Shika fuzz farting

[matchandkerosene]

I built a Shika fuzz and it functions fine, but it’s farting out like a gated fuzz. Slamming another drive pedal seems to do the trick to get some useable sounds out of it, but curious if anyone has any recos to change the bias or get it to sound less gated. Using four 2n3904s for the transistors if this makes a difference.

 

[jesuscrisp]

Sounds like you should take check your part values and maybe post pictures of the build, both sides of the PCB.
Without seeing it, we may as well assume it's due to the upcoming full moon.

 

[matchandkerosene]

Sounds like you should take check your part values and maybe post pictures of the build, both sides of the PCB.
Without seeing it, we may as well assume it's due to the upcoming full moon.

Thanks and yeah good call- I just ran through everything. It’s worth mentioning I tried socketing some other 2n3904s in there to see if they were the culprit but didn’t have any luck. The tone knob makes an audible scratchy noise when turning on further inspection- but less “dusty” sounding than trimming a bias knob. It does seem to be quieter when playing and harder attacks and lower notes open it up. I posted some photos of the pcb front and back.

 

[chris.knudson]

First thing to check is your solder joints -- reflowing them never hurts. Farty sounds can be caused by lose connections, such as socketed transistors. Also bad transistors can be the culprit -- how confident are you that you have good transistors (there are a lot of bad transistors on the internet)?

 

[matchandkerosene]

First thing to check is your solder joints -- reflowing them never hurts. Farty sounds can be caused by lose connections, such as socketed transistors. Also bad transistors can be the culprit -- how confident are you that you have good transistors (there are a lot of bad transistors on the internet)?

Thanks for the tips- I’m definitely seeing a couple in there that look questionable. My soldering skills haven’t caught up with my enthusiasm yet lol. I suspect that center tone pot may have a cold solder joint. I believe the transistors were from Stompbox or Tayda. I believe I have some NOS transistors from Smallbear I can swap in to check those. I typically socket all ICs and transistors. Is it good practice to socket diodes too?

 

[chris.knudson]

Thanks for the tips- I’m definitely seeing a couple in there that look questionable. My soldering skills haven’t caught up with my enthusiasm yet lol. I suspect that center tone pot may have a cold solder joint. I believe the transistors were from Stompbox or Tayda. I believe I have some NOS transistors from Smallbear I can swap in to check those. I typically socket all ICs and transistors. Is it good practice to socket diodes too?

I don't usually socket diodes unless I want to experiment. I sometimes I socket transistors -- mostly because I've had a few bad ones, and unless I know they are good, socketing them isn't a bad idea. However, I always socket ICs if I can. There are a lot of fake ICs on the market, and sometimes you just get a bad one. It's so much easier to swap one out when it's socketed that having to desolder a component with 8 or more legs.

EDIT: StompBox, Smallbear, and Tayda should be good sources for transistors -- Amazon and Ebay aren't. Having said that, I've bought lots of good parts from Amazon, and I've heard stories of bad parts from Tayda (never been my personal experience), but anymore, I almost exclusively buy transistors from Mouser.

 

[matchandkerosene]

I don't usually socket diodes unless I want to experiment. I sometimes socket transistors -- mostly because I've had a few bad ones, and unless I know they are good, socketing them isn't a bad idea. However, I always socket ICs if I can. There are a lot of fake ICs on the market, and sometimes you just get a bad one. It's so much easier to swap one out when it's socketed that having to desolder a component with 8 or more legs.

Thanks Chris- yeah I checked the diodes and they appear to be ok and unbroken. I like the idea of socketing to hear the difference in different clipping diodes at some point. I just swapped all the transistors for some NOS ones I had and there is a slight difference in how they break up but overall no big change. I also took the time to reflow everything and check for movement- everything seems to be ok. Same results overall. I’m very diligent about checking values, but it’s possible I messed something up in the build process. Thanks for the suggestions

 

[chris.knudson]

From what I can tell, your solder joints look pretty good. Have you checked your JST-HX connectors. I'm a firm believer in those, but it's a manual connection that can cause problems.

 

[jesuscrisp]

Please post pictures of your build.

 

[matchandkerosene]

From what I can tell, your solder joints look pretty good. Have you checked your JST-HX connectors. I'm a firm believer in those, but it's a manual connection that can cause problems.

Checking into these tonight and will report back

 

[matchandkerosene]

Please post pictures of your build.

Photos were added to this (check post 1)

 

[chris.knudson]

Out of curiosity, did you reflow all of your solder joints? Looking at the top of the board, I see a few components that could be suspect. As a general rule of thumb, I like to see a little solder peeking through to the pad on the parts side of the board -- that almost guarantees that you don't have a cold solder joint.

 

[matchandkerosene]

I did go over everything and reflowed every joint. I was having a few issues getting good joints on caps and transistors mostly (solder repelling from pads). I cleaned out my brass Brillo thing and that has helped get some cleaner welds. Good tip on the pads and seeing a bit flow through too- I’m going to strive for this moving forward. Thanks for all the suggestions on this. In all the testing on this, I did find it to be wild after a reverb - it sounds very weak on its own, but a verb can prevent it from clamping down/gating and makes for a wildly gnarly texture I haven’t heard in a fuzz before. I still need to mess with the jst cables though to see if there are good connections there

 

[chris.knudson]

it sounds very weak on its own,

Let's get this thing sounding good on its own before worrying about how it sounds stacked with other pedals -- that's only going to add to the complexity of your troubleshooting.

 

[chris.knudson]

solder repelling from pads

That can mean that either your tip or the board are dirty -- tinning the tip can help or adding flux to the joint can help. It can also be a sign that your iron isn't getting hot enough.