1st Combo build – Buff n’ Blend not sending

[Pedal Dood]

 

Hello Barry (et al),

Working on my first combo build (Black Effectors’ Mantra OD and Crystal Octave Fuzz with added Tone Tweq) and I’ve run into a couple of problems. The Main Ins/Outs are wired to the Switcher and the respective BnBs Ins/Outs are wired to the Switcher (in case the photo isn’t clear)

First and foremost,  The BnB’s won’t send the audio signal when the pedal is engaged. When off, the signal travels through all the Ins and Outs & balance pot on the BnB and the 4pdtswitcher.

And I get an audio signal from the send into the fuzz etc. BUT..when engaged, all the INs still work, but the BnB Send dies, and thus no signal gets to the circuits. I tried all the knob fiddling (i.e., ensuring that all the volume knobs were at audible levels) I could think of, and everyone’s getting sufficient power..So I assume I screwed up some grounding, or there’s an In going to the wrong Out and I’m just not seeing it? I admit my soldering ain’t the sexiest (I initially used some truly terrible solder when populating the board), but I’ve delicately touched them up so they should be solid joints..unless ya see something.

I’m at a loss…Thanks for any help

[Barry]

Obviously I am not going to be able to trace the wiring on this but I would first check the voltage at the pins of JFET.

What JFET are you using on the Buff N Blend?

Give voltages:

D:

S:

G:

 

If anyone sees anything by all means..

[Anonymous]

Since we can’t see the wiring, please post a sketch showing the wiring diagram.  I did not understand the routing you described.

[brd]

Hard to see a lot of details. Looks like you used a a tantalum cap for C1 on the buff n blend board. If you did, be sure the polarity is correct. Positive should go toward input or R1.

[Pedal Dood]

Thanks for the reply!

J113

D: 9.16

S: 5.97

G: 3.04

If it helps the diagnosis, the audio signal dies at C1(47n) when the pedal is engaged.

 

[brd]

I’m not a guru here,  but I think the type of capacitor you used for C1 is a tantalum cap and it is polarized. If it is mounted reversed in an audio path, it will block your signal.  If you don’t have a non-polarized cap handy to replace it, just flip that one around and it should work.

Keep in mind you can let the smoke out if you reverse the voltage on a Tantalum cap, that is one of the reasons I avoid them. It wouldn’t hurt to check it with a meter before reusing it.

[Barry]

I believe that C1 is the correct MLCC. Zooming in looks like Code 473 which is 47n.

You are probably are going to need to sketch this out.

[Pedal Dood]

I hope this makes sense.

 

[Anonymous]

I traced your wiring diagram and I did not see any error in what you have presented.  If we believe that the diagram is correct, then we must confirm that the actual wiring is done the same as shown on the diagram.  Here are some suggestions for you to try.

WIth power OFF use a DMM to check continuity.  ALL boards must show continuity to the same ground point.

Then check continuity between each signal path points.  This might reveal a poor solder joint.

Check continuity of contacts on all switches.  A faulty switch could be the problem.

Next, apply power and measure power at each board and verify that each transistor and IC is receiving the correct power at each appropriate pin.

If none of the above steps reveal the problem, then, you may need to start breaking the boards apart and digging deeper into the enclosure.  You will be looking for correct wiring, good solder joints, and no shorting of boards against each other or the enclosure. If you have gained access to the back of the boards, you might as well reflow ALL solder joints on the board while you are there.

If you have been forced to go this far, you may as well consider disconnecting some boards and testing each one individually before reconnecting them to the switching boards.

Advise on your results.

[Pedal Dood]

OK, so I checked continuity throughout, and it seemed fine, But I’m not sure what the ideal voltages are at each pin as these aren’t DIY pcbs, but production circuits for a defunct company, and He’s not offering much more info on the circuits. No schematics, no voltage readings, hell, I had to email him separately just to get the correct pot values..

But, while checking those things, I realized that though I had tested the 3 circuits individually, I never tested the Oct/Fuzz wired to the ToneTweq and hadn’t tested either of the main circuits with their respective BnB. So, I deboxed them and tested them independently, and the Mantra/Buff n’ Blend combo works fine. Though oddly, the BNB LED lights up when the pedal is off and I’m not sure how I managed that little trick as it appears to be wired correctly.

The Oct/Fuzz w/ BnB is still giving me problems as the audio signal still dies at C1 on the BnB board which makes me think I may have effed up the soldering. Perhaps I fried one of the C1 pads while using that terrible solder I had to replace.

I ended up separating them to test, and now the Oct/Fuzz is not working as it did. So I’m going to have to troubleshoot that one before I can get them all back together to troubleshoot the full combo build.

(Why did I pick such a frustrating/sometimes ego-crushing hobby?)

Soooo…Thanks all.

I’ll probably be back here again asking for assistance once I get them all working solo again.

[Anonymous]

OK.  We will be here to help.

[Author]

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