Pork Barrel is super quiet (SOLVED)

[maysink]

Hey, all. I've been digging thru past posts re: pork barrel problems and the issue of voltage keeps popping up but I'm unable to find a list of acceptable values. Using a regulated 9v adapter, I'm getting +9v, VD & VB consistently at all points marked on the schem although VB varies w/ trimpot tweaking.

Anyways, I've double checked all my caps (incl. elctro orientation), diode, tranny and IC orientation. I've fiddled the trimpot. I've swapped out all ICs but the 3101 (as I've only got the one) and the issue remains:

Bypass is perfect. Engaged signal drops to about 10% volume. I can hear the chorus (barely) and I can hear the knobs working (barely). Vibe switch does something but too quiet to tell as does the depth and wet switches. The engaged volume increases slightly with the mix knob dime'd.

Any thoughts before I break out the audio probe and shotgun re-flow all joints?

EDIT: realized I had another MN3101 in my Aquaboy! build. Still quiet. Breaking out the audio probe later this evening!

[jkokura]

That is strange. I would have to recommend audio probing. Unless you're able to do a double check on all your resistors. I had a strange problem with a TS808 build I'm reminded of, in which I subbed a 100K resistor instead of the 100R resistor it was supposed to have. It would be easy to use the wrong resistor in that circuit because there are soooo many of them.

Other than that, I'd start at the output and trace backwards into the circuit. Keep a schem/layout handy and make notes about what kind of sound you're getting at various locations.

Jacob

[maysink]

I decided to check the resistors via color band vs. the BOM. I apparently brain-farted when I put this together as I had R3 = 470 Ohms instead of 470K........

It works now! Got some boring computer book reading to do but did I notice a slight volume drop when the pedal is in vibe mode? Looking forward to playing with this in a day or two. Thanks for the feedback, Jacob.

[jkokura]

Yeah, awesome when it's that easy to fix, but you feel a little silly when you realize how simple. That's why I always recommend the first step of debugging to be a methodical check that you're using the right parts in the right places with the right orientation.

As for the quiet, yes it will be quieter in vibrato mode. With the mix knob maxed it will be close to unity, but it will never boost the signal.

Jacob

[maysink]

Yeah, awesome when it's that easy to fix, but you feel a little silly when you realize how simple.

Totally. I've built several dozen pedals and this is the first time I mis-reisitor'd a part.

Humbling...

I'm reminded of building my BYOC Mouse (awesome pedal, BTW). I populated the board and wired it up in one session and...



nothing. This was before I "rocked before box'd." I tore the whole damn thing apart until I realized I forgot to pop the IC into the socket...........

Where's the forehead-smacking emoticon?!?!?!?