Crawls Backward (When Alarmed)

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Insulating the Pots and Jacks on the Tweed 5E5/5E7/5F4 Clone

One thing I wanted to do on this build is to run all the power supply grounds to one star ground, and the preamp/signal grounds to another separate one.   This, in an effort to keep hum and noise to a minimum. 

So I bought a bunch of nylon washers, intending to use them as insulators for the input jacks and the pots.  However, I realized that even with the washers on each side of a jack, the jack's threads still made contact with the chassis via the hole the jack goes through.   The washers were also so thick that they left only a few threads for the attaching nut to grab on to. 

I needed to come up with a solution to this problem.   What I'm trying is twofold. 

First, I cut a piece of phenolic board and drilled it so I could pass the pots and jacks through it.  The board is the bottom 'insulator' board from a Champ 5F1 circuit board.  It's thinner than the washers, and it will compress a bit when everything's tightened up.    You can see the strip I made for the pots in the picture to the right. 

I'll use the washers on the other side of the chassis, and I should have enough thread to work with.

The issue still remained for the inside of the chassis holes being uninsulated.  I did some research on the interweb and discovered Liquid Electrical Tape!  Who woulda thunk it?  Isn't the interweb great?

It looked like the answer I was searching for.  I procured some at my local semi-independent hardware store...

...and applied it to the chassis holes. 

I masked the outside of the holes so the stuff wouldn't ooze all over the nice front panel.  It's really thick - it comes with an applicator, but it was a bit too big for this job.  So I used a cheap disposible brush to apply it.

I'm going to use the nylon washers under the pots, and since there will be knobs on them, the washers won't be visible.

But I don't want the washers under the nuts for the input jacks, so as an experiment, I put a thin coat of the liquid insulation the nuts, hoping that will insulate them from the chassis.  (If the nuts contacted the chassis, they'd ground the jacks at that point, which I'm trying to avoid). 

The stuff is drying now - we'll see if it actually works.  If it does, I can start the final wiring.


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