SECTION E THEORY OF OPERATION
_____________________________________________________________
E-1.
General
The AMPTEC RESEARCH 620A Fail Safe
Ohmmeter is shown in block diagram form
in Figure E-1. All information disclosed in
this section is proprietary and is included in
order to aid in troubleshooting to component
level possible.
The AMPTEC 620A uses solid-state
semiconductors exclusively and CMOS
circuits extensively to minimize power
requirements and make battery operation
practical.
E-2.
Troubleshooting
Malfunctions are often the result of
misinterpretation of specifications or due to
an incomplete understanding of the
instrument.
A thorough review of the
operating instructions for this instrument
is recommended prior to any component
replacement.
Check to be sure that cables
and other test equipment are in good
working order before attempting to
troubleshoot the 620A. If the 620A exhibits
problems that cannot be eliminated by
reviewing Sections B and D, the following
guidelines have been established to help
solve the problem.
E-2-1. Localizing the Problem
The key to successful troubleshooting is to
localize the problem as much as possible
before trying to pin the problem down to a
specific component. Certain questions
should be asked such as "Does the problem
occur on all ranges or on a specific range
only?". The power supplies are also one of
the first things that should be checked.
Since it is not possible to anticipate all
failure modes of the 620A, servicing
personnel should become familiar with this
section to gain a complete understanding of
the internal workings of the ohmmeter.
E-2-2. Component Replacement
If the problem has been identified as a faulty
component, the accuracy of the 620A can be
maintained only if the following precautions
are taken:
*
Use only the specified component or
its exact equivalent. Spare parts can
be ordered from your nearest
AMPTEC RESEARCH Service
Center or directly from the factory.
Refer to the AMPTEC Components
Parts List Stock Number described in
the
Appendix
Section A pages in the
back of this manual.
*
Use only 63/37 grade rosin core
electronic grade solder with a 50W
or lower maximum power soldering
iron.
*
When soldering, heat the terminal of
the component,
not
the solder.
Apply solder smoothly and evenly.
Do not move the component until the
solder has cooled.
Bad solder joints
can cause more problems!
*
Static sensitive parts require special
handling procedures. Always treat
an unknown part as if it were static
sensitive.
Summary of Contents for 620A SERIES
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