Table of Contents
Advertisement
PREVENTIVE MAINTENANCE
Preventive maintenance, when performed on a regular
basis, can prevent instrument breakdown and may improve
the reliability of the 221. The severity of environment to
which this instrument is subjected w ill determine the
frequency of maintenance. A convenient time to perform
preventive maintenance is preceding recalibration of the
instrument.
Disassembly
To gain access to the interior of the instrument, unwind
the probe and the power cord from the rear of the
instrument. Remove the five screws in the bottom cover of
the instrument. See Fig. 3-1. Gently separate the bottom
cover from the instrument and lay aside.
If access to the fro n t of the Input circuit board is
necessary, remove the knobs from all of the external
control shafts. Remove the two screws securing the side
panel to the Input circuit board and remove the instrument
side panel.
Cleaning
The 221
should be cleaned as often as operating
conditions require. Accumulation of d irt in the instrument
can cause component breakdown.
The high impact plastic covers provide protection against
dust in the interior of the instrument. Loose dust accu
mulated on these covers can be removed w ith a soft cloth
or small brush. The brush is also useful for dislodging d irt
on and around the side panel controls. D irt that remains
can be removed w ith a soft cloth dampened in a mild
detergent and water solution. Abrasive cleaners should not
be used.
Cleaning the interior should only be occasionally neces
sary. The best way to clean the interior is to blow o ff the
dust with a dry, low-velocity stream of air. A soft-bristle
brush or a cotton-tipped applicator is useful for cleaning in
narrow spaces or for cleaning more delicate components.
Avoid the use o f chemical cleaning agents which
m ight damage the plastics used in this instrument.
Avoid chemicals which contain hydrochloric acid,
sodium hydroxide, or sulfuric acid.
REV. APR 1974
Section 3 —221 Service
3-1
Advertisement
Chapters
Table of Contents
