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Preventive Maintenance - 212
tors, damaged circuit boards , and heat-damaged parts . The
corrective procedure for most visible defects is apparent;
however, particular care must be taken if heat-damaged
components are found . Overheating usually indicates other
trouble in the instrument ; therefore , it is important that the
cause of the overheating be corrected to prevent recurrence
of the damage .
Semiconductor Checks
Periodically checking the semiconductors in the 212 is
not recommended .
The
best check of semiconductor
performance is actual operation in the instrument . If it is
desired to check the performance of a semiconductor out
of
the
instrument,
a
dynamic
checker
such
as
a
TEKTRONIX Type 576 Transistor Curve Tracer is recom
mended . Lead configurations of the semiconductors used in
the 212 are shown in Fig . 5-2.
An extracting tool should be used to remove the 14-,
and 16-pin flat integrated circuits to prevent damage to the
pins. If an extracting tool is not available when removing
one of these integrated circuits , pull slowly and evenly on
both ends of the device . Try to avoid having one end of the
integrated circuit disengage from the socket before the
other, as the pins may be damaged . When replacing
semiconductors , key the semiconductor's index with that
of its socket . Failure to do so can result in damaged
components.
Recalibration
To assure accurate measurements , check the calibration
of this instrument after each 1000 hours of operation or
every six months if used infrequently . In addition , replace
ment of components may necessitate recalibration of the
affected circuits . The calibration procedure can also be
helpful in localizing certain troubles in the instrument . In
some cases , minor troubles may be revealed or corrected by
recalibration .
3-2
A3 Power Supply Board
A1 Input Board
wwwd o w o d
filt
2000
mu
A2 Amplifier Board
Fig. 3-2. Location of circuit boards within the 212.
A
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