Powder Coat Grounding Question

[schweigc]

Hi all, I am starting to build my Crack-a-two-a. I am having the top of the chassis and the outside of the bell powder coated. Where will I have to make to scrape the paint for grounding and wiring purposes? I am excited about this amp and can’t wait to hear it.
Thanks for your help

[Paul Birkeland]

It's easy enough to just do the middle lug of each 5 lug strip, as well as the area around the #8 screw back by the IEC inlet.

While one of the middle lugs of the 5-lug strips isn't used, it will be a pain to do them later if you mix them up, so I'd do them both.

It's also very helpful to pass a 1/4" drill bit through the power transformer mounting holes after powder coating to resize them properly to allow the hardware to work.

-PB

[Lee Hankins]

If you are only having the top of the chassis powder coated then you do not need to do anything to the chassis, the uncoated  bottom is the ground plane, this is why star washers are used on all ground lugs, etc. on all Bottlehead kits.

I have a powder coat system; there is always overspray so I always end up sanding the bottom of the plate.  The first time I powder coated I taped the bottom of the chassis plate as done with spray paint, big mistake.  The openings in the chassis were plugged with hard powder and even using powder coat tape it was a pain to remove.  The openings need to be clear of any obstructions, resulting in overspray and sanding with orbital sander, makes for a extremely nice smooth looking bottom plate.

[tubes_for_me]

Hi. I was reading this post but wanted to make sure. If I read this right, there are five spots that need to be kept finish free - the four 5-lug strips and the area around the #8 screw. I think the underside of the transformer hat, around the mounting holes, also needs to be kept uncoated too. Is this correct?

Thanks for the reply. I was also looking at powder coating and wanted to make sure I didn't cover up where I need to ground.

May I also ask when the stepped attenuator upgrade might be coming?   

[Paul Birkeland]

Hi. I was reading this post but wanted to make sure. If I read this right, there are five spots that need to be kept finish free - the four 5-lug strips and the area around the #8 screw. I think the underside of the transformer hat, around the mounting holes, also needs to be kept uncoated too. Is this correct?

The transformer is actually isolated from the chassis, then the stack is grounded directly to the safety ground, so you can powder coat over those holes.  Do be aware, however, that you may want to pass a 1/4" drill bit through them by hand afterwards to help make sure the shoulder washers still fit.

May I also ask when the stepped attenuator upgrade might be coming?   

We will be looking at putting this out this year most certainly, and more than likely in the spring/early summer. 

-PB