Nein Fuzz 3rd Attempt/Failure

[Depattern]

this is probably a lost cause since im not skilled enough to properly troubleshoot. I have a multimeter but aside from basic voltage and continuity testing, i dont really know what im doing but i wanted to give it a shot after buying the pcb and jfets 3 separate times.

i thought i accounted for the dumb obvious mistakes in my first two builds (soldering the wrong component or pad, then severely botching the desoldering - im really bad at desoldering), and i felt like i did everything according to the instructions i had here. im 95% sure i didnt use any incorrect components like 470k vs 470r, and r2 is 47k. everything is oriented properly. q2 is only soldered like that because i was trying to get ai to help me and it wanted to me swap that jfet for another one due to the weird drain voltages:


but i think the orientation is correct (d,s,g from left to right when facing the top of the pcb). and the pins are soldered on the top and bottom. I know my soldering is shotty but the continuity tests ive done dont show any obvious issues


this is what i have so far:

• Q1 D: 8.06V
• Q2 D: 8.93V
• Q3 D: 1.248V
• Q4 collector: 3.9V
• Supply: 9.41V
• All carrier orientations verified (potentially)
• All resistors measured correctly (mostly)

powers on, led comes on with the switch but no audio when engaged. i get my clean guitar signal when switch is bypassed. sometimes i hear a tiny bit of scratchiness when turning the vol in pot (much moreso in my last build attempt), but really almost completely silent. one thing im kind of unsure of is the in/out jack soldering, which should be the most basic aspect of a build like this, but i guess that since im getting the clean bypassed signal its ok? i dont even know if thats true or helpful. i was thinking maybe its something simple like the ground points arent all connected, or the jfets arent making proper contact, but i've had the same issue when i soldered the smd jfets (non-pre-soldered) directly to the pcb pretty successfully.

I don't know if this is enough info for direct troubleshooting but im wondering if anything glaring sticks out, maybe even the poor soldering? although i have reflowed almost every single point that was even slightly dull but there are some bigger blobs remaining which ive attempted to re-do a few times. the jacks and power connections especially are bad due to the twisted awg wire, but those dont seem to be the issue as far as i can tell(?)

i used film caps for the first 2, then i bought a bulk box film cap pack for this one. i had some others on order from stompbox parts but they didnt arrive in time for this one. thats what the yellow 100n (104 100v) and 10n (103 100v) are

maybe someone as unskilled shouldn't be attempting this but i would really love to give this pedal a shot and i feel that it would be so much more satisfying that just buying another pre-built fuzz, even though i may unfortunately end up with no choice. it seems like a really rewarding pedal to build: the kind of overdriven tones, the unruly gnarly timbres, the chaotic biasing.

so really, any general troubleshooting or any ideas at all that maybe you would try yourself if you werent sure why a pedal build isnt working would be very helpful. claude ai usually does not steer me wrong but its been sending me down some mind numbing rabbit holes that arent helping with these builds at all



kind of a sentimental thing, as i had the genius idea of dedicating it to my dog who passed recently. so feels extra depressing to leave it broken

 

[Depattern]

when something isn't working the brainless first thing you can try, esp on a smaller circuit like this is just reflow suspect looking solder joints.

i think my problem is that since i was/am so bad at desoldering, if i attempt to reflow a blob, im just swishing around excess solder. but since starting this thread and using flux, i've gotten better at cleaning up huge blobs at least. so i will retry that

i still cant actually pull out an old component and clear the hole without completely ruining the trace/pad or giving up. im going to try the braid that was suggested upthread next time

but apart from that, im not really sure what to even attempt next. so i ordered another pcb and im going to use all of these tips in my next attempt. i havent given up one this one, im still trying. im just kind of at a loss for what to do from here. im getting even less audible contact points with my audio probe than i was getting before, but it still stops around r13 or slightly before that as far as i can tell from the schematic (which im not very adept at interpreting exactly)

on the topic of solder tips, tried using the knife tip (closest thing i currently have to a chisel) and it is not working out very well. i had much better luck with laying a bent chisel tip across the pad and the leg of the component for heating before bringing in the solder. but i dont have much to solder at the moment, so i'm going to give it a little more of a chance before abandoning that idea

 

[LukeFRC]

i still cant actually pull out an old component and clear the hole without completely ruining the trace/pad or giving up.

I'm guessing we are talking at cross purposes here, but just for clarity reflowing the solder doesn't involve removing parts - just heating it adequately to get a good solder joint

 

[LukeFRC]

im just kind of at a loss for what to do from here. im getting even less audible contact points with my audio probe than i was getting before, but it still stops around r13 or slightly before that as far as i can tell from the schematic (which im not very adept at interpreting exactly)

My debugging list...
1 check for obvious, volumes up, plugged in right socket, power in,
2 check the less obvious, have I got parts muddled?
3 reflow things. I don't have to think about it, just make sure the joints are better...
4 audio trace.


super simplified - red line is signal. VCC is power ground is ground.Obv turn up input, fuzz and vol...
Go through... signal at C2, R2, Q1 R7 C5 etc fiddle with the bias...

 

[Depattern]

I'm guessing we are talking at cross purposes here, but just for clarity reflowing the solder doesn't involve removing parts - just heating it adequately to get a good solder joint

yes i understand, i was addressing a few different things there. sorry for the confusion

i appreciate your advice and will do that.

EDIT: actually, i remember now; i was saying that i do have a decent amount of big blobs on there, which makes it difficult to reflow without using some desolder wick. but i think i have that process down. so i will be more efficient at reflowing in general, even when i do encounter those big globs of solder that are tough to reflow (my extrapolation on my issues with desoldering is likely what caused that confusion)

 

[Depattern]

got it working!

not sure if the bias knob is working 100% but it makes a significant enough difference that it seems functional. everything else is working. if i understand correctly, the fuzz is more of a lo-pass filter. if thats true, then every other knob is working fine as well

i reflowed everything, but the final fix was jumping from q3 drain to the right leg (facing the top of the pcb)

I couldn't have done it without everyone's help here and i can't thank you all enough. Im very glad i decided to post here, I'm currently writing down every piece of advice i got in my notes. i still might try to build a cleaner version as that jumper situation, and the replacement c6 box film 100nf cap that i was only able to kind of solder to the top of the pads on the board, are very precariously positioned in there. but i've learned so much here that i'm in a much better position to rebuild than i was before asking this forum for help

*Thanks again everybody