Blender problem: Wet signal not going away

[MrStab]

hi,

as per another thread, i managed to get my act together & improve the layout for my attempted blend pedal. summary: it wasn't going to so badly, but as it's my first build i did a scruffy job of it, had a lack of foresight and it all screwed up when i tried re-assembling the case, so i started over (although my buffer circuit was intact). i figured this warranted its own thread as i couldn't find any similar posts, or the right keywords. scroll down for a sorry excuse for a layout. i'm not taking any photos as the resulting mockery would hurt my manhood. lol

so i got everything working again briefly, disconnected the old pot i was using to troubleshoot another (crackly), unsoldered & repositioned some wires (trying to be meticulous as i went), and now the wet return signal dominates the clean buffer signal, no matter what position the knob is set to. tried different pots, even different lugs for the f- of it. at first i thought the return signal was totally cancelling out the clean, but i i ruled that out as lowering the volume somewhere within the FX loop allows both signals to be heard. that and the fact it worked before on several occasions make me wanna rule out any phase issues.

possibly-handy info:

• wet & dry work fine separately
• both signals are (or at least seem to be) present, as lowering volume in FX Loop indicates.
• 3 different (linear) pots make no difference, skipping the pot altogether makes no difference.
• i get the trademark guitar-lead buzzing when i touch the lugs for clean and output (2 & 3?), but not with the connection from fx return. cutting the return signal stops it & leave the clean audible again (as it should). if this helps in isolating it any.
• everything seems grounded properly (or so i think...)
• not to be confused with "wet overpowering dry, fix with resistor" problem, as the problem is the wet not shutting up, as opposed to being too loud.
  
• if you turn the pot into just a volume pot for the return and put the buffer signal straight into the output, turning the pot turns down both. weird!
• nothing seems to be touching (that shouldn't be touching) on any of the inputs, DPDT switch etc.
  
• i've just remembered: touching some of the grounds makes hot-wire-like buzzing when touched, yet they all act as ground. is that normal? <<< novice.
• it worked before! lol

check out my amazing masterpiece of a diagram:


http://i.imgur.com/u4QxXJF.png

any help greatly appreciated, i'm so close to completing this catastrophe of a project after over a week! lol

[MrStab]

i know this is probably bad etiquette, but i'm at such a loss here...

*bump*

*hangs head in shame*

[Mark Hammer]

Being desperate is not bad etiquette.  Not thanking people when they eventually help you, several posts from now, IS. 

It might help us to know what it is you're blending.  I've read over the post a couple times, and I can't seem to find it.  Some blending tasks want a different arrangement than others.

The circuit also doesn't seem to have enough parts.  I realize it is somewhat risky on my part to infer the circuit/schematic from the drawing, but that's my initial impression.

[MrStab]

hi, thanks for the response! rest assured, i'm a grateful kind of person. lol

i THINK i've actually cracked it - i thought to myself "this sounds like what happens when you try to do a passive blender"... and sure enough, despite no obvious-to-the-eye problems, there was a problem with the buffer as jostling has suddenly brought it to life. still kinda weird, though - it was ruling problems with the circuit out at first because it was coming through earlier fine, when the fx return was disconnected, but i was also having feedback into the bypass "channel" at some point when i was diagnosing.

i'm testing with a crap multi-fx rig, at the moment just with delay but i've been flicking between different patches. i settled on pure & simple delay just because it'd worked on the "prototypes" and as far as i could tell had no issues of its own in this situation at least. the eventual idea is to make up for my amp head's serial fx loop (hence lack of blend control), but it's turned into more of a fun way to waste time as i doubt it's stageworthy. lol

the buffer circuit, as far as i can tell, is more or less the "minimal blender" found on Sean M's site, although as you can probably tell, i lifted that schematic from muzique.com. it's the most basic buffer layout for fools such as myself. *sigh* i don't wanna seal up the box and class this as "finished", hoping it'll just stay in the right position. not that i'd ever use it in a situation where i could get sued for deafening people, but it'd be cool to actually be able to rely on my first project. guess i'll check the tips here on debugging and see what i can find out... any more tips or suggestions?

[MrStab]

just a few observations from a beginner to help any internet archaeologists from the future, as i couldn't find exactly what i was looking for myself. please feel free to correct & explain anything!

if your buffer has sound coming out of it, particularly without power, it doesn't mean that it's working.
also, feedback from lack of buffering seemed able to permeate even the bypass channel (in this situation, at least). this had me ruling out the obvious for days. learn to solder properly(ish), don't screw up your iron(s), and limit yourself to softcore pharmaceuticals. lock all firearms and ammunition in separate rooms. lol

just a quick question, which i've read a few threads/articles about, but i'm curious about this particular setup:
i have a "pop-less" circuit for the LED, but i was greeted by a nice loud footswitch pop in front of a 4x12 cab when i decided to take the pedal beyond my practise amp. in the interests of preserving tone, could i avoid a pulldown resistor and just wire the DPDT switch so the signal goes to ground in bypass? would i be doing that to the battery pins or the signal pins (see diagram in original post)?
cheers again