Imsai 8080 - Page 27

IMSAI 8080 System
General Assembly Notes
bent slightly to hold the I.C. in the board while soldering.
Take special care on each and every chip to observe the
following points:
1. That Pin one is in the correct direction. Refer to
marking on the board or assembly instructions to de
termine which direction pin one belongs.
2. After inserting the chip and before soldering, check
that every pin went through the hole properly. Some
times a pin will catch on edge of a hole and bend under
the chip instead of going through. Care should be taken
to avoid this happening and to check before soldering
to make sure it has not happened.
After inserting one or two chips, get a feel for how much
pressure is needed to push it out of the carrier. Any
chips that seem to take more pressure indicate that perhaps
one or more pins are not lined up with the holes properly.
Most chips after insertion, will stay in the. board securely
due to the fact that the leads are normally bent outward
somewhat and will hold the chip by pushing outward against
the holes. Some chips, however, will be loose after inserted.
Extra care should be taken to see that these are properly
against the board when they are soldered. The board can
either be set flat against the table or other surface that
will hold the chips against the board or two diagonally
opposite ends may be bent slightly to prevent the chip from
dropping out.
Power Regulators
The 7805 regulators for the +5 volts are supplied with a
heat sink and mounting hardware. The three leads must be
bent down at the proper lengths to match the solder pads,
and this should be done with the needle-nose pliers. The
lead should come straight out and bend sharply down, rather
than slope gradually towards the hole. After the leads are
bent, the regulator can be fastened to the board along with
the heat sink, using the short 6-32 screw down from the top,
with the lockwasher and nut on the back. The regulator should
be held to prevent turning while the nut is tightened firmly.
The nut should be tight enough to insure good heat conductivity
between the regulator and heat sink and board. Heat sink
grease may be used if desired.
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