Thread: Vox mini 3 amp
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Old 06-27-2013, 12:53 PM   #33
midibob
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Join Date: Nov 2008
City & State: London
Posts: 250
Default Re: Vox mini 3 amp

OK, at long last I have produced the daughter board. Making the printed circuit has been a very long process but that's another story.

I've attached a picture of the board and am testing it at present as I only finished it this afternoon. This is the 2nd attempt as the chip had too much gain so I had to redraw and etch new boards to hold the extra components.

One slight snag so far, there is a cap across the chip power rails and I've found the ESR of it isn't low enough which causes break up at max volume. Other than that it appears to work fine.

The plan was to have a board that would replace the original o/p chip without having to desolder it and not to have to modify the board by drilling holes, also not needing any special tools to accomplish it.
All it takes is the removal of the two electrolytics C17/18 and lifting the speaker connections off the old board and adding the power rails via holes that are already in the main board.

Hopefully all I need now is to find some lower ESR 10uF caps and I think it's finished.

Midibob
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