WhitakerAudio JC Whitaker 20 W Stereo Integrated Audio Amplifier, Manual

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20 W Stereo Integrated Audio Amplifier
– 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 last task is to make the heater connections to the three sockets on the PWB. 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 V4. 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.
– Crimp the brown wire on pin 5 of V4. Solder in place, keeping in mind the caution about
the heat-shrink tubing.
Table 5.2 PWB to Tube Socket Connections
Socket No. V4, 6U8A V5, 6973 V6, 6973
Pin 1 yes yes yes
Pin 2 yes no, NC no, NC
Pin 3 yes yes yes
Pin 4 no, heater no, heater no, heater
Pin 5 no, heater no, heater no, heater
Pin 6 yes yes yes
Pin 7 yes yes
1
yes
1
Pin 8 yes yes yes
Pin 9 yes yes yes
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.