[sdiy] PCB layout mistake = Aaron curls up in a ball in the corner and cries

[Cynthia Webster]

Hi Aaron!
Stay true to your vision and don't turn it into a Frankenstein, you'll 
never now exactly what's going on
with all that mishmash of jumpers and spliced traces.

After a very long sigh... I would just suck it up and simply redo the 
layout and make another board.

I'm sure your frustrated, take a nice long walk and think of the shiny 
new board - free of all of those errors
that you'll have coming.

Cynthia


Aaron Lanterman wrote:
> Feeling overly confident from the success of my Music Easel LPG layout 
> (youtube video to come when I get around to it), I was really excited 
> when five new boards (preamp & env det, pulser, envelope generator, 
> timbre circuit, and balanced modulator) came from PCBCART last week, 
> and I happily built, built, and built. I need to order a few strange 
> resistor values and various pots, but I'm close to being able to start 
> testing everything.
>
> Then, while viewing the schematic of the timber generator, I realized 
> to my horror that I had the +/- on four op amps switched. The feedback 
> was going the wrong direction. How could I have not seen that before 
> in all the time I've spent staring at the schematic? Hmm, I'll need 8 
> jumper wires to fix that. Bad, but still doable.
>
> Then I reviewed the others. The pulser, envelope generator, and preamp 
> & envelope detector have op amp inputs OK. But on the balanced mod - 
> oh hell, I screwed up the inputs of 11 of the 12 op amps. Aaack, that 
> would require 22 jumper wires! *hits head repeatedly into wall*
>
> What makes it worse is I have a vague recollection of actually 
> switching the op amps from the correct way to the wrong way at some 
> point in a severe brain fart moment.
>
> AAAAAAAAAAAAAAAAARG!
>
> That's a couple hundred down the drain.
>
> I figured it out before I started testing, but I still have most of 
> the parts in. My plan is to solder in the vactrols with only a few 
> leads in, so I can clip them back out and reuse them (I can't imaging 
> committing 7 expensive vactrols to a board that requires 22 jumper 
> wires, which I can't imaging are very stable).
>
> But I do want to try to test everything, so that when I fix the op 
> amps I can fix other mistakes I find to.
>
> So what's the best approach to actually getting a prototype running?
>
> 1) I was thinking of dremelling the traces, but then I thought a 
> quicker solution would be to just clip the input leads on the ICs 
> where the ICs meet the board.
>
> 2) If I take approach 1, is there a "best practices" for soldering 
> jumper wires on top of ICs? I imaging it will be hard to make a stable 
> connection
>
> 3) Instead of 1 and 2, maybe I should unsolder the op amps (I 
> generally solder chips straight into the board without sockets, unless 
> it's a particularly expensive chip to replace, or failure prone like 
> CMOS), put in sockets, and build some "pin switchers?"
>
> - Aaron
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