Signal and chassis grounds?

[Jim R.]

Can somebody tell me at how many places are signal grounds connected to the ground plane, and where?

Also, would their be any benefit in lining the inside of the chassis sides with copper foil and then connecting it to the ground plane?

Thanks,

Jim

[Paul Birkeland]

Can somebody tell me at how many places are signal grounds connected to the ground plane, and where?

Terminals 13 and 23 would be those points.  Other points are used for safety ground against the chassis.

Also, would their be any benefit in lining the inside of the chassis sides with copper foil and then connecting it to the ground plane?

If the copper doesn't conduct to the aluminum plate, then you have removed the safety ground from the chassis plate, which is a problem.  Copper also oxidizes in a pretty nasty fashion, so you'll have to start with a coated foil, then scrape off the insulation where you want to connect your grounds, then reapply some kind of coating once your connections are made. 

[Jim R.]

Hi PB,

Yes, I'd absolutely make the foil shield part of the safety ground. I also have a nice metal lacquer to apply to the copper after it is appplied and attached to the safety ground. I think this particular copper is coated anyway as it has been on my workbench for years and shows no sign of corrosion.

Thanks again,

Jim

[Paul Joppa]

Don't neglect ventilation.

[Jim R.]

Paul,

No worries, this foil is only going on the inside of the wood chassis so it won't interfere with ventilation in any way.

I'm also building the amp on a 10" x 12" chassis and I'll be adding some extra ventilation slots as well. A friend of mine is going to lay all this out in a CAD system with me telling him where things will go in the larger format, then we'll just take the drawing file and plate over to the local water-jet place to get the plate cut. I was going to try to mill the whole thing on my drill press with a cross slide table, but decided against that. :-).

-- Jim

[Tubejack]

It was probably overkill, but on my EROS build I did line the inside of the base with copper foil and installed a bottom made from double sided Cu PCB, all(http://) tied to the chassis ground.
Never had a ventilation issue .....