Tektronix 1L20, Инструкция по эксплуатации, Страница: 23 / 117

SECTION 4
MAINTENANCE
Introduction
This section of the manual contains maintenance informa­
tion for use in maintenance and troubleshooting on the
Type 1L20. The early part of the section deals with general
maintenance. This is followed by general information on
corrective maintenance and ordering of replacement parts,
then finally by detailed information on difficult repair and
replacement procedures.
PREVENTIVE M AINTENANCE
General
Preventive maintance consists o f cleaning, visual inspec­
tion, lubrication, and if needed, recalibration. Preventive
maintenance is generally more economical than corrective
maintenance, since preventive maintenance can usually be
done during idle periods at a time convenient to the user.
The preventive maintenance schedule established for the
instrument should be based on the amount of use and on the
environment in which the instrument is used.
Cleaning
The Type 1L20 should be cleaned as often as operating
conditions require. Accumulation o f dirt in the instrument
can cause overheating and component breakdown. Dirt on
components acts as an insulating blanket and prevents effici­
ent heat dissipation. It also provides an electrical leakage
path.
CAUTION
Avoid the use of chemical cleaning agents which
might damage the plastics used in this instrument.
Some chemicals to avoid are benzene, toluene,
xylene, acetone or similar solvents.
Exterior
Loose dust accumulated on the front panel o f the instru­
ment can be removed with a soft cloth or small paint brush.
The paint brush is particularly useful for dislodging dirt and
dust around the front-panel controls. Dirt which remains can
be removed with a soft cloth dampened in a mild solution of
water and detergent. Abrasive cleaners should not be used.
Interior
Due to its electrical conductivity under high-humidity condi­
tions, dust in the interior of the instrument should be removed
occasionally. The best way to clean the interior is to blow
o ff the accumulated dust with dry, low-velocity air. (High-
velocity air can damage some components.) Remove any dirt
which remains with a soft paint brush or a cloth dampened
with a mild detergent and water solution. A cotton-tipped
applicator is useful for cleaning in narrow spaces or for
cleaning ceramic terminal strips.
Lubrication
The life o f the rotary switches w ill be lengthened if these
devices are kept properly lubricated. Use a cleaning type
lubricant (such as Cramoline) on shaft bushings, plug-in con­
nector contacts, and switch contacts. Lubricate the switch
detents with a heavier grease (Beacon No. 325 or equiva­
lent). The necessary materials and instructions for proper
lubrication of Tektronix instruments are contained in a com­
ponent lubrication kit which may be ordered from Tektronix.
Order Tektronix Part No. 003-0342-00.
Visual Inspection
The Type 1L20 should be inspected occasionally for such
defects as broken connections, broken or damaged ceramic
strips, improperly seated vacuum tubes or transistors, and
heat-damaged parts. Care must be taken if heat-damaged
parts are located. Overheating is usually a symptom of
other troubles. For this reason, it is essential to determine
the actual cause of the trouble; otherwise the damage may
be repeated.
Tube and Transistor Checks. Periodic preventive mainte­
nance checks consisting only of removing the tubes and
transistors from the instrument and testing them in a tester
are not recommended. The circuits within the instrument
provide the only satisfactory means of checking tube and
transistor performance. Defective tubes or transistors w ill
usually be detected during recalibration of the instrument.
Details o f in-circuit tube and transistor checks are given in
the troubleshooting procedure later in this section.
Performance Checks and Recalibration
To insure accurate measurements, the instrument preform-
ance should be checked after each 500 hours of operation
or every six months if the instrument is used intermittently.
The calibration procedure is helpful in isolating major trou­
bles in the instrument. Moreover, minor troubles not apparent
during regular operation are frequently revealed and cor­
rected during recalibration. Performance Check instructions
are given in Section 5; Calibration instructions are given in
Section 6.
CORRECTIVE MAINTENANCE
General
Corrective Maintenance consists o f component replacement
and instrument repair.
NOTE
If the dial error on Band 1 or Band 2 exceeds
± 2
M H z + 1 % o f the dial reading, the instrument
should be returned to the factory for repair a n d /
or calibration. Local Oscilllator and dial tape c a li­
bration procedures have been included at the end
of Section 6, but should be used only if the instru­
ment cannot be returned to the factory. Because
of the interaction between the adjustments, it w ill
usually be more satisfactory (and more economi­
cal) to have the Local Oscillator recalibrated by
our factory technicians.
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