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Howdy folks, I've built the Aion L5 preamp. Having a little trouble. One thing to note- I generally mount pots in the enclosure, then put the PCB on and solder.   I snapped photos before doing so.   Good news is, all of the knobs and switches do actually perform their functions. However, I'm having some issues with the unit sounding horribly splatty/spotty with the limiter engaged. Any amount of gain reduction results in a nasty electric buzz that sorta pulsates as the gain reduction goes away.   

I have some metal can CA3080s, and I initially put them both in backwards. Oops. The pedal didn't work, and the limit light stayed on all the time regardless of where the limit knob was set. Both got extremely hot to the touch. I'm pretty sure I killed them. I put a new one in the IC11 spot, this time oriented correctly, and the limit light issue resolved. I am still having an issue in that IC10 gets VERY hot. I had an NTE902, which is a rebranded CA3080, all shiny and new, and put it there. Now I'm sure it's roached as it got really hot and darkened.

The voltages on QX1 & QX2  are way off.   I've gone through and looked at the resistor color codes around those, just hoping I'd find something obvious.   All are correct.  Solder joints look good.  I've double checked all the electrolytic cap and diode orientations and they're correct.   

What's driving me nuts is I checked every single resistor and capacitor with a multimeter before install. It is still possible something was missed.   Hoping someone can point me in the right direction to look.   All of the knobs seem to work, but the sound is problematic. I've used NE5532 in place of the 4558s in all positions. Everything else is as spec'd.   At this point I'm stumped.   The pedal is a bit noisy, but the preamp section sounds good.   I'd just like to get the limit circuit to work.   Any suggestions you might have would be appreciated.   Voltages below:

According to the test chart:

IC10- (CA3080E)
1- 0
2- 0
3- 0
4- -15.2
5- -14.5
6- 0.9
7- 14.73
8- 0

IC11- (CA3080E)
1- 0
2- 0
3- 0
4- -15.2
5- -14.62
6- 0.23
7- 14.73
8- 0

QX1- (2N5088)
1- 0.4
2- 0.9
3- 14.66

QX2- (2N5088)
1- -0.22
2- 0.4
3- 13.21


Actual measurements:

IC10 CA3080

1   -50mv (goes down)
2   -14mv
3   0
4   -15V
5:   -14.5v
6:   2.07V
7:   15.26V
8:   cycles down to -300mv

IC11:

1   23mv
2   0
3   0
4   -15V
5   -14.40
6   fluctuates
7   15.26
8   0

Qx1:
1   12V
2   12.5V
3   15.19V

QX2:
1   10.9V
2   11.4V
3   28mv

That did the trick!!   Just replacing my tip and reflowing a few spots was all it needed.  Been working for about an hour now, just in time for band practice.  Thanks much!!

Yep, now I'm getting .74 at pin 7 on the pt2399.  Ic1 voltages are normal.  I can't seem to get the dry to reappear sadly.    Would you suspect the blend pot given that the dry doesn't show up on any of its legs?   I dunno kinda just spitballin'.   

Figured it out sorta.     R25 had a 470k resistor instead of a 470 ohm.   Thought That did the trick, but after a couple minutes playing it after boxing I stopped getting any dry signal.   I unboxed it, thinking maybe there was a short, but nope, same issue.   I probed the blend pot and it's wet on all three pins.  I'm kinda at a loss where to go from here.  Any suggestions?   

 Well, I tried reversing the polarity of the LED, and it's exactly the same either way. Hmmmm.  Guess it's audio probe time.   Still if anyone has any ideers I'm all ears. 

Howdy friends!

So I recently attempted to build a dirt baby, and I'm having an issue. What I get is no direct signal; just one small, very quiet, very dark repeat, but that's it.   The speed of the repeat is affected by the delay time, the modulation works (as does the vibrato/chorus switch), and the trim does affect the volume of the repeat.    So that's encouraging. 


I have checked all of my voltages which I will list below. They all look to be right in the ballpark and seem appropriate given that this is the latest dirtbaby PCB.  I've checked over my solder work using my super nerdy jeweler's visor, and I do not find any bridges, no missed points, etc.   I made sure to isolate the pots from the PCB with double sided tape.  I've double checked my electrolytic cap orientation, and the only value sub I have done is 30pf instead of 27pf  in C2.   You will see that that one is soldered on the opposite side of the board as it would normally be. The reason for this is that I was attempting to find a 27 pF cap, and continued populating, however those have been tough to source.  Otherwise all stock.   

The only thing I am thinking is that  either that substitution is a much bigger deal than I thought, or, more likely,  I may have gotten the LED polarity wrong for D2.   I have the flat side on the left (the square pad), and now that I think about it, I think it should be oriented with the flat side toward the flared graphic on the PCB.   If this is wrong, I'll fix it first before doing the ol' audio probe.   

I have no problem digging in and pulling that out, question is, would that cause the issue I'm having here? Does it have to be a diffuse red led as opposed to a clear one? 

In the interest of full disclosure, while I am always in the rock before box mode, with this, I did sorta "half" box it, as I really wanted all the pots to be straight in the enclosure when I soldered them to the PCB.  This is to alleviate an issue I've had where I solder the pots in and then they end up a little or a lot crooked.   That said I did so with a purpose and with my eyes open, and I've taken it out and am now attempting to trouble shoot.   My pedal doesn't work but at least the damn pots are straight!!!

Voltages as follows, 9.6 v power supply:

IC1:
1: 1.66
2: 3.11
3: 3.10
4: 0
5: 4.55
6: 4.59
7: 4.51
8: 9.51

IC2:

1: 5.08
2: 2.55
3: 1mv
4: 0
5: 2.93
6: 2.54
7: 1.09
8: 0.74
9-16: 2.55

Ic3:

1: varies
2: 4.72
3: 4.3-5
4: 0
5: 4.72
6: 4.74
7: 4.5-5
8: 9.47

IC4:
1: 4.6
2: 4.61
3: 4.18
4: 0
5: 4.42
6: 4.63
7: 4.63
8: 9.5

Regulator:

1:  9.5
2: 0
3: 5.07

Verified the voltage coming in is correct. 
Thanks!!! 

Yes indeed!   

Thanks much to m-kresol's help with a capacitor question.  Here is my Mudbunny build to Skreddy P19 specs.   Not as much gain as I would expect in a muff,  but what's there is killer sounding.  It also sounds great after my overdrive, especially when I hit it hard.  This sounds much more like a distortion than a fuzz to me.   One slight snag:  the treble is pretty high on this pedal.  Mostly I run it off or just above off.  At zero there is a slightly different character to the pedal's eq overall than if I put just a touch of tone on it.  Interesting.  I don't think this is a normal aspect of the pedal.   But all in all, I'm pretty pleased.   

Will do!

Worked a treat.   Pretty much an amazing pedal. 

Well, I used my multimeter in both Dc and ac, and it Looks like it's equal on both sides.   I'm going to install it the way you've suggested, and see how it goes. 

Wow.  Great answer.   Thanks so much.  I've been an assemble by numbers guy for the most part but I can see how running into problems can be extraordinarily instructive.   I think I'll do just what you recommend as far as the testing goes. 

Thanks for the response!   Would you be able to tell me the reasoning behind that choice?   . Just trying to learn. 

Hi everyone, new to the forum. I did a search on this and didn't find the exact answer to this question.    I'm doing a P19 style build on the Mudbunny PCB, and it looks like for C12 I grabbed a tantalum.   It's polarized, and my understanding is that it's ok to use there, however I need to determine where to orient the positive lead.  Any ideas?