Power Transformer Question for a Champ build

[Resonator Guy]

I recently purchased a power transformer for a Champ build and it has an extra pair of secondaries. Two are 660 V which is what I wanted and the other two are 600V. Can I just tape the 600 pair off and ignore them?
Also it has a green/yellow with the 6.3 V pair which I figure is a ground. Correct?

Thanks!

[eschertron]

Does the vendor supply that info? When you say 'extra pair' do you mean another winding, separate from the 660v secondary or do you mean 600v taps on a single wind? If they are taps, then go ahead and tape them off.
Also, you are most likely correct about the green/yellow wire. The other heater wires are solid green?
Use your meter to Ohm out the windings, and you will be able to answer your questions from direct observation.

[Resonator Guy]

They are taps on a single wind, according to the picture with the specs. The other 6.3V wires are indeed green.

[g1]

Yes you can tape off the 600V taps, and be sure to secure them so they can't move around.
The green/yellow is the centre tap for the heater winding. You can use it, or tape it off and use resistors for "virtual" centre tap.

[loudthud]

Some of the old Fender layouts show one side of the 6.3VAC winding grounded. That was a cost cutting measure that Fender did on lower cost amps, these days nobody would do that on any audio circuit. Today we run the extra wire to each tube and ground the center tap, that's the green wire with the yellow stripe. If you ground two wires from the same winding, that would be a short which would blow a fuse or damage the transformer. For lower hum, twist the green wires together as they go from tube to tube.

The extra 600V wires can be left unconnected, but they need to be insulated. Don't use electrical tape, it will come off in a few years. Even heat-shrink tubing can come off in time. The best thing to do is solder the wires to unused pins of the rectifier tube socket, a terminal strip or unused eyelets. If you have to use heat-shrink, clip any exposed wire off or bend it back along the insulation to create a bump so the heat shrink can't slip off. Use an extra long piece of heat-shrink and maybe a tie-wrap to prevent any possibility that the insulation will come off in time.

[Resonator Guy]

Okay, I mis-spoke in my initial post. The last build I did was with a new Hammond transformer and I will stick with them from now on. It only had two green wires for the 6.3 V heaters. One was grounded. Now these Chinese transformers have two green and one green/yellow. One of the greens get grounded. Where precisely does the green/yellow go? I regularly use the wiring diagrams in Dave Funk's book and can see no mention of the green/yellow.
I will follow your suggestion on the 600 V taps. I have seen tape and heat-shrink come off. The sockets used on this amp have lots of extra ground tabs so that should be easy.
But I don't understand the centre-tap, so some assistance would be appreciated.
I am working on an early Carvin amp that I mentioned in this thread http://music-electronics-forum.com/t34447/ .I since discovered that the PT was shot when I went to re-test something and one lead blew right off the fuse. Someone had put a 6amp fuse in there and I neglected to check it. So now I am installing a vertical mount Champ transformer, converting the 6X5 to a 5Y3 and using a 6SL7 and a 6V6.
It will look almost stock and sound pretty good I hope.
The centre tap will come into play on my next build after this as I have a similar PT purchased for this other build. I will be giving this one a go later in the winter. http://music-electronics-forum.com/t34379/

[madkatb]

If you're using cathode, rather than fixed, bias for the 6v6 then attach the green/yellow to pin 8 at the 6V6 tube base. That will offset the AC heater wiring by how ever much DC you have on the cathode and help eliminate heater hum.

[Bruce / Mission Amps]

It sounds like you want to wire the filament string wired up the old 50"s way... that is the inferior way.
However, if yes, ...then use one green wire to the sockets and ground one green wire.
Ground one of the filament lugs of the 6V6 socket and probably lug 9 of the 12AX7 socket.

As for the unused wires from the transformer, clip them to about 2" long, fold back about 3/8" of the wire and squeeze it real tight like a flat J, then slip a 3/4" long piece of shrink tubing over the folded end so only the rounded "J" part shows and the other end of the shrink tubing slips well past the open end of the lead wire.
When it shrinks up ... there is no way it can ever slip off....

oops just noticed you are using a 6SL7 preamp tube..... that only has two lugs for the 6vac string so just pick one to ground and the other for the left over filament wire from the 6V6 socket....

[Resonator Guy]

Thanks madkatb, eschertron, g-one, loudthud
and Bruce. That should do the trick. I won't start all this yet, and I will likely be back later for more help.

[eschertron]

It sounds like you want to wire the filament string wired up the old 50"s way... that is the inferior way.
However, if yes, ...then use one green wire to the sockets and ground one green wire.
Ground one of the filament lugs of the 6V6 socket and probably lug 9 of the 12AX7 socket.

As for the unused wires from the transformer

... including the green/yellow wire if you are doing the filaments like above!!