Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: WillieBoy on November 24, 2010, 06:38:56 pm
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On the lower right hand of the board, there are 5-22uF Electrolytic Capacitors in a row. On the schematics (new and old), it shows them going from a lug out into space where there is a ground. I don't see a post for a ground leg, how did everyone else do it?
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The caps can either be mounted on a dedicated board and go into a top-mounted doghouse (removed here)
(http://www.qrp.pops.net/images/2008/tube_amp/AB763.JPG)
(from http://www.qrp.pops.net/tube_amp.asp)
or be connected Doug's style:
(http://www.el34world.com/Hoffman/images/IMG_0633.jpg)
Some more info here: http://deluxereverb.waynereno.com/index.html
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If you are asking where you ground the capacitors in the doghouse, I routed the ground wire to PT and connected it to one of the mounting bolts. In older fender amps they brought the ground wire inside and soldered it to the chassis.
Mikeys builds are really nice....
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Thanks all, I see it now. Must have been very tired last night after staring at the layout all day. A picture really is worth a thousand words! For some reason, I thought the 5-22uF caps were 22uF 25V caps that I had been installing all afternoon, rather than the big filter caps from the doghouse.
I was sort of frustrated that I had not bought enough caps, which I guess should have been my tip off.
Now I just need to do a bit more schematic work to determine where to wire them from the doghouse to the board.
I can tell that I really have a lot more work to do to truly understand amps.
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When you emailed me about this, I thought you were asking about the small 22 uf caps that are mounted parallel across the resistors on the board.
A picture really is worth a thousand words!
There are pictures in the library of boards, you just have to spend some time there to get the info.
How about these links the Hoffman Bord Information section
What is a hoffman board
http://www.el34world.com/boardmaker/oldboardkitpage.htm
You can see my AB763 project on this page
http://www.el34world.com/Hoffman/ampphoto.htm
How about this one down in the Helpful info items sections
Filter cap hookup solutions
http://www.el34world.com/charts/filtercaps.htm
and many other pictures linked off the library page.
If you explore the library pages, you can make bookmarks to all the pages you need to go back and read