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Turrets are seated into the board using this
special attachment |
With
the completion of the drilled and polished G10 board, the next
step is the installation of the turrets. As you will recall, a
turret is placed into a hole in the board. A special tool is put
on the drill press and this is pressed into the turret in the
board. As the
drill press turns this attachment, an expansion of the base of
the turret inside the board creates the gripping pressure to
assure the turret is sturdily secured.
This time-consuming process
is continued until all of the turrets have been installed in
the G10 board. Take
a look at the top left corner of the completed turret board
and you will see an angled cutout. Mikey did this to
allow space for proper clearance of the CTS 10K bias pot that
will be installed into the bottom of the chassis directly
below this area.

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The
finished G10 board with all of the turrets securely in
place |

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The
power rail (red) and ground rail (black) buss wires are
soldered to the turrets |
With
the turrets in place, the power rails and ground rails are
installed. Mikey has come up with an innovative way of
doing this instead of using the typical, un-insulated buss
wire. The red and black wires in the picture look like
separate pieces of Teflon stranded wire but they are
not. Instead,
he takes a single length of 18-gauge buss wire (the same kind
soldered to the back of the pots) and runs one continuous
piece to the power rail turrets and to the ground rail
turrets.

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Power
rail (red) wrapped around
turret |
Just
before soldering these in place, Mikey removes the Teflon
insulation from some 18-gauge stranded wire, cuts it to size
and slides the Teflon shielding over the 18-gauge solid buss
wire. In this close-up, you can see the how the
continuous buss wire, wrapped in Teflon shield is wrapped
around the turret and soldered. Also notice some of the
turrets are wired together with thinner buss wire than what is
used for the power and ground rails.
Having
the turrets wired together performs the same function as
hooking up two components to the same terminal, which will be
done in a few places in this amp. It’s really the choice
of the amp designer. Doing it this way keeps the
components lined up nicely but it requires additional labor to
install the extra turrets.
From
this point, there is a fair amount of work that goes into
putting the hookup wiring into the rest of the board. In order to minimize
noise, Mikey runs the signal wires under the board, surfacing
them right at their connection points. In the next photo, you
can see the DRRI chassis with the pots and transformers
installed, awaiting the completion of the main board.

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DRRI
chassis (top) and main board with all hookup wires
(below) |

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Capacitors and resistors in the Normal channel of
the amplifier |
With
the hookup wires in place, the next step is the installation
of the components, primarily capacitors and resistors.
In an earlier section I discussed the construction of
capacitors. Remember, the function of capacitors is to
restrict DC current and shape tone.
The
function of a resistor, as the name implies, is to provide a
specific amount of opposition to current flowing through
it. This causes a voltage drop, which the resistor does
by radiating heat. This lets you control how much
voltage you want to work with in various parts of the
circuit. Resistors have a power rating that tells how
much
power/wattage
(volts x current) they are capable of
handling.
In
the stock DRRI, some1/4-watt resistors are used, which Mikey
feels are undersized.
He
uses 1-watt resistors throughout his circuits with the
exception of a few 1/2-watt metal and carbon film resistors in
non-critical sections. Of interest, the pots used to control the amp are just
variable resistors. You can identify resistors very
easily in the photos since they have bands of color, which are
used to show the rating of the resistor measured in
ohms. The rest of the components soldered to the turrets
are capacitors, which come in a wide variety of colors, shapes
and sizes.

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| Capacitors and resistors in the "Vibrato" /
Tremolo channel |
This
next photo is of the “Vibrato” channel. For those of you that
might not know, Fender created a lot of confusion by naming
the second channels of their amps “Vibrato”, which is the
modulation of pitch (like what a whammy bar on a guitar
does). In fact,
it is Tremolo, not Vibrato, which is produced by this part of
the circuit.
Tremolo modulates volume, not pitch. Fender knows
better but they continue to use the word Vibrato on their amps
so I have chosen to refer to this channel as Vibrato during
this article because that is what it says on the faceplate of
the DRRI.

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Close-up of capacitors (red), resistors (color
banding) and wiring |
As
I examined the pictures Mikey was sending me of the building
of the board, I could see the red wires were connected to the
red power rail and the green wires were connected to the black
ground rail. I
assumed the white wires were signal wires (carrying the guitar
signal) but I wasn’t sure about the blue wires so I asked
Mikey. Here’s
what he said:
“The
red wires do go to the power rail and the plates of the preamp
tubes. The greens
do go to ground and go to the cathodes on the preamp
tubes. The white
wires are signal wires.
On the bottom side of the board, they go to the grids
of the preamp tubes and on top, they'll go to the pots. The blue wires run
from the phase inverter to the power tubes so they're like
signal wires. I just use blue to differentiate those, plus, I
like blue!”

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Fully
completed main board with all components and hookup
wires in place |

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Left
side of completed main
board |

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Right
side of completed main
board |
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