Maintenance; Static-Sensitive Components; Susceptibility To Static Discharge Damage - Tektronix 2445A Service Manual

Section 6-2445A/2455A Service
MAINTENANCE
This section of the manual contains information for conducting preventive maintenance, troubleshooting, and corrective
maintenance on the instruments.
ST A TIC-SENSITIVE COMPONENTS
The following precautions are applicable when perform-
ing any maintenance involving internal access to the
instrument.
~
Static discharge can damage any semiconductor
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
semiconductors. Static voltages of 1 kV to 30 kV are com-
mon in unprotected environments.
When performing maintenance, observe the following
precautions to avoid component damage:
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
performed 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
whenever possible.
6. Pick up components by their bodies, never by
their leads.
Table 6-1
Susceptibility to Static Discharge Damage
Relative
Susceptibility
Semiconductor Classes
Levels•
MOS or CMOS microcircuits or discretes,
1
or linear microcircuits with MOS inputs.
(Most Sensitive)
ECL 2
Schottky signal diodes 3
Schottky TTL 4
High-frequency bipolar transistors 5
JFETs
6
Linear microcircuits
7
Low-power Schottky TTL 8
TTL (Least Sensitive) 9
•Voltage equivalent for levela: (Voltage diacharged from a
100 pF capacitor through a resistance of 100
O).
1
=
100 to 500 V
2
=
200to500V
3
=
250V
4
=
500 V 7
=
400 to 1000 V (est.)
5=400to600V 8=900V
8
=
800 to 800 V 9
=
1200 V
7. Do not slide the components over any surface.
8. Avoid handling components in areas that have a
floor or work-surface covering capable of gen-
erating a static charge.
6-1