Parentheses Boost Problems

[A2K]

Well, add me to the list of people having issues with this build. I've had a number of problems (dead led's, enclosure mis-labeling, broken cables, BS170 legs breaking inside of its socket, etc) but my main problem is the boost.

When I first tested the pedal it all worked. Even the boost kind of worked. The problem was when I would engage the boost, the signal would go completely silent for a few seconds before fading in and seemingly work fine. Until I disengaged the boost, then the signal would go silent for a few seconds again before fading back in and coming back.

So, I tried some basic troubleshooting like reflowing solder, verifying resistor values, swapping BS170's, etc. This eventually lead to many of the other issues I mentioned earlier (broken transistor legs, broken cables, etc.). I then had to do a bunch of desoldering and resoldering. Fired up the pedal again and....same momentary signal loss issue but now the boost volume is extremely low (can barely hear any signal with the boost volume maxed).

Pictures:

20210724-140822 hosted at ImgBB

Image 20210724-140822 hosted in ImgBB

ibb.co

20210724-140939 hosted at ImgBB

Image 20210724-140939 hosted in ImgBB

ibb.co

20210724-141305 hosted at ImgBB

Image 20210724-141305 hosted in ImgBB

ibb.co

20210724-141334 hosted at ImgBB

Image 20210724-141334 hosted in ImgBB

ibb.co

Any idea what the problem might be?

 

[Feral Feline]

The circuit is cursed.

 

[Feral Feline]

Your diodes are all backwards. Line up diodes' stripey sides with stripey sides of silk screen.

Won't matter for clipping to ground, but for other things it could make a difference.

 

[fig]

Did you just say "stripey"?

 

[A2K]

Your diodes are all backwards. Line up diodes' stripey sides with stripey sides of silk screen.

If you're referring to the D9K diodes, the double white band is the anode on those.

The 1N4148s are correct too, although the angle of the photo does kind of make it look like those are backwards.

 

[Feral Feline]

Did you just say "stripey"?

YA DURNED TOOTIN' I DID!




I suspected some Rusky backwards stripies might be involved. Y'all posted while I was editing my thoughts... about clipping orientation not mattering here, and post editedededed.

PedalPCB Forum is an orientation-safe zone, no judgements here. Why, some of my best stripies are reverse oriented.

Somebody with a keener eye in front of some better grey matter will hopefully mosey on in...

 

[fig]

Do you have an audio probe, or can you fashion one? It may expedite your solution, barring someone spotting a gremlin, which would be great!

btw, I'm afraid I don't meet @Feral Feline 's above description. lotsa grey, but on da outside..not da inside.

 

[A2K]

Do you have an audio probe, or can you fashion one? It may expedite your solution, barring someone spotting a gremlin, which would be great!

I don't have an audio probe. From a quick look online, it doesn’t look that hard to make/use...

 

[fig]

If you're building several pedals, they are a cheap lifesaver, and they offer an educational bonus, by way of learning signal paths, and ID'ing different stages, etc (well, at least it has been for me).

 

[A2K]

If you're building several pedals, they are a cheap lifesaver, and they offer an educational bonus, by way of learning signal paths, and ID'ing different stages, etc (well, at least it has been for me).

I built an audio probe and if I'm using it correctly (maybe a big if) it seems like the issue is at the BS170. If I probe at the 1u cap before it, the signal sounds okay. Once I probe at the BS170 the signal volume goes way down. I'm assuming the volume should either increase or stay at unity after it passes through the BS170?

 

[ddavis20341]

Finally just managed to debug mine. It was actually a board issue - there was no connection between the input and R28 (unclear whether that was user error or it came that way, but it doesn't look like I messed up any of the traces anywhere). As soon as I put an alligator clip from the input pad to R28, the boost side worked perfectly.

As fig mentioned, audio probes are incredibly useful in debugging - I never would have thought to try that had I not gone through it with an audio probe.

 

[A2K]

Well, I eventually had to decide between 2 options for this pedal. Throw it through my window, or hand it over to someone else.

I chose option 2 and gave it to a local pedal builder who also does repairs (shout out to stonegatefx!). He was able to get it working but apparently my pcb also had a board issue...he said the input cap in the boost circuit (C21) wasn't connected. He had to make a connection with a small lead from the cap to the mosfet.