INTERNAL
ADJUSTMENTS PROCEDURE
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
107 (5 parts in 108 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
502 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
+15-volt test
point and
ground.
Adjust
R305
for a reading of +15 volts. Then check the
+5-volt,
—5.2-volt, and -10-volt supplies to be within 5%.
NOTE
i
f
the instrument is operated on the plug-in extender,
vhe
+5-vo!t supply may not regulate.
Time-Base
Frequency
Check
and
Adjustment.
Connect
the DC
502 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 106. 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
106
low. Maximum allowable frequency difference is 1
part
in 105
(5 parts
in 107 for the optional 5 MHz crystal).
Adjust C201
for
no drift.
+5 V Test,
R322
—10 V Test,
R330
+15
V
Test,
R345
1-MHz test
point
-5.2 V Test, R305,
C201,
R330
+15 V
Adjust
1-MHz
Clock Adjust
Summary of Contents for DC 502
Page 4: ...DC 502...
Page 24: ...39 39 Relocated on back of board SN B070000 REV MAY 1974...
Page 33: ...FIG 1 EXPLODED...
