Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: NoDough on March 12, 2022, 12:12:42 pm

Title: Help w/ Mercury Transformer Wiring for 5F2A Build
Post by: NoDough on March 12, 2022, 12:12:42 pm

Hello electron wizards! So I need a little bit of help with figuring out my wiring on a new 5F2A build.

I am building a Weber 5F2A, here is the layout and schematic.

Layout
(https://i.imgur.com/PjypTTL.jpg) (https://i.imgur.com/PjypTTL.jpg)

Schematic
(https://i.imgur.com/ZXuiFIG.jpg) (https://i.imgur.com/ZXuiFIG.jpg)

I'm running into a little bit of trouble in trying to figure out the wiring of the Mercury Magnetic transformers I have as replacements. Here are the spec sheets for the transformers:

Power Transformer
(https://i.imgur.com/bBlCu5D.jpg) (https://i.imgur.com/bBlCu5D.jpg)

Input Transformer
(https://i.imgur.com/IvVrbL0.jpg) (https://i.imgur.com/IvVrbL0.jpg)

So let's start with the Power Transformer. I have 2 questions here.

1) So which black lead on the Mercury transformer should go to the AC switch? An electronics guru friend of mine told me although the black leads are somewhat interchangeable, the phase of the AC coming in can effect the noise floor. So I would like to wire these up correctly. My guess is the 0V lead will go to the AC switch, but hopefully you can help answer this.

2) What should I do with the Red/White bias lead? Again I assume here that I will just wrap it with electrical tape, put some heat shrink on it, and tuck it away from everything, but I want to double check here first.

Now, onto the output transformer. 2 questions again here:

1) Black or Red for Power? I have assumptions here as well as I believe the black lead will be used for power, while the red lead will be used for the signal, but some guidance would be helpful. This would mean the black lead corresponds to the brown lead from the original transformer, and the red lead would corresponds with the blue lead from the original transformer.

2) What to do about the Self Lead? So the self lead is grounded to the chassis of the transformer, so luckily I don't need to make another connection here, however the original layout calls for it to be grounded through the speaker jack. My assumption here is I just need to ground the speaker jack and call it a day.

Thanks in advance for any help and insight you can offer.

Title: Re: Help w/ Mercury Transformer Wiring for 5F2A Build
Post by: sluckey on March 12, 2022, 12:51:15 pm

PT
     1) It doesn't matter.
     2) That's correct.

OT
     1) Connect the black lead to the tube pin 3. If amp squeals, reverse the black and red leads.
     2) Your assumption is correct.

Title: Re: Help w/ Mercury Transformer Wiring for 5F2A Build
Post by: NoDough on April 08, 2022, 02:57:15 am

Update: Just in case anyone finds this thread in the future and has the same question. I ended up switching the wiring from I had previously mentioned on the output transformer. The black wire is going to the tube (receiving the guitar signal), and the red wire is going to the eyelet board to receive the all important B+.

Thanks sluckey for your help with all of these questions. This is the second amp build that has benefited from your seemingly infinite wisdom. Thanks for all that you do in this community  :worthy1: