ELECRAFT 23
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The ICs to be installed in the next step are very
sensitive to static discharge. Touch a grounded surface
before handling each IC. Also note that U4's label will read
upside-down (pin 1 at the right) when properly installed.
Install the following ICs. Before soldering, verify that the ICs
are oriented correctly (pin 1 associated with a round or oval pad).
__ U4, A6B595KA or TPIC6B595
__ U3, A6B595KA or TPIC6B595
__ U2, 74HC165
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The bargraph LED will be installed in the following two
steps. This component must be seated flat on the PC board or it
will interfere with final front panel assembly. Also, any
misalignment will be visible from the front of the K2.
Locate the bargraph LED, DS2. The bargraph has a beveled
corner or edge that indicates pin 1. Install DS2 as shown by its PC
board outline, just to the left of the LCD. Bend two opposite corner
pins slightly to hold it to the board, then solder only these two
pins.
If the bargraph is not perfectly flat against the PC board, re-
heat the solder on the corner pins alternately while pressing it
down. Once it is in the correct position, solder the remaining pins.
Remove any hardware supplied with the microphone jack, J2.
The nut and washer will not be used.
Install the microphone jack (J2) in the lower left-hand corner
of the board, with its polarizing nub at the top (Figure 5-4). Press
the jack down until it is completely flat against the PC board. Re-
check the orientation of the polarizing nub before soldering.
Polarizing
nub
Figure 5-4
Install two 3/16" (4.8 mm) diameter x 1/4" (6.4 mm) long
round standoffs on the top of the board, adjacent to the
microphone jack (Figure 5-5). Use two #4 lock washers between
each standoff and the PC board as shown. Secure the standoffs from
the bottom side with chassis screws. Recall that "chassis screw" is
short-hand for 3/16" (4.8 mm) long pan-head machine screws.
Figure 5-5
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