INFICON TM-400 Thin Film Deposition Monitor - Manual (Page 77)

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TM-350/400 Operating Manual
Chapter 11
Repair and Maintenance
11.1 Handling Precautions
Integrated Circuits (I.C.’s) can be damaged by static discharge into their inputs.
This static discharge is the same phenomenon that produces the unpleasant shock
when one grabs a doorknob after walking across a carpet. The likelihood of static
buildup is proportional to the dryness of the air and can be particularly troublesome
in cold, dry climates, or hot desert climates.
In order to minimize the chance of discharging body charge into the I.C. inputs,
always handle circuit boards by the edge, avoiding contact with the connector area.
When moving a board from one surface or work area to another surface or work
area, always personally touch the new surface or location before laying down or
inserting the board so that you, the board, and the surface, or equipment, are all at
the same potential. It is wise in dry climates to minimize the amount of movement
when handling or replacing I.C.’s in circuit boards. When handing a circuit board or
I.C. to another person, always touch the person first.
Wood or paper surfaces are the most forgiving surfaces to work on. Plastic should
be avoided. Metal is O.K. as long as the metal is always touched with the hand prior
to laying down the I.C.’s or circuit boards.
P.C. boards or I.C.’s should never be placed in plastic bags unless they are of the
conductive plastic type intended for this use. These bags are typically black or pink
and are normally labeled as conductive or anti-static. If no conductive plastic bags
are available, boards or I.C.’s can be wrapped in paper, and then placed in plastic
bags or shipping bags.
If the above precautions are observed, the chance of damage will be minimal and
no problems should be encountered.
11.2 Maintenance Philosophy
The TM-350/400 was designed around a maintenance philosophy of board
replacement. Field repair at the component level is not recommended and indeed
can void the warranty. The following sections are intended primarily as an aid in
understanding the operation of the TM-350/400 and to help in isolating problems
to the board level.
All electronic components, with the exception of the power supply transformer, are
mounted on plug-in assemblies for ease of removal and replacement. The circuitry
is partitioned among plug-in modules on a functional basis to make fault isolation
to the plug-in assembly level as straightforward as possible.
Most problems can be diagnosed to the board level without external test equipment
and verified by simple board replacement.