WhitakerAudio J C Whitaker 20 W Stereo Audio Amplifier, Manual

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20 W Stereo Audio Amplifier
the PWB is identified by a square pad. Place the socket in the proper orientation over the
PWB so it rests on the standoffs. The top of the socket (the side the tube plugs into) should
face outward. Loosely tighten the mounting screws. See Figure 5.2 a .
– In a similar manner, mount the tube socket on the rectifier PWB.
– Install connecting wires from the PWB pads to the tube socket pins. Solder in place.
Materials for these steps can be found in the “Tube Socket Hookup” package. Note that
only the active pins need be connected at the socket. The heater connections are made
separately for the amplifier tubes. The recommended procedure for installing the
connecting wires is as follows:
1) Feed a bare wire from the component side through the pad and into the socket
soldering tab.
2) Crimp in place (see Figure 5.2 b ).
3) From the component side, pull the wire tight and solder in place.
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 .)
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.