1-17 Install C16, 470 μF electrolytic, per Step 1-15.
1-18. Install C14, 33 μF electrolytic, per Step 1-15.
1-19. Install C30, 100 μF electrolytic, per Step 1-15.
1-20. Install C11, 1 μF electrolytic, per Step 1-15.
1-21. Install C10, 470 μF electrolytic, per Step 1-15.
1-22. Using a length of bare wire cut from a part already
installed, form a staple-shaped bridge wire and solder it at the
two points joined by the dotted line marked JUMPER near C17.
1-23. Install R17, the 10K volume control potentiometer.
Before soldering, make sure it is seated squarely on the board, to
assure a neat fit to the subpanel.
1-24. Notice that U1, the 9-pin TDA2611A integrated audio
amplifier circuit, has a notch and stripe at one end of the
imprinted side, designating pin 1. Carefully insert U1 into its
position with that notched end in the same direction as the stripe
outlined on the board (i.e., near C17).
1-25. Solder all 9 pins of U1, being sure not to drip excess
solder across any of the pins ("solder bridge.")
1-26. Double check the correctness of parts selection and
parts-orientation in steps 1-1 through 1-25.
At this point, you have installed all parts needed for U1 and Q4
to function as the receiver's audio amplifier. This circuit can be
tested at this time by connecting DC voltage and the speaker.
The value of this test is that you can be assured that the
amplifier circuit indeed is working properly. A potential
disadvantage is that the four hookup wires installed for the test
could become weakened at their solder points from the repeated
handling of the board required by further assembly. Therefore,
the decision to test the amplifier before proceeding depends on
your confidence in the work done so far. lf you do perform the
test, be sure to follow the suggestion in Phase 2 for tucking the
wires out of the way.
Preparation for Optional Audio Amplifier Test:
1-27. NOTE: When we say to "prepare" a length of hookup
wire , this means to CUT the correct length of the specified color
and to STRIP about 1/8" of insulation from each end. To assure
neat wiring of the finished receiver, it is important to cut the wire
lengths as specified. lf any wires are too short, they will
interfere with installing the battery shelf assembly.
1253 - 20
1-28. Prepare a 5.5" length of BLACK wire and solder one
end to the (-) side of “Vcc EXT".
1-29. Prepare a 4.0" length of RED wire and solder one end
to the pad in the "Power Switch" nearest the position for R15.
1-30. Prepare a 5.5" length of WHITE wire and solder one
end to the (+) pad on the "AUDIO OUT" box outlined on the
board.
1-31. Prepare a 5.5" length of BLACK wire and solder one
end to the other (ground) pad in the "AUDIO OUT" box.
1-32. Lightly solder the white (+) and black (-) wires from
"AUDIO OUT" to the(+) and(-) lugs of the 3'' speaker in your
kit. Because this is a temporary connection, you also may use
alligator clip jumper wires. These two wires will be soldered
permanently to the phone jack later.
Phase 1 Optional Progress Test
The purpose of this test is to make sure that the amplifier section
is working property. If it does not, installing more parts will not
fix it!
1-33. DOUBLE-CHECK all preceding assembly steps.
1-34. Connect any 11-14 volt DC voltage source to the red
(+ ) and black (-) wires.
1-35. Turn the volume control all the way up.
At this point you should be hearing a gentle background hiss and
perhaps a soft AC hum. Now, touch one end of R10 with your
finger or a voltmeter test lead: you should hear a strong AC hum.
Rotating the volume control will have the same effect as any
volume control. These are the ONLY sounds you should hear.
There must NOT be any popping, putt-putting or squealing. If
there are ANY such sounds, it means that the amplifier is
oscillating, caused by some error in preceding steps. Make sure
you have the amplifier working properly before proceeding.
1-36. Disconnect the battery or power supply.
1-37. Disconnect the speaker.
1253 - 21
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