Parentheses mini fuzz only half working

JulienD

New member
Hi everyone,

I've contemplated building pedals for a long time, but took the plunge only a few weeks ago.
My first two (simple) builds went smoothly, but I ran into my first non-working build yesterday with a Parentheses Mini Fuzz, that is in fact half-working.

The bypassed signal is normal, and the boost side works perfectly, but the dist side doesn't.
I only get a very feeble amount of signal bleeding through a lot of white noise with all pots maxxed out.
I therfore assume that the issue doesn't reside in the power supply or jack in & out wiring, but most likely in the pcb, footswitch or pots wiring.

A few observations of interest:
- I don't have an audio probe (and won't have the parts to build one for at least another week or so), but I have a decent DMM.
- Offboard wiring and dpdt lug solder joints are ok, as evidenced by continuity tests with the DMM.
- The signal reaches at least the first components, but I can't test caps, diodes or transistors with a DMM.
- The IC is installed the right way, and so are the transistors (although I have no way to make sure they are spec-compliant).
- I've tried to switch them around (one by one, obviously), just to make sure the right orientation was specified on the PCB, to no success. It only makes a difference for Q5 (the last transistor before the volume pot, so post-IC and post-clipping); the white noise that I had with all pots maxxed out is now gone, but the small amount of guitar signal that was bleeding through is still audible, which leads me to believe that it comes from somewhere else than the intended signal path.
- Interestingly, the signal must reach at least as far as LED D6, located in one of the two clipping branches (and therefore post-IC), since it ligths up when I hit the strings.

So my questions for you guys are:
1) does the description of the issue and/or picture of my build ring a bell for some of you ?
2) how would you proceed from there?

Thanks a lot in advance!
 

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put the power to the pedal, use the voltage measurement on the multimeter. One probe to the central leg and the other probe to the side ones. You should have a non-zero value. Something like 8.5 and 0.25 if I remember correctly.
 
put the power to the pedal, use the voltage measurement on the multimeter. One probe to the central leg and the other probe to the side ones. You should have a non-zero value. Something like 8.5 and 0.25 if I remember correctly.
Great! Do I need to have some guitar signal going through the circuit, or is the power supply enough?
 
Here are the voltages I've measured on the IC pins, numbered as in the schematic attached.
1 : 9.1V
2: 4.6V
3: 4.2V
4: 0V
5: 0V
6: 4.6V
7: 9.1V
8: 9.1V

I can't help but notice some differences between your measurements and mine; did you use the same pin order?
Anyway, the symptoms you describe in your post are exactly the same as mine.

I've swapped the boost side LED power supply cables that were inverted on my build (what an idiot), tried to re-flow the IC socket pins, made sure that the LED leads were not touching anything, and checked that all pots have good continuity.
None of that worked.

I could order replacement Jfets and ICs, but considering the current delivery lead times, I guess all I have left to do is wait for my next order to show up in the mail (hopefully in the coming week) and build an audio probe.
Have you tried that?
 

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nope.. I'm also not an expert on these measurements.. I was hoping that someone that has a working version could compare these..?

I usually order components from european based ebay sellers and that leads to fast deliveries.
 
Yeah, that'd be helpful. Who are your reference supppliers, usually?
I haven't had to order single components yet (as opposed to ordering them as kits), but I may have too in the near future...
 
not sure if I can advertise here.. Just log in to ebay.fr or .co.uk and select sellers in europe. there are a couple in germany and GB that are fast shippers.

I hope someone from this forum could verify these measurements.. or provide some help.
 
Hi again everyone,

I received new components today, and was able to build an audio probe.
The results are pretty clear: the signal doesn't get past Q1. I have a crystal clear sound on my probe until leg 3 (and I do mean leg, not solder side of the socket), and nothing on leg 1 (which is normal, as it's the power supply) but nothing on leg 2 either (which isn't normal, as it's supposed to be the output).
I've double checked all components located directly after Q1: leg 2 of R4, and both sides of C3 and C10. Zero audible signal, regardless of the octave pot setting.
Finally I've tried swapping around the two PF5102s in the circuit (the other being Q5), which makes zero difference at all.
I want to jump to the conclusion that both of the PF5102s I got in the kit are fake (statistically, one non-working part out of several identical ones should be considered faulty, two out of two means fake).
Do you agree, or am I missing something?
 
I want to jump to the conclusion that both of the PF5102s I got in the kit are fake (statistically, one non-working part out of several identical ones should be considered faulty, two out of two means fake).
Do you agree, or am I missing something?

I can't find the thread, but I think someone else in the recent past came to this same conclusion.

Shoot Klaus at Musikding an email, I'll do the same. I doubt he's aware that there is an issue, I certainly don't think he's intentionally selling fakes (if that is the case).
 
I doubt he's aware that there is an issue, I certainly don't think he's intentionally selling fakes (if that is the case).
Oh I'm certainly not implying he is, but if they are fake indeed, it's best that he knows it as soon as possible, so he can fix the issue with the kits he's shipping for the short term and with his supplier for the long term.
 
Hi,

Just to add myself to the crowd -I just finished the same kit from Musikding as OP-, things are not working at all, but I can confirm that I have a valid signal path from input to output when jumping G & S on both 5102s (Q1 &Q5). If I'm not mistaken, that would support the hypothesis of duds/non-working JFETs.
 
Hi,

Just to add myself to the crowd -I just finished the same kit from Musikding as OP-, things are not working at all, but I can confirm that I have a valid signal path from input to output when jumping G & S on both 5102s (Q1 &Q5). If I'm not mistaken, that would support the hypothesis of duds/non-working JFETs.
I'm starting to sense a pattern here. I've written to Musikding, let's see what they answer.
 
I can't find the thread, but I think someone else in the recent past came to this same conclusion.

Shoot Klaus at Musikding an email, I'll do the same. I doubt he's aware that there is an issue, I certainly don't think he's intentionally selling fakes (if that is the case).
Guys, stop everything, I found the problem: it's the pinout on (our?) PF5102s that's not compatible with the way the PCBis laid out.
I reversed pins 2 and 3 (source and gate, is it?) and it worked right away.
I'll order some 5458s for the long term (as Stefanos suggested), and encourage you to do so to, but if you want to get your builds working until they get there, you know what to do!

Thanks a lot to the community for the appreciated help!
 
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