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Figure 6-5 Distributor and Pump Gear Case Removal
6.2 Precautions for
Servicing CMOS
Circuitry
Ground Strap
Ground Straps
Most of the circuitry in the 3700 Portable Samplers is made up of
CMOS components. Because of the oxide gate structure of these
devices, they are extremely susceptible to destruction caused by
the discharge of static electricity through their inputs. Because of
this risk, you must take certain precautions when working on
these circuits.
Hazard of Static Electricity. The voltage levels present from
static buildup from walking over carpeted floors, movement of
woolen or synthetic clothes over chair seats, workbenches,
etc., are high enough to destroy CMOS circuitry when you are
performing repair work.
Ideally, all tools, soldering irons, etc., should be grounded, and
you should conduct all work on a grounded metal workbench,
with a grounding strap worn around your wrist. Obviously, in
field repair situations, such precautions are impractical.
However, you must avoid certain extreme hazards.
1. Never perform any work in a room with a carpeted floor.
2. Always roll up the sleeves of work clothes so that your
arms are in contact with the working surface.
3. Avoid using a work surface made of an extremely good
insulator. Avoid laminated counter tops and glass, which
are good insulators. A metal surface is best; a wood surface
3700 Portable Samplers
Section 6 Servicing
CAUTION
Unscrew the
four screws
and the
ground straps
to remove the
distributor
gear case.
6-7
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