HAMPTONe6. INTEGRATING THE PSU AND AUDIO
Or NEXT STEP
1. Strip/tin the 13" 22 gauge black wire, and the 13" 22 gauge green wire, and tightly twist them into a pair. Unbolt the psu board from the bottom chassis. Attach the green/black pair, and the point-point wires for channel 2 power to the psu pcb according to the schematic. Mount the psu board permanently with all 4 x 1/4" #4-40 panhead screws.
2. Install the two grommets into the two holes in the center divider, and install the divider with the flanges facing the power supply using 3 x #4-40 ¼" flathead screws (the hole off to one side is on the same side as the optional rear panels connections. If you wire parallel audio connections to the back, you will use this hole. Leave the divider a little loose for now).
3. Pass all the point-point wires through the center hole in the divider. Wire the channel power wires to the channels according to the schematic first, then the black/green pair to the pilot.
4. Double check all point-point wiring, this part of the assembly is where most problems occur. Make certain all the point-point wires are clipped off so they cannot make contact with the chassis once the boards are mounted to the chassis.
5. ADD PICTURE Bolt the front panel in place from the bottom with 3 x #4-40 1/4 flathead screws from the bottom. The circuit boards press onto 4 press fit standoffs in the front. Tighten the front panel. Bolt the audio channel pcb’s to the chassis with the 6 (3 per channel) ¼" philips panhead screws.
6. ADD PICTURE Install the tubes into both channels, one 6072A and one 12AU7A per channel. Looking at the preamp from the front, the 6072As go into the left tube sockets of each channel (the ones closest to the input transformers), the 12AU7As go next to the output transformers. If you reverse them the circuit will have about 10dB less gain and will be improperly biased, but no damage will occur since the two tubes are both dual triodes, and are pin-pin compatible.