WhitakerAudio J C Whitaker 20 W Stereo Audio Amplifier, Manual

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20 W Stereo Audio Amplifier
– Using the available tie-wraps, organize the wiring between the rectifier PWB and the left
channel PWB, and between the rectifier PWB and the right channel PWB.
– Examine SW203, the over-temperature sensor. Aside from the vacuum tubes, the
component that generates the most heat is the power transformer. SW203 will therefore be
mounted adjacent to power transformer T51. Loosen the rear-facing mounting screw on
T51 adjacent to relay RLY51. Do not remove the nut. Slide the open mounting tab of
SW203 under the nut and tighten. Position the free end of the mounting tab under the
transformer lead grommet. When tightening the nut, be careful to not crimp the wires that
run alongside the mounting screw.
– Prepare two 18-inch long #22 white wires. Attach quick disconnect terminals to one end
of each wire. Connect the free ends of the wires to the temperature sensor, SW203. If
desired, short pieces of heat-shrink tubing may be placed over the connection points.
Solder. Twist the wires together. Route toward the power management expansion PWB
using the available rear cable clamp. Attach quick-disconnect terminals to the free ends of
the wires. They will be connected later.
If desired, a single light coat of brush-applied acrylic conformal coating (MG Chemicals
#419C-55ML) may be applied the temperature sensor terminals.
– Prepare a 14-inch long #22 black wire. Attach a quick-disconnect terminal to one end of
the wire. Attach to the GND post in the center of the power management PWB. The other
end of the wire will be connected later.
– Prepare a 17-inch long #18 stranded white wire. Attach quick-disconnect terminals to each
end of the wire. Connect one end to the neutral load terminal of filter FL51. Use a pair of
long-nose pliers to make the connection. Connect the other end of the wire to the
ACneutral post on the power management PWB. Route the wire through the nearby cable
clamp.
– Prepare a 18-inch long #18 stranded white wire. Attach quick-disconnect terminals to each
end of the wire. Connect between the N-1 post on the right channel PWB and the LoadN
post on the power management PWB. Route the wire through the nearby cable clamp.