Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: David on August 17, 2016, 02:27:41 pm

Title: 5D3 Tweed Deluxe wiring issue.
Post by: David on August 17, 2016, 02:27:41 pm

Hi everybody... I used to be a regular around here but I fell off the planet for a while and lost my other logon info so I am starting over.

I am working on a Tweed Deluxe for a man and I have run up on a question for you guys.

On the 5D3 schematic, it shows one leg of the 6.3 volt secondary tied to the chassis and the other feeding one heater pin on each tube while the other two are jumpered to the chassis.  That is what I am seeing in the amp. So, that makes my mind see the chassis hot at 3.15 VAC and if I install an earth grounded mains cable with the green wire as ground to the chassis, then I will burn up the PT by dumping the filament voltage to earth.

Am I seeing this correctly?

Dave

Title: Re: 5D3 Tweed Deluxe wiring issue.
Post by: sluckey on August 17, 2016, 02:58:44 pm

Quote

Am I seeing this correctly?

No. Fender just used the chassis for the conductor for one side of the filaments. Only needed half as much filament wire. Saved some pennies. Many old amps did the same.

There is no danger connecting the green wire of the power cord to chassis.

Title: Re: 5D3 Tweed Deluxe wiring issue.
Post by: David on August 17, 2016, 03:08:28 pm

Thanks Sluckey,

So just for educational purposes, does that mean that all the filament voltage shifts to one leg of the secondary and the other is at zero volts? Is it because there is no center tap for that secondary?

Dave

Title: Re: 5D3 Tweed Deluxe wiring issue.
Post by: sluckey on August 17, 2016, 03:12:08 pm

Yes, you have 6.3vac across the two green wires coming out of the PT. You can call one of them 6.3 and the one that's connected to the chassis can be called 0.

Title: Re: 5D3 Tweed Deluxe wiring issue.
Post by: David on August 17, 2016, 03:42:11 pm

OK.. Sounds good. Thank you very much.

Dave