NoMoJo Tonebender issues

[p_wats]

A few years ago I built the initial NoMojo fuzz board that I got as part of the Function F(x) fundraiser as my first SMD project. I recall it working somewhat, but one side having issues and not knowing how to troubleshoot SMD very well. Fast forward to now and Stomptown was kind enough to send me an extra NoMojo board, so I could try again.

The Fuzz Face side works fine and the Tonebender side was good initially, but then I biased both and now I get nothing out of the TB side. I seem to recall something similar happening the last time. Is it possible that my biasing could have fried Q2 or Q3?

Continuity traced well. Using a probe the signal seems to die around Q2/Q3. The bias 2 trimmer has very little effect.

I'm pretty sure I used 5088s on this board (whatever was provided in the group buy parts kit from years ago).



(I cleaned the board with isopropyl alcohol--it just looks dirty in the photo for some reason)

I can't lose this battle twice so any suggestions are appreciated!

[p_wats]

Did some more probing tonight. I'm getting a good, loud signal off the collector of Q3, that reacts well to the attack control, so that's promising. The signal is strong going to pins 1 & 2 of Bias 2, but all but dies at pin 3.

The signal at Q3 can be affected by the bias trimmers--the volume can be reduced--but the full volume signal never makes it out of the bias 2 trimmer, now matter how the two bias trimmers are set.

(I also reflowed all joints and replaced Q1 & Q3, just to be sure.).

[p_wats]

I've got a decent fuzz sound now after reflowing/re-seating some components (this is all meant to be SMD practice, so here we go).

However, when I set the bias to the most pleasing fuzz sound the volume is lower than unity.

Not sure if anyone who has built one can chime in to compare, but I'm curious if 2222a transistors would help with that in comparison to the 5088s that I've used (by contrast, the Fuzz Face side is very loud).

In any case, I figured I'd keep adding details here in case anyone stumbles across this and finds it useful.

[p_wats]

A smarter person might have left this alone and moved on by now, but I'm clearly not that smart.

I replaced all the transistors with 2222a and rewired all off board connections. I also replaced the attack pot, as it was an old one. For a minute, I thought it was working, albeit still not as loud as the fuzz face side, but I came back to it today and it's again crackly and intermittent.

That tells me it's a loose connection somewhere, but I've reflowed/replaced parts so many times now it's hard to say what else I can do aside from starting fresh (again).

Call me stubborn, but this is the second NoMojo board I've tried where the FF side worked straight away the TB side never got going properly. I suppose it's possible the parts selection I got from a kind soul was mislabeled (how do you check SMD caps?), but I assume we'd have heard of others having issues too.

In any case, I'm talking to myself on this thread. I'll likely try to remove the components to at least get some hot air reword practice, or toss it (again) and never speak of this circuit again.

[gordo]

This was my introduction into smd builds and I was amazed it ever worked.  Mine has the very common Fuzz Face phenomena of being at about unity volume with both knobs maxed.  I've yet to build a FF that I didn't wish had a bit more output.

The Tonebender side hits this level about 2/3's of the way up on the volume knob and gets plenty loud after that.  It does do the sputtery gated thing as you turn down the guitar volume.  Neither side cleans up noticeably well but the FF gets more into the overdrive zone at lower guitar levels.

Wiring a double sided board ends up looking like the dog's breakfast on the inside but it works...

[p_wats]

This was my introduction into smd builds and I was amazed it ever worked.  Mine has the very common Fuzz Face phenomena of being at about unity volume with both knobs maxed.  I've yet to build a FF that I didn't wish had a bit more output.

The Tonebender side hits this level about 2/3's of the way up on the volume knob and gets plenty loud after that.  It does do the sputtery gated thing as you turn down the guitar volume.  Neither side cleans up noticeably well but the FF gets more into the overdrive zone at lower guitar levels.

Wiring a double sided board ends up looking like the dog's breakfast on the inside but it works...

Very interesting! Thanks for the input.

My Fuzz Face side is super loud---well above unity, but the TB side has never worked on 2 builds in a row now. I'm going to give it another shot, before then using it as practice for my hot air station, to see if I can remove the components and start again.

The funny thing is I don't actually care about this build---I just want the practice---but now that it's not working it's bugging me to no end. Ha

[madbean]

Honestly, it's been years since I've built, thought or looked at this one. But, Dave designed it and I can ask him to take a look at this thread to see if he has any feedback. I know my own build worked without issue but it's buried somewhere under a pile of circuits, I'm sure.

[p_wats]

Honestly, it's been years since I've built, thought or looked at this one. But, Dave designed it and I can ask him to take a look at this thread to see if he has any feedback. I know my own build worked without issue but it's buried somewhere under a pile of circuits, I'm sure.

Thanks. I tried to message him, but I'm not sure it went through (I don't see it in my "sent" messages, but I've seen that happen before and it seems to only appear there after the person read/replied---same happened before when I messaged you a long time ago about the old Moodring board).

In any case, I think I have to back away from this one.

As it stands now I've removed all the components and started from scratch, but something is wrong around C7, as I'm getting sparks/smoke from that cap. I think the pads may be making an intermittent connection somehow (I've removed the cap, cleaned tested and checked the pads for continuity 3 times with the same result once the cap is reinstalled). I also removed C9, just in case and used an exacto to try and separatethe pads more, but still sparking and now it looks like a mess.

I'm out of some of the components now and can't go any further anyway, so time to move on and never speak of this board again!

The good news:

- I got some SMD practice, as was the goal, and got the FF side working no problem.
- I also got some practice removing/replacing SMD components
- It gave me a chance to try removing everything using my hot air station, which was fun to test

Thanks to those who chimed in!

[madbean]

I emailed Dave to ask him to check in on the thread. If I have tomorrow I'll look over the design/docs again. Just can't tonight.

I'm pretty sure I have some of these boards left, actually.

[gordo]

Here's a gesture if you're up for it:

Brian was nice enough to PIF me a few boards and I've been mulling over what I can do in return.  You're more than welcome to my build if you'd like it.  Just PM your address and it's yours.

[p_wats]

Here's a gesture if you're up for it:

Brian was nice enough to PIF me a few boards and I've been mulling over what I can do in return.  You're more than welcome to my build if you'd like it.  Just PM your address and it's yours.

That is very kind of you to offer! To be honest, I never really "wanted" this circuit anyway, as I'm sorted for fuzz sounds. I just figured I'd try it out for the SMD practice, as I just ordered some of my own PCB designs for the first time and added a hybrid SMD/THT layout as a variation for fun.

I emailed Dave to ask him to check in on the thread. If I have tomorrow I'll look over the design/docs again. Just can't tonight.

I'm pretty sure I have some of these boards left, actually.

No worries to bother Dave. My board is no longer salvageable and I've started to dismantle it in a cathartic act of letting go.

Like I mention above in my reply to Gordo's generous offer, this was all about the practice working with SMD anyway, which I feel has been achieved (though I probably need more practice. Ha). I've been eyeing a few other projects on the site, so maybe I'll see if I can buy another board from you with a future order (I'm liking the look of the new FV-1 project and am curious to try the relay bypass boards). Thanks!

[gordo]

Gotcha, if you change your mind it's yours.  I was of the same mind.  Once you've built a few FF and TB it's more of the same, but this one was a stepping stone for smd.  The fact that I really liked it was just icing on the pcb.

[pickdropper]

Here's a gesture if you're up for it:

Brian was nice enough to PIF me a few boards and I've been mulling over what I can do in return.  You're more than welcome to my build if you'd like it.  Just PM your address and it's yours.

That is very kind of you to offer! To be honest, I never really "wanted" this circuit anyway, as I'm sorted for fuzz sounds. I just figured I'd try it out for the SMD practice, as I just ordered some of my own PCB designs for the first time and added a hybrid SMD/THT layout as a variation for fun.

I emailed Dave to ask him to check in on the thread. If I have tomorrow I'll look over the design/docs again. Just can't tonight.

I'm pretty sure I have some of these boards left, actually.

No worries to bother Dave. My board is no longer salvageable and I've started to dismantle it in a cathartic act of letting go.

Like I mention above in my reply to Gordo's generous offer, this was all about the practice working with SMD anyway, which I feel has been achieved (though I probably need more practice. Ha). I've been eyeing a few other projects on the site, so maybe I'll see if I can buy another board from you with a future order (I'm liking the look of the new FV-1 project and am curious to try the relay bypass boards). Thanks!

Sorry, I haven't been on the board much lately.  If your board is toast, I am sure one of us has another one we can send you.

To answer your first question: I don't really see how the biasing could cause the circuit to stop functioning unless the trim pots themselves failed.  If you hadn't taken it apart, I would've suggested audio probing to see exactly where the signal stops.  Also, the board looks pretty clean.  If you washed it, did you do that before or after the trim pots were added?

[p_wats]

Sorry, I haven't been on the board much lately.  If your board is toast, I am sure one of us has another one we can send you.

To answer your first question: I don't really see how the biasing could cause the circuit to stop functioning unless the trim pots themselves failed.  If you hadn't taken it apart, I would've suggested audio probing to see exactly where the signal stops.  Also, the board looks pretty clean.  If you washed it, did you do that before or after the trim pots were added?

Hey! No problem at all. Thanks for chiming in. I swear I build enough that I can usually troubleshoot any issues on my own, but I was just stumped by this being the second TB side of this board that I couldn't get going, even though the FF sides always worked first time .

The trimpots were pretty much the only thing I didn't try replacing, as they seemed to be functioning fine. In the end, I fluxed and reflowed all joints, replaced transistors a few times (including different types), removed all components with a hot air station and re-populated the entire thing and probed/measured in between each stage, with varying results.

I have to assume it was poor SMD soldering on my part that kicked this off and call it a day (though the FF side looked no better and worked fine).