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Install the transistors. Spread the outside leads a bit to make it easier to insert them into
the board.
Orient the transistor so its body shape matches the silk-screen outline. Leave the
top of the transistor about ½" off the board! The lead length prevents stress on the
body and keeps the transistor safe from too much heat during the soldering
operation.
Designation
Value
Q1
2N5551, NPN
Q2
2N5551, NPN
Q3
2N5551, NPN
Now install the speaker coupling capacitor:
Watch the polarity! Make sure the minus sign faces away from the plus sign on the
silk screen. That puts the minus side of the cap along the outer edge of the circuit
board.
Designation
Value
C7
3300 uF 63V
The speaker coupling capacitor will either snap or push into place. Verify once more that
you have polarity correct, and then solder both speaker terminals to the circuit board.
This will probably take more heat, time, and solder than anything you have soldered up to
now.
Winding the Output Inductor
This step takes just a bit of finesse, but if you've come this far, you have nothing to worry
about. If you're a bit frazzled, take a break before proceeding.
There...feel better? OK, let's go. Just follow these steps:
1. Cut a 21" length of solid wire. A great place to get it is from the output inductors
wound around the old Dynaco output capacitors (see Figure 10).
2. Strip back 0.5" of insulation from one end of the wire.
3. From the component side, place the stripped end of the wire into the L1A
terminal. Route it around the output capacitor as shown in Figure 11.
4. Solder the wire on the component side into the L1A hole.
5. Wind 5 turns of wire, close spaced, so it looks like Figure 11. When you get to the
end of the coil, carefully estimate the amount of wire you'll need to make it from
the top of the coil down through the L1B hole in the board. You can make this
step a bit easier if you strip back a bit more insulation than you think you'll need.
6. Pull the end of the wire through the L1B hole, and solder it on the back of the
board.
Marking
2N5551
2N5551
2N5551
Marking
3300 uF, 63 WVDC
Page 20 of 32
Done?
Done?
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