Maintenance; Static-Sensitive - Tektronix 2235A Instruction Manual

Section 6
-
2235A Instruction
MAINTENANCE
This section contains information for conducting pre-
procedures are included in the corrective maintenance
ventive maintenance, troubleshooting, and corrective
part of this section.
maintenance on the instrument. Circuit board removal
STATIC-SENSITIVE COMPONENTS
The following precautions are applicable when per-
forming any maintenance involving internal access to
the instrument.
Static discharge can damage any semi-
conductor component in this instrument.
This instrument contains electrical components that are
susceptible to damage from static discharge. Table 6-1
lists the relative susceptibility of various classes of semi-
conductors. Static voltages of 1 kV to 30 kV are common
in unprotected environments.
When performing maintenance, observe the following
precautions to avoid component damage:
1. Minimize handling of static-sensitive components.
2. Transport and 'store static-sensitive components or
assemblies in their original containers or on a metal
rail. Label any package that contains static-
sensitive components or assemblies.
3. Discharge the static voltage from your body by
wearing a grounded antistatic wrist strap while
handling these components. Servicing static-
sensitive components or assemblies should be per-
formed only at a static-free work station by qualified
service personnel.
4. Nothing capable of generating or holding a static
charge should be allowed on the work station
surface.
5. Keep the component leads shorted together when-
ever possible.
6. Pick up components by their bodies, never by their
leads.
7 . Do not slide the components over any surface.
Table 6-1
Relative Susceptibility to
Static-Discharge Damage
a Voltage equivalent for levels (voltage discharged from
a
100-pf capacitor through resistance of 100
a):
Semiconductor Classes
MOS or CMOS microcircuits or
discretes, or linear microcircuits
with MOS inputs (Most Sensi-
tive)
ECL
Schottky signal diodes
schottky T ~ L
High-frequency bipolar
transistors
JFET
Linear microcircuits
Low-power Schottky TTL
TTL (Least Sensitive)
6
=
600 to 800 V
7 =
400 to 1000 V (est)
8
=
900 V
9
=
1200
v
Relative
Susceptlblllty
Levelsa
1
2
3
4
5
6
7
8
9
8. Avoid handling components in areas that have a
floor or work-surface covering capable of gen-
erating a static charge.
9. Use a soldering iron that is connected to earth
ground.
10. Use only approved antistatic, vacuum-type
desoldering tools for component removal.
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