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ADJUSTMENT
OF INTERNAL
CONTROLS
Services Available
Tektronix,
Inc.
provides
complete instrument
repair
and
adjustment
at local Field
Service
Centers
and
at
the Factory
Service
Center.
Contact your
local
TEKTRONIX
Field
Office or representative
for further
information.
Test
Equipment
For
measurement
of the
power
supply
voltages, a
20,000
ohms/volt
VOM
will
give satisfactory
measurements. For
example,
Triplett
630
NA
multimeter.
For
1-MHz
frequency
measurement,
a
secondary
frequency
standard
or
other
frequency
source having
a
stability
of
at
least
5
parts
on 10^
(5
parts
in
10^
if
measuring
optional
5
MHz
crystal
output)
is
recommended
for
accuracy.
Also
recommended
is
a
test
oscilloscope
with
a
bandwidth
of
at least
1
MHz
and
a
stable triggering circuit
for
frequency-comparison measurement.
Procedure
NOTE
The performance of
this
instrument can
be check
at
any
temperature
within the
0°
C
to
+50°
C
range.
Make
any
adjustment
at a
temperature
between
+20°C and +30°C
(+68°
F
and
+86°F).
The
DC
501 can be
operated
either fully
installed
in a
TM
500
Series
Power Module
or
connected
to
a plug-in
extender
(TEKTRONIX
Part
No. 067-0645-01).
Power Supply Checks and
Adjustment.
Connect
the
voltmeter
between
the -M5-volt
test
point
and
ground.
Adjust
R305
for a
reading of
-M5
volts.
Then
check the
-i-5-volt,
—
5.2-volt,
and -10-volt
supplies to
be within 5%.
NOTE
If
the
instrument
is
operated
on
the piug-in extender,
the
+5
-VO
It
supply
may
not
regulate.
Time-Base Frequency
Check
and Adjustment.
Connect
the
DC
501
1-MHz
time
base reference
and
the
secondary
standard
to
the oscilloscope
as
shown. Adjust
the
oscillo-
scope
to display
several
complete
cycles.
To
determine
oscillator
error,
observe the
rate
of
horizontal
drift
of the displayed
waveform.
Waveform
moving
to
the
right
indicates that
the time-base
frequency
is
<1
MHz;
to the
left,
>
1
MHz. The
period
in
seconds
for
the
waveform
to
move
the
width
of
one
cycle
is
equal to
the
frequency
difference
in
parts
in
10®.
For example,
if
the
waveform
drifts
to
the
right at
a
rate
of
one
cycle's
width
every 10 seconds, the time-base
frequency
is
0.1 part
in
10®
low.
Maximum
allowable
frequency
difference
is
1
part
in
10®
(5
parts
in
10^
for
the optional
5
MHz
crystal).
Adjust
C201
for
no
drift.
Dispk
LEO
rear
segment d
maticafly
point.
Th<
are
suppn
overflow
is
Overfl
LED
indie
leading
dig
attempts:
than
seven
1-MHz
test
point
-5.2
V
R3«5
C201
DtSPLA'
Variable c
with
MEP
TERVAL
length
of
will
be;di
count
is
dte next
taken.
DU
varied
fr
(MIN)
tc
onds.
t
(ctockwisE
tinuous
d
by
press!
button,
3-2
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