# Same old parentheses fuzz octave issue.



## jcrews (May 4, 2021)

I dug thorugh some older threads but most are for the older board.  I used 1N34A diodes across the board in D1 D2 and D8 and D9.

It seems like I have the same issue. (no octave effect and turning up the octave knob cuts volume)

I just didn't see where we landed because I'm not using old school russian stuff.  I grabbed what was sold as GE 1N34A, but they look just like my silicon diodes.  Pic attached.

My first guess is to swap those around.  I'm assuming if they are marked backwards from what the circuit calls for, it wouldn't matter in the clippin section because all that matters is they be installed in opposite directions?

I'm going to try that first and report back.  If there's any other reason for the the whole "octave knob kills the output" issue everyone seems to have.... I'm all ears 

Thanks,

p.s. everything else works and sounds flawless.  Love the rat and the boost.  Really wanna hear the octave as that's the only "new" thing for me on this one.


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## jcrews (May 4, 2021)

update:

i swapped in some new 1N34A's into D1 and D2 and oriented them backwards to the screen print.  Black band facing down instead of up.

It's doing almost exactly the same.  No octave sound and turning up the octave kills the output as you go..... But now it's def also bringing up a hum that's louder as the output volume drops.  So im assuming i had these right and it's something else?


Crap.

Any advice?


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## Chuck D. Bones (May 4, 2021)

Have you visually verified that all of the parts are the correct value/part number and all solder joints are good?  Check the ends of the ribbon cables, they like to break if flexed too many times.

Those look like Silicon diodes, which will work fine, but D1 & D2 need to be oriented correctly.  They are correct in the top picture.  They are backwards in the bottom picture.  Correct the orientation of D1 & D2 as required and after that, resist the urge to unsolder stuff until we know what's wrong.

Do the Boost and Distortion functions work?

If you measure these voltages, we can see the state of health of the Octave section.
Q3-E
Q3-C
Q4-E


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## jcrews (May 5, 2021)

Yeah the whole pedal works great just not the octave.  I have flipped them back the right way.  This seems to happen in about 50% of these builds.  I ordered the Mojo russian DE9's but everything else has been verified and tested.  As soon as i get back to my notebook I'll post voltages.  The markings on the screenprint were fixed for V2, but i thought.... even if my diodes had the cathode on the wrong end, I wouldn't know without switching them because they would still function fine for clipping in D8 and D9.

Had I researched a bit more, and read the 10+ threads about this issue, i might have skipped this one.

When my pack of russian fancy pants diodes show up, I'll socket all 4 diode spots so I can swap em in and out until i find some that work without having to take the thing out every time.


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## jcrews (Jun 8, 2021)

Reviving a dead thread.

UPDATE:  I went back in and socketed both germ resistor spots (since nothing else was giving me any trouble)
As y'all predicted I busted BOTH ribbon cables doing this (last time I'll ever use them).

I have a bag of fancy russian diodes in front of me, a properly wired parenthesis fuzz and the octave is still doing the same thing:
No octave sound and the more i turn it up the lower the output gets.  

Can i get any guidance here?  I have my meter out so I'm happy to take voltages from anywhere and post them.  I have triple checked all my work and I can't find anything wrong.  I have read the 20+ threads about this, and I'm assuming i have a dead transistor somewhere OR i didn't "measure voltage" and match my diodes.  

Any suggestions would be greatly appreciated.  The rat and the boost sound SO good.  I really wanna hear the octave.  I already have rats and boosts, so this is kinda why i built this one.


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## Chuck D. Bones (Jun 8, 2021)

Try Schottky diodes in the octave section.  Russian diodes are leaky and you don't want leaky diodes here.

Measure: 
Q3-E
Q4-E


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## jcrews (Jun 8, 2021)

Ha.  Dammit.  I was under the impression it WANTED to see leaky russian diodes like the Original.  Any specific diode number to try?  I have quite a variety on hand.  I'll get the measurements.  Just power to the box first?  Will i get diff reading with the effect engaged/disengaged?


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## Chuck D. Bones (Jun 8, 2021)

Power on.  Engaged/disengaged doesn't matter.  1N5817, 1N5711, BAT-41, BAT-42, BAT-46 will all work.


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## jcrews (Jun 8, 2021)

ok right now as it stands (with the leaky russians) im getting:
Q3 E: 8.9 volts
Q4 E: 3.8 volts

I'll toss some BAT-41's in there now and edit this post with their numbers

EDIT: q3 E: 8.9 volts
          q4 E: 3.7 volts


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## Chuck D. Bones (Jun 8, 2021)

Q4 is good.  Q3 is not.
Measure 
Q3-C
Q2-C (same as Q3-B)
Q2-B


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## jcrews (Jun 8, 2021)

Q4 is good. Q3 is not.
Measure
Q3-C: -0.00
Q2-C (same as Q3-B): 8.9 volts
Q2-B -0.00

Is my 2n5087 DOA?


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## Chuck D. Bones (Jun 8, 2021)

Check your solder joints around Q2 and R5 - R8.  You have a short or a bad solder joint somewhere.  
Do the pots under the board have Jimmy Hats™?


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## Chuck D. Bones (Jun 8, 2021)

I think your transistors are ok.  Q2-B is zero volts.  Either Q2-B is shorted to gnd or R5 is open.


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## jcrews (Jun 8, 2021)

I will check all of that right now.  Man, you know this circuit real well, Thanks for all this quick help.  I surely appreciate it.


p.s. I always wrap it up if it's under the board


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## jcrews (Jun 8, 2021)

I'm about to unbolt it all again.  Here's a shot just to make sure your eyes see something mine don't.  I went over them with the meter up top and they all read right.


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## jcrews (Jun 8, 2021)

oh daing.  I just noticed the pots are switched.  Jesus.  I feel ashamed.  That ain't my only issue but I'll fix that too.  What voltage should I be seeing in q2 b?


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## Chuck D. Bones (Jun 8, 2021)

That won't cause this problem.  Did you measure the resistance of R6 in-circuit?



jcrews said:


> p.s. I always wrap it up if it's under the board


Wrap it with what?


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## jcrews (Jun 8, 2021)

I have it all out now so i need to solder the DC jack back in but I'll give you readings on R6 in an edit.  yeah i didn't figure the 100k and 50 switch caused this, but while i have it all out :-/  might as well.  I checked all my joints and i did find a leg off of Q3 i didn't trim short enough bend over and BARELY touching a leg from Q2.  Gonna clean all that up, swap boost and octave pots and try again.


R6 was 4.7k instead of 47k.  These eyes are trash

I promise im not usually this bad at this


edit:  i used standard pot dust cap covers on the middle three pots under the board


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## Chuck D. Bones (Jun 8, 2021)

BINGO.



jcrews said:


> Man, you know this circuit real well



We all should; it's the #1 board in the Troubleshooting forum.  Not all that hard to build, but it seems to attract noobs.  I'm not calling you a noob. 



jcrews said:


> What voltage should I be seeing in q2 b?



Approx 800mV.


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## jcrews (Jun 8, 2021)

Chuck D. Bones said:


> BINGO.
> 
> 
> 
> ...


Honestly..... I feel like a noob right now.  And I've got a nearly a hundred builds done.  Sometimes, you just make a bunch of dumb mistakes at once.

It's funny.... I've built some wild stuff with a million parts in tighter layouts, and this basic rat thing is giving me fits.....

Thanks again.


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## jcrews (May 4, 2021)

I dug thorugh some older threads but most are for the older board.  I used 1N34A diodes across the board in D1 D2 and D8 and D9.

It seems like I have the same issue. (no octave effect and turning up the octave knob cuts volume)

I just didn't see where we landed because I'm not using old school russian stuff.  I grabbed what was sold as GE 1N34A, but they look just like my silicon diodes.  Pic attached.

My first guess is to swap those around.  I'm assuming if they are marked backwards from what the circuit calls for, it wouldn't matter in the clippin section because all that matters is they be installed in opposite directions?

I'm going to try that first and report back.  If there's any other reason for the the whole "octave knob kills the output" issue everyone seems to have.... I'm all ears 

Thanks,

p.s. everything else works and sounds flawless.  Love the rat and the boost.  Really wanna hear the octave as that's the only "new" thing for me on this one.


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## jcrews (Jun 8, 2021)

Final update:

It sings now.  That octave is cool.  It's more than an octave.  It's nasty.  

So I 
a.) messed up the boost and octave pots (and boy are those ZERO fun to remove)
b.) misread my bands and put a 4.7k resistor in a 47k spot (r6 to be specific)


I am the noobest of noobs again 

Thanks to all.  Now i can finally get this one out of the "broken" pile.  Down to just one left


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## Chuck D. Bones (Jun 8, 2021)

Which diodes did you end up using?


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## jcrews (Jun 8, 2021)

The leaky russians (de9's i believe)    I know I know......  the bat 41's sounded fine.  A little more defined actually..... But i spent like 15 bucks on ten of the damn things, so after I fixed my resistor issue i popped em back in to see if they were ever the problem...... they weren't, and they have a rattier charecter than the bat's.  I wish i had socketed them the first round.  I have never before pulled more things out of a finished pedal than this one (4 diodes, 2 pots and a resistor, 2 ribbon cables).

Since they are socketed I'll keep playing around with it.  With my luck the cheapies i had in in first (non socketed) will probably sound the best.  It's a fitting punishment honestly.


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## Chuck D. Bones (Jun 8, 2021)

Save the D9x's for something that will make good use of them.  Anything with a hard clipper is a candidate.  I put 3 in a Chrystal drive in place of the Schottkys and they sounded good (check my Build Report). They'll also work well in a Klon or a Tone Machine.


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## fig (Jun 8, 2021)

Chuck D. Bones said:


> Save the D9x's for something that will make good use of them.  Anything with a hard clipper is a candidate.  I put 3 in a Chrystal drive in place of the Schottkys and they sounded good (check my Build Report). They'll also work well in a Klon or a Tone Machine.


In your opinion, what would be a solid auditioning circuit for clipping diodes (side-by-side audible & scope)?


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## jcrews (Jun 8, 2021)

sounds good.  I'll hang on to em.


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## Chuck D. Bones (Jun 8, 2021)

fig said:


> In your opinion, what would be a solid auditioning circuit for clipping diodes (side-by-side audible & scope)?


If I'm considering Germanium, first thing I do is analyze whether the circuit will tolerate the high leakage.  If the answer is "no," then it's down to silicon or LEDs.  I use a purely subjective approach.  I build a breadboard, play guitar thru it, try different diodes, usually with a toggle switch, and see if I have a preference. I get recommendations from folks here and I get ideas from other pedal designs.  It's all very ad-hoc.

A while back, I  tried Ge diodes in a BMP, with poor results.  The gain was very low.  That's because Ge diodes behave like they have a resistor in parallel.  They never really turn all the way off.  The more leakage, the lower the parallel resistor.  In low-impedance circuits, like hard clippers, that's usually ok, but in a high-impedance circuit I might just as well install a 10K resistor where the diodes would go. 

Recently, I started testing Ge diodes in a single-stage of the BMP circuit.  The clipping diodes are in the feedback loop, in parallel with a 470K resistor.  I measure the gain with the diodes out of the circuit, then measure the gain with the diodes in-circuit.  I keep the signal level low enough so that the diodes do not distort the signal.  What I'm measuring is the change in gain caused by the diode leakage.  From that I can calculate the effective leakage resistance of the diodes.

I also tried a similar circuit, using an opamp instead of a transistor, with diodes in the feedback loop.  The results were similar.  None of the Germanium diodes I have are suitable for use in a BMP because their leakage resistance is significantly lower that the 470K resistor in the feedback loop.

Once I'm satisfied that I have collected meaningful diode leakage data, I'll share it here.


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## fig (Jun 8, 2021)

Chuck D. Bones said:


> Once I'm satisfied that I have collected meaningful diode leakage data, I'll share it here.


Fantastic!


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## mnemonic (Jun 9, 2021)

New germanium diode pedal name - the leaky Russian


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