On making PCBs...

[Lobsang]

Hi evryone,
I wouldnt call myself an experienced fx builder, but I can now say that after two years I had more hits than misses. However there is a problem, or maybe just a bad coincidence: whenever I build a PCB from scratch, the fx in case wont work as expected or will have a trouble such as volume loss, oscillation, gain loss, dull tone, wrong bias... I also use perf and other type of board which comes with little copper islands around the holes, dont know the name. I never had trouble using this kind of support. Problem comes when I etch the thing with acid and all, you know. M y soldering technique is just right, I even worked with production pedals with no hassle, modding and replacing components. After the etching I make sure the traces are clean, I try them with the DMM but I get same old results... I feel a little frustrated about this. Any hints? Thanx in advance.

[Jay Doyle]

Are these your layouts or ones from the sites normally visited (TonePad or JD's GGG)?

If they are yours, I would start to double or triple check your work before making the PCB, sounds like you end up missing things.

If they aren't yours, I don't know what to say, both JD and FP do great work and their designs are normally tested before they are posted.

I don't think that the PCB would be a cause unless the layout was wrong from the get go. PCB and perf are essentially the same thing, just different ways of doing it.

[Lobsang]

Dear Jay,
I do make my own designs but tell me if I am missing up something: I usually start by placing the opamp if there is one. I put the input on the opposite corner of the output , and close to ground. GND usually takes a big part of the board since lots of things will go here. By the way, I always make sure that NOTHING is shorted to ground unless it has to be. All traces are continuity- tested and cleaned with a steel wool. Components are also tried in a protoboard first so the circuit should work in the first place. As for burning things with excessive solder heat, when I dismantle a non- working board I usually find that ALL components including active ones still work fine. Well, this goes because I am going to put together a really cool pedal with lots of pots and switches and it would be a mess to build on perf... If anybody has a clue on making PCBs that I should know... Thanx!

[Paul Marossy]

The PCB doesn't sound like the problem to me. It sounds more like something is getting inadvertantly grounded or two things that shouldn't be touching are somehow touching eachother, or some wires are too close causing oscillation, or something is getting shorted to ground that shouldn't be which could cause dull tone and loss of volume.

Double and triple checking you own layouts is key here. All the layouts I have ever designed (about 15-20) have worked. A couple that were problematic were so because I made a mistake on the layout. Usually an easy fix. Just because a PCB layout is posted somewhere doesn't mean it's correct. I trust stuff from GGG, Tonepad, GEO and a few others. But using other people's designs can be risky. I make sure all of my designs work before I post them.

All of the above could be part of your troubles in one way or another. Unfortunately, if the schematic you are designing from is wrong, your layout will also be wrong. Once in a while, the PCB design itself could cause problems, although I have yet to have this problem on things I have designed. It's usually dumb stuff like a broken wire, bad solder joint, etc.

[Paul Marossy]

Darn double posts!

[Paul Marossy]

Darn triple posts!  :evil: