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Whew! Well, that's about it for the main circuit board assembly. Take a few
minutes now to double check your work, especially the placement of the po-
larized and orientation specific components. The next time we re-visit this
board we'll be ready to energize the circuit, so this is your last chance to "get
it right the first time" and avoid timely circuit troubleshooting. Remember that
time spent here can save a lot of time (and expense!) when the unit is initially
turned on.
In the final assembly steps for the DF main board, the components will be
mounted to the SOLDER SIDE of the circuit board (aren't you glad you didn't
jump ahead)! This will allow for correct orientation of the controls through the
case assembly. These controls and displays will be the ones you'll be look-
ing at for years to come, so take your time to ensure proper positioning of
each component.
84. Moving to the solder side of the circuit board, identify the locations
for S1 (power), S2 (scan stop), and S3 (phase invert). Carefully insert
the slide switches into position (one at a time is fine) in the S1, S2, and
S3 positions. Ensure that each switch is mounted flush to the circuit
board, and solder into place. The switches are DPDT type, so "up -
down" orientation is not critical. Check the placement of each switch by
"test fitting" the circuit board into the upper half of the case assembly and
observing the switch position. Take care not to "skew" the switch as it
may bind during normal operation.
85. Identify the 10K trimmer potentiometer (labeled 10K or 103 on the
side of the pot). Note that the silkscreen for this part (and R19 and 36) is
on the component side of the PC board. However, this part must be in-
stalled on the solder side of the board. Install this potentiometer from the
solder side of the circuit board in the R50 position. Check the parts
placement diagram for correct placement if you are unsure. Make sure
that this control is mounted flush to the circuit board and solder into
place. Remember that you should be looking at a reverse image of the
circuit board and that R50 is closest to the outside of the circuit board.
86. in the same manner, mount and install the two remaining potenti-
ometers (500K ohms labeled 500K or 505) into the R19 and R36 posi-
tion.
87. Observe the miniature
LED's provided with your kit.
Being diodes, these compo-
nents are polarized and must
be oriented correctly. Examine
one of the LED's and notice
LED
(-)
(+)
DDF1 • 23
Leave these leads
as long as possible
PC Board
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