5F10A Tweed Harvard Pinouts?

[ellum68]

I'm in the midst of a 5F10 Tweed Harvard build. I'm doing it pretty much stock with the exception of an adjustable bias, standy swith, and using a twisted pair filament wiring setup. I need clarifications on a few things. On the 6V6 pair, pins 2 and 7 are for the heaters, pin 8 goes to the ground, and pin 1 gets skipped? The original layout has pin 1 soldered to for some reason. Next, the 12AX7 has heater hookups at pin 5&9, but pin 4 is skipped. Why is 4 skipped? Last the 6AT6 should use pin 3 and 4 for heaters, right?

http://www.thevintagesound.com/ffg/s...f10_layout.gif

[loudthud]

On the 12AX7 pins 4 and 5 should be connected together. On the 6V6GT you can leave pin 1 unconnected. The old metal 6V6 {nothing} has pin 1 connected to the metal envelope. Fender grounded pin 1 on many old amps as a safety and shielding measure. Pins 3 and 4 are the heater on the 6AT6.

[ellum68]

I was thinking 4&5 on the 12AX7 should be together since they're using the whole tube. Thank you for the confirmation. I haven't been inside in amp since November of '10 when I built my 5F8A. I'll post pics of this thing when it's done (hopefully this evening).

[Bruce / Mission Amps]

I was thinking 4&5 on the 12AX7 should be together since they're using the whole tube. Thank you for the confirmation. I haven't been inside in amp since November of '10 when I built my 5F8A. I'll post pics of this thing when it's done (hopefully this evening).

For what it's worth, I've been finding using a 47K resistor from lug 1 to lug 5 on the 6V6GT sockets and then connecting the phase inverters/driver output to lugs 1 instead... works really good!

[ellum68]

Nothin' like getting a reply from Bruce himself at Mission Amps. lol. I didn't check this in time to try out your suggestion Bruce. I did however kick it on for the first time. As usual, something is amiss. I get a kinda of a squealing sound out of the speaker once I take it off standby. It reminds me a little bit of the sound a loose v-belt makes on an electric motor or car. I double checked all the pot/jack/tube hook ups before I first gave it power. I did pull the 6AT6 with no change (12AX7 is a known good tube). My limited mind is leaning towards my output tranny leads are reversed. Does that sound right?

[ellum68]

Leads flipped, super quiet. Now off to check plate voltages and bias.

[Bruce / Mission Amps]

Leads flipped, super quiet. Now off to check plate voltages and bias.

The bias supply diode on your board is soldered in backwards.... cathode band is supposed to be pointed to the AC voltage source.