Wednesday, March 11, 2015

Bored With Boards: Repurposing an Ampeg SJ12T, Part 4.

As I've been thinking about this project some more-well, let me back up.

I've suddenly got a lot more time on my hands due to the ending of my teaching gig.

It happened in a way that was proof of the existence of chaos theory if you needed it. There is a meeting somewhere, people sitting at a conference table, and with the scratch of a pen, everyone goes home.

Meanwhile a couple of years down the road and a hundred miles away, people lose their jobs.

But nevermind.  Let me continue-this line of thought leads only to frustration and less money in my bank account.

I sourced out some 50A bridge rectifiers, the kind that are potted in a metal case-it seemed the answer to my problem about building a hybrid circuit board of 6G3 derivation, and also made more room under the hood, thanks to a thread posted by J.R. Frondelli of DBM Audio in the Big Apple concerning the age old question of what to do with a torched Blues Junior.

Being in an optimistic mood, I then decided that I would out source a circuit board for a 6G3 so as to save myself some work.

What I got was a board that was warped and off dimension, and half the eyelets were not installed. The ordinary dimensions of the 6G3 board are approximately 2-3/4 x 10-1/2 and the backing board is the same size. On the other hand, here is what the board should look like, populated. It took me a bit of time to make up a drilling mask, drill the board including larger pass through holes, clean up the burrs with a razor blade, stuff it with eyelets, tape them down and clinch them. Then, clean off the tape residue and stuff the board with components and solder them in.

 It should look like this:

 The red marks were for orientation of the components. The lower shot is the comparison.

Now. How did I do it? It's posted elsewhere on this blog but it consists of obtaining 3 inch vulcanized fiberboard, making a drilling mask from a photograph or screen shot of an existing board, sizing it with a freeware program called Irfanview, printing out a drilling mask on 8-1/2 x 17 inch paper, trimming the board to size, taping and drilling the 1/8 holes. Then you can trim the burrs , install the eyelets and clinch them and stuff the board.

To complete a board like this one, stuffed with the components of your choice once you have paid the one time cost of the tooling and eyelets should cost you less than $20 in parts.

And you'll have exactly what you want, when you want, with no waiting and no shipping or paypal fees. The folks on fleabay will charge you upwards of a C-note plus shipping for something you can knock out all day long for pennies on the dollar.

Haste, in my case, surely did make waste, but as always it's a teaching moment. I'm making all my own boards from now on, thank you.

Thanks again to Jeff Gehring for being so generous in sharing his knowledge.

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