WhitakerAudio JC Whitaker 20 W Stereo Integrated Audio Amplifier, Manual

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4) Trim the excess lead length.
5) Solder the socket tab.
Table 5.1 shows the pins that should be connected to the PWB.
– Repeat the connection process for each PWB-to-socket connection, being careful to match
up the right pad on the board with the right connection on the socket. (See Figure 5.2 c .)
This is best done by starting at pin 1 on one side of the socket, and on pin 9 on the other
side.
The final step in assembly of the amplifier PWB is to make the heater connections to the three
sockets on the board. The following procedure is recommended.
– Identify pins 4 and 5 on the tube sockets. These pins are used for the heater connections.
– Unscrew and remove the standoff adjacent to pins 4 and 5 on each socket. This will
facilitate access to the pins.
– Open the “Heater Circuit Wire” package; cut one 9-inch piece of #22 green wire and one
9-inch piece of #22 brown wire.
– Place one piece of heat-shrink tubing over one end of each wire.
– Crimp the green wire on pin 4 of V1. Solder in place. When soldering, make sure the heat-
shrink tubing is pushed back on the wire so it is not near the soldering point. If the heat-
shrink tubing gets hot it will be very difficult to slide into position later.
Table 5.1 PWB to Tube Socket Connections
Socket No. V1, 6U8A V2, 6973 V3, 6973 V51, 6CA4
Pin 1 yes yes yes yes
Pin 2 yes no, NC no, NC no, NC
Pin 3 yes yes yes yes
Pin 4 no, heater no, heater no, heater yes
Pin 5 no, heater no, heater no, heater yes
Pin 6 yes yes yes no, NC
Pin 7 yes yes
1
yes
1
yes
Pin 8 yes yes yes no, NC
Pin 9 yes yes yes no, NC
Note 1: On early versions of the PWB, pin #7 was also connected to a ground lug
adjacent to the tube socket via a short (1.5-inch #22) black wire.