Tektronix 511A, Инструкция по эксплуатации

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SECTION IV
MAINTENANCE AND ADJUSTMENT
Maintenance
CAUTION — VOLTAGES HIGH ENOUGH
TO BE DANGEROUS ARE PRESENT IN
THIS INSTRUMENT. SINCE MUCH MAIN ­
TENANCE MUST
OF
NECESSITY BE
WITH THE CASE REMOVED, GREAT
CARE SHOULD BE TAKEN. USE ONLY IN ­
SULATED TOOLS, STAND ON A DRY
FLOOR, AND IF POSSIBLE KEEP ONE
HAND IN YOUR POCKET.
REMOVAL OF THE CASE
Set the oscilloscope face downward on a padded flat
surface, remove the access panel jumper plugs and the
two screws in the bottom, then lift off the case.
CLEANING
CAUTION — REMOVE POWER CORD AND
GROUND HIGH
VOLTAGE
CIRCUITS BE­
FORE CLEANING IS UNDERTAKEN.
At regular intervals, depending on local conditions,
the dust should be removed from the interior of the Type
511-A by means of dry compressed air. Avoid a high
velocity air stream which might injure the instrument or
disturb adjustments. Persistent dirt may be removed
with a lint-free cloth, or if necessary, carbon tetrachlo ­
ride. Special attention should be given to the high volt ­
age circuits, including parts under the high voltage
cover shields, as excessive dust and moisture may
cause arcing.
Under normal conditions, the silver plated contacts of
the rotary switches should not require special attention.
In case they become tarnished, the contacts should be
cleaned by rotating the switch several times.
INSPECTION
A visual inspection is desirable while the Type 511-A
case is removed during cleaning.
1. Switches. Turn the rotary switches while observing
the contacts,
to
check contact
centering in each
index
position. Improperly centered contacts may be due to
the
switch becoming warped or twisted,
or
in
the case
of
S2 (SWEEP RANGE), to a loose shaft coupling.
CAUTION — AVOID PRESSURE ON THE
CONTACTS AS THEY ARE EASILY DAM ­
AGED.
2. Capacitors and Resistors. Inspect the oil filled and
electrolytic capacitors for leakage of oil or electrolyte,
replacing if necessary. The wax coating of paper tubu ­
lar capacitors may drip if the instrument has been over ­
heated by operating in a restricted space. This condition
usually does not indicate replacement. Composition re­
sistors should be checked for serious discoloration,
which would indicate excessive dissipation and there­
fore faulty operation. A moderate amount of discolora ­
tion is normal.
3. Connections. Loose screws or nuts should be
tightened. This is especially important when the screw
serves as an electrical connection. Corrosion of the
chassis and electronic components is unlikely under
normal conditions. It should be removed if evident, and
the cause corrected. If the instrument must be operated
in a corrosive atmosphere, it may be desirable to re­
move the tubes occasionally and clean the contact pins
with crocus cloth. Remove and insert the tubes several
times to clean socket contacts. It may be necessary to
use a pipe cleaner moistened with carbon- tetrachloride.
4. Voltages. The power supply output voltages, — 140,
+225, + 450, — 1500 and +1500 should be checked with
an accurate voltmeter. To check the voltage regulator
circuits, vary the
line
voltage by means of a variable
transformer, and with a voltmeter observe the regulation
limits of the — 140 v., +225 v., and +450 v. supplies.
Compared to their value at a 117 volt line, the output
voltages should be within these limits:
supply -140(4-2-5%) +225 (±2%)+450 (±6%)
105 v. line -0.5% -1% -1%
125 v. line +0.5% +1% +1%
CAUTION — DO NOT EXCEED A LINE
VOLTAGE OF 130.
TROUBLE ANALYZING AND REPAIR
General
It is important that the operation, circuit theory and
physical location of components be thoroughly under ­
stood before repair of the Type 511-A is undertaken. If
the circuit description, schematic diagram and interior
photographs are carefully studied, most defects will be
found relatively easy to locate.
CAUTION — BE SURE TO CHECK THE
SETTING AND ADJUSTMENT OF THE
CONTROLS BEFORE ATTEMPTING RE ­
PAIR, TO VERIFY THAT THE DIFFICULTY
IS ACTUAL.
Although tables of average voltage and resistance
values are included to facilitate servicing, they should
be used for reference only, and are not meant to serve
as a "check list" or sequence chart for circuit testing.
This system might eventually lead to the trouble, but
the
isolation
or signal tracing
methods
are generally
much faster.
Many troubles can be localized by observing the
waveforms at various points in the circuits with the in ­
strument's own cathode ray tube. Another oscilloscope
SECTION 4, PAGE 1 TYPE 511-A, 511-AD