Imsai 8080 - Page 23

IMSAI 8080 System
General Assembly Notes
a joint is to be made immediately. If a tip becomes oxidized,
dipping it in a can of rosin flux is usually sufficient to
enable solder to flow on it again. They may be cleaned of
oxide by fine steel wool or other abrasive, but a plated tip
should never be filed.
The tip of the iron should never have enough solder on it
that it could drip off. If you find that solder tends to
drip off the tip, you are undoubtedly using too much solder.
A solder drip on a P.C. board is often extremely difficult
to see, since it is the same color as the traces, and it is
sure to short several traces and cause trouble or damage
components when the board is operated. Inspect your boards
very carefully for any such solder drips, shorts near soldered
leads, incompletely soldered leads, and unsoldered leads. A
100% inspection of soldering should catch 99% of all problems
before the board is even turned on. When soldering components
with long leads (resistors, etc) we suggest clipping the leads
after soldering so that lead clipping gives you an easy and
positive way to check all the joints on those components. A
completed unit will typically run when first turned on if the
soldering was done correctly.
MOS IC HANDLING
Some of the chips in the kit are MOS type chips (such as
the 8080A, 8111 and 8251). MOS chips are sensitive to
static electricity and other large transient voltages. In
order to prevent damaging these, some precautions should
be followed. They all relate to avoiding the discharge of
static through the pins on one of these chips.
Avoid working in a room with very low humidity. Wearing
cotton fabric or other non-static forming fabrics will
help. Air directly from a heater vent is typically ex
tremely low in humidity and should be avoided in the work
area. Keeping everything involved (chip, board, iron, tools,
boxes, chip containers, work surfaces and you) at the same
potential is required, and the biggest step in achieving
this is continuous physical contact between them. For example,
before removing a chip from a box and setting it on the table,
the box should be set on the table, you should touch the
table, and only then pick up the chip to place it on the table.
Try to handle the chip from the ends rather than the pins as
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