Grounding layout for Hoffman Stout.

[Oddvar]

Hi.  I am a bit uncertain on what to ground on a Hoffman 18w stout.  Can anyone enlighten me?

[tubenit]

Hoffman's Library of Information.

http://el34world.com/schematics.htm#Hoffman_Stout

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

[Oddvar]

 The pots seem to have 3 groundings, I am a bit uncertain about where the filter cap grounding from the pot would be on the Stout?   

I suppose the CT of the heaters go there to? Then I won't need the 100rs from the pilot lamp?

[sluckey]

The pots seem to have 3 groundings, I am a bit uncertain about where the filter cap grounding from the pot would be on the Stout?   

I suppose the CT of the heaters go there to? Then I won't need the 100rs from the pilot lamp?

There are only two ground points in the Stout. One is called the "Ground Buss". The ground buss is just a stiff length of wire that runs behind the pots and actually connects to chassis via the input jack ground lug. Some people solder the ground buss to the back of the pots. I don't. I just float the ground buss above the pots and support it with short wires that connect to the appropriate pot lug and the input jack ground lug. The preamp grounds on the left side of the board also connect to this "Ground Buss". All this is clearly shown on page 5 of the Hoffman_Stout.pdf.

The second ground point is called "Chassis Ground Lug". It is simply a ground lug bolted to the chassis near the PT. Many people use one of the PT bolts for this Chassis Ground Lug. The PT center taps connect to this lug. The cap can negative terminal connects to this lug (If you use individual filter caps then connect the negative lead of all 4 caps to this ground lug). Page 4 clearly shows these grounds. The power grounds on the right side of the board also connect to this lug (see page 5).

The IEC ground wire should connect to a separate ground lug near the IEC connector. Nothing else should connect to this ground lug. This is the preferred way to ground the IEC. (Hoffman simply connects it to the "Chassis Ground Lug.)

The  speaker jacks provide the ground connection for the OT secondary (not really needed).

[EL34]

The pots seem to have 3 groundings, I am a bit uncertain about where the filter cap grounding from the pot would be on the Stout?   

I suppose the CT of the heaters go there to? Then I won't need the 100rs from the pilot lamp?

Are you looking at my layout diagram .pdf file?

You need to look at all the documents for that board on the library page
Steve posted the link

[Oddvar]

Hi and thanks.  Being a hobbyist builder, grounding issues can sometimes be a bit confusing on layouts.  Sorry if it seems untimely. 

This helped.

[Oddvar]

I have now checked all the voltage points as described in the schematics.  Al the voltages ar as described, give an take 5/10%, but mostly a  bit lower.  I am beginning to suspect that the build might be a bit noisy in the first place?  When the volume is a zero, there i s very distinct "G"-ish tone ringing, not so loud as it were.  When I put into it a EL86 tube, it was not lower, but still there.

[EL34]

My build is dead quiet
It's hard to tell the amp is on

[sluckey]

Temporarily disconnect the feedback wire. Any better?

[Oddvar]

No, it's no change. 

[sluckey]

Show us some hi-rez pics of your amp.

[Oddvar]

Could hum come from some fault in either the OT or PT?

[sluckey]

You've had hum in several of your projects. I wonder if there is something common to all your builds that produces hum. Did you ever resolve the hum issues on your other builds?

[EL34]

Could hum come from some fault in either the OT or PT?

Where is the picture that Steve requested?

[Oddvar]

You've had hum in several of your projects. I wonder if there is something common to all your builds that produces hum. Did you ever resolve the hum issues on your other builds?

This is the only amp I haven't managed to get rid of the hum in. 
My builds are:
Fender Bassman, Marshall Plexi, Soldano Slo, Vox AC30, 2 Fender Champ, Fender Pro Jr., Marshall 2204, VHT 10w, Epiphone valve rebuild.  At the moment I am building another 18w Marshall.

I have had issues with some builds, none I haven't managed to solve, some from the good people of this forum, some from others. 

But I am doing this just for fun, as a hobby.  I am no expert at all.

I will post pics in a while, at the moment I am rewiring some parts. 

[shooter]

Soldano Slo

I try and keep notes when I help out, what was the solution on this one, if you don't mind?

[Oddvar]

Two bad solderings on the 0ohm resistors.

[sluckey]

Could hum come from some fault in either the OT or PT?

Yes.

[Oddvar]

Hi again guys.  Just for the conclusion: I changed the volume pot and resoldered one cap and one 100k resistor, and the hum was gone, as mr EL34 stated, I can barely hear that it's on.  Thanks for all your help.

[tubenit]

THANK you for posting your solution and success!   It helps the rest of us when we run into something similar.

With respect, Tubenit

[sluckey]

Always good to know what the solution is. Thanks.

[Oddvar]

Always good to know what the solution is. Thanks.

Thanks to you Sluckey, for all your efforts, hope I didn't strain your patience.