cave dweller unity issue

[battlebeast]

So I put a cave dweller together this weekend (first madbean, third pedal) and it worked okay before boxing it up. After initially wiring it up (following the general wiring guide) I was only getting clean signal. After an hour of checking my wiring and not finding the issue I pulled it out and used the beavis wiring guide. And that solved the problem for the most part except that when the effect engagded there is a noticeable drop in volume and the effect doesn't seem as strong as the demos I've seen. I built the cave dweller to spec and I have gone over it looking for errors and can't find a thing. The only potential issue I could see is that I took the pt2399 from a failed deep blue delay I couldn't get working. Is there parts I could sub out to get closer to unity or should I get another pt2399 to try out?

[madbean]

Can you provide a pic of the top of your board?

A faulty PT2399 would not cause a volume drop most likely...it would either pass delay or not. If it's passing delay, I would say that is not the source of the problem.

[battlebeast]

okay, here's a shot of the top of the board. sorry its a little blurry. and I didn't pay attention when I placed my order so its all 1/4 watt resistors.



Also its pretty jumbled up at c10 due to its size.

[battlebeast]

And it is passing delay. It just seems to be a very subdued effect at this point.

[midwayfair]

Check your C3 value again. Make sure it's 4n7 and not 47n. That's one problem that would cause exactly what you're describing.

[battlebeast]

That looks like what I did. Can't believe I didn't catch that. Thanks

[gtr2]

Nice catch Jon!

[battlebeast]

Well that didn't fix it per se but is seems to have turned it into a sine wave version of the atari punk console.  Any ideas what I did now? Or should I just give up and start over?

[midwayfair]

Well that didn't fix it per se but is seems to have turned it into a sine wave version of the atari punk console.  Any ideas what I did now? Or should I just give up and start over?

Sounds like you have something shorting or bridged. Make sure your chip is seated properly and check the back of the PCB for solder bridges. Get out the multimeter and verify proper continuity and voltages if that's not the problem. There's a very limited number of things that can go wrong in this circuit. In particular, I know you'll get distortion if pins 8 and 9 of the IC aren't making proper contact. (Guess how I know all the stuff that can go wrong with this one ... )