Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: nickp on April 29, 2017, 08:00:54 am

Title: Ab763 filter cap grounding photos?
Post by: nickp on April 29, 2017, 08:00:54 am

Im building a one channel ab763 and i like the approach of putting the big electrolytics in the chassis tucked below the pots.

Id love to see some pix of how people have grounded these.  Do you just connect to one of the rails on the board that goes to the PT bolt?

Thanks. 

Title: Re: Ab763 filter cap grounding photos?
Post by: tubenit on April 29, 2017, 08:20:27 am

Excellent info on grounding right here even though it's not an actual photo

http://el34world.com/charts/grounds.htm (http://el34world.com/charts/grounds.htm)

Title: Re: Ab763 filter cap grounding photos?
Post by: nickp on April 29, 2017, 09:57:50 am

Interesting.  Thanks. 

Different than the Layout posted, though, which shows all the big caps grounded at the PT (see page 2 of 5):

http://el34world.com/Hoffman/files/Hoffman_AB763_1.pdf (http://el34world.com/Hoffman/files/Hoffman_AB763_1.pdf)

Title: Re: Ab763 filter cap grounding photos?
Post by: sluckey on April 29, 2017, 10:09:39 am

Here's Hoffman's AB763 project. It shows the caps mounted between the board and pots. Negative end connects to the pot buss on the back of the pots. The plate and screen node caps connect the negative end directly to a PT bolt at the same place the PT center tap connects.

     http://el34world.com/Hoffman/AB763Project.htm (http://el34world.com/Hoffman/AB763Project.htm)

Title: Re: Ab763 filter cap grounding photos?
Post by: nickp on April 29, 2017, 10:30:56 am

Well, I am a giant dum dum (not news to those who know me).  I was looking at those very pictures, and failed to notice the negarive end going to the ground bus. 

Thanks!