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Preventive Maintenance
Preventive maintenance consists of cleaning, visual inspec
tion, lubrication, and if needed, recalibration.
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 the
environment in which the instrument is used.
Cleaning. Clean the instrument often enough to prevent
accumulation of dirt.
Dirt on the components acts as an
insulating blanket (preventing efficient heat dissipation) and
may provide conducting paths.
Clean the instrument by loosening the accumulated dust
with a dry, soft paint brush. Remove the loosened dust by
vacuum and/or dry, low pressure compressed air (high
velocity air can damage certain components).
dirt and grease may be removed with a cotton-tipped swab
or a soft cloth dampened with water and a mild detergent
solution (such as Kelite or
pray White). Abrasive cleaners
should not be used.
CAUTION
Do not permit water to get inside controls or shaft
bushings.
Lubrication. The life of potentiometers and rotary switches
is lengthened if these devices are kept properly lubricated.
Use a cleaning type lubricant (such as Cramoline) on shaft
bushings and switch contacts.
with a heavier grease (Beacon grease No. 325 or equiva
lent).
Do not over-lubricate.
instructions for proper lubrication of Tektronix instruments are
contained in a component lubrication kit which may be
ordered from Tektronix. Order Tektronix Part No. 003-342.
Visual nspection. After cleaning, the instrument should
be carefully inspected for such defects as poor connections,
damaged parts, and improperly seated transistors. The rem
edy for most visible defects is obvious; however, if heat
damaged parts are discovered, determine the cause of
overheating before the damaged parts are replaced. Other
wise, the damage may be repeated.
Transistor
Checks.
Periodic
checks consisting only of removing the transistors from the
instrument and testing them in a tester are not recommend
ed.
The circuits within the instrument provide the most
satisfactory means of checking transistor performance. Per
formance of the circuits is thoroughly checked during cali
bration so that substandard transistors will be detected at
this time. Check suspect transistors by substitution. Be sure
the substituted transistor is the same type as the one re
placed, and that the substitute itself is good. If the original
transistor is found to be good, return it to the same socket
from which removed.
SECTION 4
MAINTENANCE AND
CALIBRATION
Preventive
Hardened
Lubricate the switch detents
The necessary materials and
preventive
maintenance
Recalibration. Instrument accuracy is ensured if the cali
bration of the Type 114 is checked after every 500 hours
of operation (every six months if the instrument is used inter
mittently). Complete recalibration instructions are contained
later in this section.
The calibration procedure is helpful in isolating major
troubles in the instrument.
apparent during regular operation may be revealed and
corrected during recalibration.
Corrective Maintenance
General Troubleshooting.
erating, attempt to isolate the trouble by a quick opera
tional and visual check.
Make sure that any apparent
trouble is actually due to a malfunction within the Type
114 and not due to improper control settings or a fault in
associated equipment.
Operate the front-panel controls to see what effect, if
any, they have on the trouble symptoms. The normal or
abnormal operation of each particular control helps in
establishing the nature of the trouble. The normal function
of each control is listed in
If the trouble cannot be located by means of front-panel
checks, remove the instrument from its case and check volt
ages and waveforms against those shown on the schematics
in
ection 5, starting with the power supply connections.
Once the trouble is isolated to a particular circuit, refer to
the circuit description in
ection 3 for an explanation of
how the circuit normally operates.
CAUTION
Be careful when making measurements on live
circuits. The small size and high density of com
ponents used in this instrument result in close spac
ing. An inadvertent movement of the test probes,
or the use of oversized probes, may short between
circuits.
Helpful Hints:
1. Check the voltage between chassis ground and the
top end of R244 (333 Ω 10 watt resistor mounted at the
top-right-rear of the chassis).
the voltage at the top of R244 should read 31 to 35 volts
if the AMPLITUDE switch is set to + ; 6 to 10 volts if the
switch is set to — .
2.
et the AMPLITUDE switch to + and turn off the power.
Using an ohmmeter, check the resistance from the top end
of R244 to chassis ground.
filter capacitors, the resistance reading should be about
800 Ω to 2 k.
If it is not, reverse the meter leads and re
check.
Moreover, minor troubles not
If the instrument is not op
ection 2 of this manual.
With normal line voltage,
If there is no charge on the
4-1
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