
proper value.
6.
A small, non-metallic
screwdriver.
NOTE
Steps
5
and
6
should
be
performed
in
the
sequence
given.
Other
steps
may
be
performed
in
any
se
quence.
Unless
otherwise
stated,
all
adjustments
are
to
be
made
at
design
center
line
voltage
(117
v).
1.
Checking
the
Step
Selector
Switch
Connect
the
resistance
bridge
between
the
wire
running
from
the STEP
SELECTOR
switch
to
the
POLARITY
switch
and
the
wire
running from
the
front
wafer
to
the
middle wafer
on
top
of
the
STEP
SELECTOR
switch.
Read
resistance
values
as
shown
in
Table
5-1,
and
record
percentage
error
at
each
position
of
the STEP
SELECTOR
switch.
2.
Checking
the
Series
Resistor
Switch
Set
the
STEP
SELECTOR
switch
to
.01
VOLTS/STEP
and
Transistor
Selector
Switch
to
TRANSISTOR
A.
Connect
the
resistance
bridge
between
binding posts
B
and
E
on
the
left
side
of
the
test
panel.
Compare
each
resistance
value
on
the
SERIES RESISTOR
switch
with
the
resistance
reading
of
the
resistance
bridge
(±5%).
There
is
approximately
0.1
fl
resistance
in
series
with
the
SERIES
RESISTOR
switch
which
may
make
the
lower
resistance
readings
appear slightly
high.
The
0.1
fl
of resistance
is
made
up
of
wiring
and
switch contact
resistance.
TABLE
5-1
STEP
SELECTOR
(MA
PER
STEP)
Resistance
±1%
.001
500
k
.002
250
k
.005
100
k
.01
50 k
.02
25
k
.05
10
k
.1
5k
.2
2.5
k
.5
1
k
1
500
fl
2
250
a
5
ioo
a
10
50
fl
20
25 fl
50
lOfl
100
5
fl
200
2.5
fl
3.
Checking
the
Dissipation
Limiting
Resistor Switch
Connect
the
resistance
bridge
between
binding
post
C
on
the left
side
of
the
test
panel
and
the
white-brown-red
wire
on
top
of
the
Collector
Sweep
POLARITY switch.
Set
the
Collector
Sweep
POLARITY
switch
between
detents.
Measure
the
resistance
in
each
position
at
the
DISSIPATION
LIMITING
RESISTOR
switch.
Each
measured
resistance
should
agree
with
the
value indicated (zt5%).
4.
Power
Supply
All
voltage
test
points
are brought
out to
pin
jacks
on the
sides
of
the
lower
deck.
a.
Turn
the
instrument
on
and
allow
a
ten
minute
warm-up
period.
After
the
ten
minute
warm-up
period,
connect
the
precision
voltmeter
between
the
junction
of
R302
and
R303
and
ground (these
resistors
are
located
on
the
Horizontal
VOLTS/DIV
switch).
Adjust
—
150
V
Adj
for
exactly
—
5v
as
read on
the
voltmeter.
Measure
the
voltages
and record
the
percentage
of
error
at the
other
resistor
junctions
on
the
voltage
divider
(see
Table
5-2).
These
errors
will
be
taken
into account
when
calibrating
the
vertical
and
horizontal
amplifiers.
TABLE
5-2
Measure
between
ground
and
junction
of:
Correct
reading
in
volts
R303
and
R304
—
2
R304
and
R305
-1
R305
and
R306
-0.5
R306
and
R307
-0.2
R307
and
R308
-0.1
5-1
Summary of Contents for 175
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